Medical marijuana laws in 50 states: Investigating the relationship between state legalization of medical marijuana and marijuana use, abuse and dependence

Abstract
Background

Marijuana is the most frequently used illicit substance in the United States. Little is known of the role that macro-level factors, including community norms and laws related to substance use, play in determining marijuana use, abuse and dependence. We tested the relationship between state-level legalization of medical marijuana and marijuana use, abuse, and dependence.

Methods

We used the second wave of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), a national survey of adults aged 18+ (n = 34,653). Selected analyses were replicated using the National Survey on Drug Use and Health (NSDUH), a yearly survey of ~68,000 individuals aged 12+. We measured past-year cannabis use and DSM-IV abuse/dependence.

Results

In NESARC, residents of states with medical marijuana laws had higher odds of marijuana use (OR: 1.92; 95% CI: 1.49–2.47) and marijuana abuse/dependence (OR: 1.81; 95% CI: 1.22–2.67) than residents of states without such laws. Marijuana abuse/dependence was not more prevalent among marijuana users in these states (OR: 1.03; 95% CI: 0.67–1.60), suggesting that the higher risk for marijuana abuse/dependence in these states was accounted for by higher rates of use. In NSDUH, states that legalized medical marijuana also had higher rates of marijuana use.

Conclusions

States that legalized medical marijuana had higher rates of marijuana use. Future research needs to examine whether the association is causal, or is due to an underlying common cause, such as community norms supportive of the legalization of medical marijuana and of marijuana use.

Source: Drug and Alcohol Dependence Volume 120, Issues 1–3, 1 January 2012

About 100 members of the Somali community have demonstrated outside Downing Street to call on the government to ban a herbal high.

Khat, which is illegal in the US and many countries in Europe, has been chewed for centuries in east Africa and the Middle East. The campaigners said it caused medical problems and family breakdowns.

The Advisory Council for the Misuse of Drugs is currently reviewing the harms associated with khat.

Effects of chewing the leaves of the khat plant include euphoria and extreme talkativeness, but side effects can include dizziness, heart problems and anxiety.

Fears have been raised that the stimulant is contributing to mental health problems within the communities that use it. Richard Hamilton, Africa editor for the BBC World Service, attended the demonstration.He said research suggested that more than a third of the over 100,000 Somalis in the UK have admitted to consuming khat on a regular basis.

The demonstrators said that the drug caused mental illness, depression, cancer and death from liver failure. They added that the social impact of khat has kept men away from work and led to the disintegration of families and local communities. Abukar Awale, who organised the demonstration, is himself a former khat addict.

“The number of families who are breaking down due to khat is beyond your imagination,” he said. There is clear evidence of medical and social harm.

“I’d like to bring to your attention a report which came out in 2011, called ‘khat related deaths’ there are fourteen cases – all young men, all of them died of liver failure.

“They are not related. The one factor they all have in common is excessive khat use, which leads us to believe there is huge evidence of medical harm.”

A Home Office spokesman said: “The Advisory Council for the Misuse of Drugs (ACMD) is currently reviewing the harms associated with khat. The government is required to consult the ACMD and will not prejudge this advice. The home secretary will consider the advice fully when it has been received, which is likely to be later this year.”

Source: www.bbc.co.uk/news 1st Nov 2012

Thailand will employ a proactive strategy in tackling drugs, the secretary of the National Narcotic Prevention and Supression Commission, Pol General Pongsapat Pongcharoen, said.

The offensive will take place throughout the Kingdom, starting with 12 communities in Klong Toei slum, and will involve monitoring those who have been treated after they were found to have drug addiction, he said.

Pongsapat, who is also a deputy chief of the National Police, said in the weekly television programme “PM Yingluck meets the people” that over the past year many big-time drug dealers had been arrested. But he was still concerned about drug addiction and trafficking in communities in Bangkok and its surrounding provinces.

This, he said, had led to the designation of various communities in order to better tackle the problem and many youths have given tips to the authorities while some of those affected in communities were yet to receive proper care that should include post-addiction livelihood training.

Pongsapat cited Klong Toei slum as the most drug-prone, especially in areas called Lock 1-3 and Lock 4-5 over a 70-rai area and occupied by some 7,000 to 8,000 people.

Some 3,000 youths were thought to be at risk, said Pongsapat, and the authorities had surrounded the communities to “x-ray every inch over a 90-day period”, which began on October 1. That includes police patrols, installing CCTV cameras and officers at all the 18 entrance and exits. This, he said, had led to many arrests so far.

Another measure is to campaign in the community that those addicted are like sick people and since October 14, 106 people, including parents and youths, had voluntarily sought drug treatment. These people were being sent to various treatment centres and it would take from 45 to 120 days for the rehabilitation process to conclude.

The Education Ministry has also been asked to help look after children who have no access to education in the areas. Deputy Premier Chalerm Yoobamrung has been appointed as director of Palang Paendin (Power of the Land) Centre that seeks to win the “war on drugs”.

Throughout the country, 878 districts will deploy a strategy similar to what is being used in a Klong Toei slum, including crackdowns on drug transport and trafficking. Three areas in Bangkok will be particularly targeted along with nine provinces.

More than 400,000 people have been rehabilitated so far and the government is trying to introduce a one-stop service centre.

Meanwhile, Prime Minister Yingluck went to a Klong Toei slum yesterday to inaugurate the Baan Unjai Project (Reassuring Home Project), coinciding with the crackdown on drugs in the area.

Yesterday morning, two drug users were arrested in the area for possessing “ice”.

Dusit Poll, meanwhile, revealed that a majority of respondents supported Priephan Damapong as deputy premier to tackle the drugs issue.
Source: www.asiaone.com 21st Oct.2012

Study finds babies at higher risk for devastating birth defect, later learning disabilities

New high-potency marijuana and synthetic “weed” can interfere with early brain formation in developing fetuses, according to a new study, and many pregnant women may be unaware of the heightened risk. “2Harmful effects of psychoactive chemicals in marijuana now on the market can begin as early as two weeks after conception, the study found. This is particularly troubling as marijuana is the most widely used illicit drug among pregnant women, the researchers say.

The study was published online Aug. 13 in Drug Testing and Analysis.

“The emergence of bioengineered crops and novel, medicinal marijuana strains, means that marijuana is no longer what it used to be in the 1970s and early 1980s,” said study co-author Delphine Psychoyos, at the Center for Genetic and Environmental Medicine at Texas A&M University, in a journal news release.

“Some new, high-potency strains, including some medicinal marijuana blends, contain up to 20 times more THC, the psychoactive constituent of marijuana, than did ‘traditional’ marijuana'” from decades past, Psychoyos said. “Easy access to drugs via the Internet or dispensaries makes the problem worse” she added.

Exposure to latter-day versions of marijuana in early pregnancy is associated with anencephaly, a devastating birth defect in which infants are born without large parts of their brain or skull, the study found. The study also tied early prenatal use of these drugs to attention-deficit/hyperactivity disorder (ADHD), learning disabilities and memory problems in toddlers and 10-year- olds, as well as depression, aggression and anxiety in teens. To reach their conclusions, study authors reviewed current data on the effect of these chemicals during the earliest stages of development of the central nervous system in fetuses.

Many parenting and pregnancy websites and pro-marijuana advocacy groups base their views on marijuana on data collected prior to 1997, before the emergence of new and bioengineered marijuana strains, such as Spice products, the researchers said.

So-called synthetic marijuana or “fake weed” mixtures contain “synthetic cannabinoids” that are 500 to 600 times more potent than marijuana’s THC, according to the release. High-potency marijuana could also pose a risk to teens and young adults.

“Marijuana has regained its popularity from the 1970s, especially among teens and young people, and has established social and cultural status as the most popular drug of abuse,” Psychoyos said. “Yet, like pregnant women, these young users probably have no idea of the significant increase in potency over the past four decades.”

The researchers called on the U.S. government to revise policy on marijuana based on the development of synthetic cannabinoids.

SOURCE: Drug Testing and Analysis, news release, Aug. 13, 2012

Today’s headline was pretty bold: Smoking pot leads to double the risk of developing testicular cancer. Testicular cancer is on the rise, and experts have been trying for awhile to figure out why. Now, after comparing groups of young men who smoked and those who didn’t, there’s a possible answer. Those who smoked pot recreationally were twice as likely to develop testicular germ cell tumors, or nonseminomas, the most common kind in men under 35, says a study in Cancer. Nonseminomas are faster growing and harder to treat – a deadly combination – say researchers at the University of Southern California.

This study, though small, is actually the third study to link nonseminomas to pot use; the first two were also published in Cancer. The first word of the connection came out in 2009 from research out of the Fred Hutchinson Cancer Center in Seattle. The pot use researchers studied was described as “once a week or more”, and it’s important to note that many smokers toke up every day. No studies have contradicted the link, experts point out. It’s important to note that the risk of testicular cancer is relatively low, slightly more than 1 percent, so even when the risk is doubled, it’s still extremely small.

Pot Smoking May Lower IQ

Last week’s headline was at least as alarming as this week’s. Researchers followed a group of youngsters from age 13 to age 38, and found that the IQs of regular pot smokers fell up to 8 points during the 25-year period, compared with the IQs of those who didn’t smoke pot, which stayed the same. The study, published in the Proceedings of the National Academy of Sciences, also found an increase in memory and attention problems among those deemed marijuana-dependent.

Pot Smoking May Trigger Schizophrenia There should have been headlines, “Marijuana May Make You Psychotic” at least a couple times over the past few years, but somehow the studies documenting this issue haven’t gotten as much attention as you might expect. Maybe it’s because this link is much harder to prove, which it is. That’s because the association could work backward: Those who smoke pot could be self-medicating for symptoms of schizophrenia that hasn’t become full-blown yet.

However, there have been several studies, and they’ve controlled for a backwards causation pretty well. In a German study that followed a group of teenagers for ten years, those who smoked pot at least 5 times were more than twice as likely to develop schizophrenia. The biggest and probably best known study followed 45,000 young men in Sweden starting when they enlisted in the military. As I reported in a previous article, synthetic marijuana, also known as “Spice”, has also been linked to psychosis as well as to paranoia and violence. Fifteen years later, those who smoked pot at least once were more than twice as likely to develop schizophrenia. A third study followed young men whose family genetic history predisposed them to develop schizophrenia. In these kids, who are considered to have a one in ten chance of developing schizophrenia, pot use doubled that risk to one in five.

Pot Smoking Lowers Fertility and Causes Genetic Damage

The health risks of marijuana for women are much less well known, as of yet. But what is known is that pot smoking decreases fertility for both men and women, and appears to have the potential for genetic damage to future children. Though a complex mechanism, cannabinoids — the chemicals in cannabis — affect the production of sperm

and the ability of the sperm and egg to join together. The research on pot and testicular cancer has implicated the endocannabinoid system, which is the cellular network that reacts to cannabis, the active ingredient in pot. The endocannabinoid system also plays a central role in sperm production.

There’s also been considerable research on the issue of marijuana use causing genetic mutations that are then passed on to children. Of course most folks under 20 aren’t looking ahead to the health of their future offspring — or to the possibility of not being able to have said offspring — so this health issue is less influential with teens and young adults. But it’s something everyone should be paying more attention to.

Source: http://www.forbes.com/sites/melaniehaiken/2012/09/10

A new study from the University of Southern California (USC) has found a link between recreational marijuana use and an increased risk of developing subtypes of testicular cancer that tend to carry a somewhat worse prognosis. Published early online in Cancer, a peer-reviewed journal of the American Cancer Society, the findings suggest that the potential cancer-causing effects of marijuana on testicular cells should be considered not only in personal decisions regarding recreational drug use, but also when marijuana and its derivatives are used for therapeutic purposes in young male patients. Testicular cancer is the most common cancer diagnosed in young men ages 15 to 45 years. The malignancy is becoming more common, and researchers suspect this is due to increasing exposure to unrecognized environmental causes. To see if recreational drug use might play a role, Victoria Cortessis, MSPH, PhD, assistant professor of preventive medicine at the Keck School of Medicine of USC in Los Angeles, and her colleagues looked at the self-reported history of recreational drug use in 163 young men diagnosed with testicular cancer and compared it with that of 292 healthy men of the same age and race/ethnicity. The investigators found that men with a history of using marijuana were twice as likely to have subtypes of testicular cancer called non-seminoma and mixed germ cell tumors. These tumors usually occur in younger men and carry a somewhat worse prognosis than the seminoma subtype. The study’s findings confirm those from two previous reports in Cancer on a potential link between marijuana use and testicular cancer. “We do not know what marijuana triggers in the testis that may lead to carcinogenesis, although we speculate that it may be acting through the endocannabinoid system—the cellular network that responds to the active ingredient in marijuana—since this system has been shown to be important in the formation of sperm,” said Cortessis. The researchers also discovered that men with a history of using cocaine had a reduced risk of both subtypes of testicular cancer. This finding suggests that men with testicular cancer are not simply more willing to report a history of using recreational drugs. While it is unknown how cocaine may influence testicular cancer risk, the authors suspect that the drug may kill sperm-producing germ cells since it has this effect on experimental animals. “If this is correct, then ‘prevention’ would come at a high price,” Cortessis said. “Although germ cells cannot develop cancer if they are first destroyed, fertility would also be impaired. Since this is the first study in which an association between cocaine use and lower testis cancer risk is noted, additional epidemiological studies are needed to validate the results.” More information: “Population-based case-control study of recreational drug use and testis cancer risk confirms association between marijuana use and non-seminoma risk.” John Charles A. Lacson, Joshua D. Carroll, Ellenie Tuazon, Esteban J. Castelao, Leslie Bernstein, and Victoria K. Cortessis. Cancer; Published Online: September 10, 2012
Note: Professor Cortessis comment about ‘prevention would come at a high price’ refers to the fact that whilst cocaine might influence testicular cancer risk it would incur addiction and the health risks that come from such use.

Source: http://medicalxpress.com/news/2012-09-marijuana-testicular-cancer.10 Sept.2012

Oxytocin is best known for its role in creating social bonds, but it may also forge the chains of addiction. The “love hormone” oxytocin can relieve symptoms of withdrawal in people recovering from alcoholism, according to a small new study.

Research has long suggested that oxytocin— called the “love” or “hug” hormone for its role in social bonding— is a complicated chemical. It is released during orgasm and birth and other bonding moments between lovers or family members, but oxytocin may also help create the unhealthy ties that bind alcoholics and addicts to their drugs of choice.

Indeed, in rodents, oxytocin can successfully fight unpleasant alcohol and heroin withdrawal symptoms. And if given before the addiction even occurs, the hormone may even prevent the development of tolerance and symptoms of physical dependence.

The new study included 11 people with alcoholism severe enough to produce withdrawal symptoms, but not so severe that this withdrawal would produce potentially life-threatening seizures.

That was important, because during detox, people with alcoholism are typically given benzodiazepines. These are drugs like Valium (diazepam) or Ativan (lorazepam) and they relieve withdrawal symptoms, including seizures. People who suffer seizures must be given regular doses of the drugs; others can just take them as needed for comfort. The doses taken by those not at risk of seizures, consequently, provide a good measure of how bad the withdrawal is.

And oxytocin was found to help dramatically. Those given the hormone required nearly five times less lorazepam to get through detox, compared to those on placebo. They also had less anxiety.

“Our results are the first evidence that [oxytocin] may block alcohol withdrawal symptoms in humans,” the authors write. They say, however, that the results should be considered “very preliminary” because of the extremely small number of participants.

Oxytocin itself is not addictive: most people given a nasal spray containing the hormone cannot distinguish it from placebo, although about 1/3 of men get erections and people do become more trusting and cooperative in some settings. It does not automatically cause people to fall in love either, at least not in any of the research conducted so far.

So why might it be involved in addiction? It’s not yet clear but some research suggests that oxytocin essentially “wires” your lover or child to your reward system, so that it is activated and you feel good when the person is present— and not so good when he or she is not there or you fear the loss of the relationship. The oxytocin itself isn’t rewarding: it is simply connecting the reward with the memory of the person and the relationship. In the case of addiction, it could instead “wire” the system to the presence or absence of the drug. Increasing oxytocin levels, therefore, might cue the reward system to react the way it does in the presence of the drug, relieving withdrawal. The research was led by Cort Pederson of the University of North Carolina at Chapel Hill and published in Alcoholism: Clinical and Experimental Research.

Source: healthland.time.com 15th October 2012

Review of the application of positive psychology to substance use, addiction, and recovery research. (link to:http://psycnet.apa.org/?&fa=main.doiLanding&doi=10.1037/a0029897)

If unable to obtain a copy by clicking on title above you could try asking the author for a reprint (normally free of charge) by adapting this prepared e-mail or by writing to Dr Krentzman at amykrent@med.umich.edu.

The contemporary recovery movement in addictions and the positive psychology movement in the broader field of psychological health have recently grown in prominence but almost entirely in parallel streams, yet the overlaps and possible synergies between them suggest that an integration could be a step forward in recovery from addiction.

Summary

This review and conceptual analysis explores the overlaps and differences between (only briefly mentioned in this account) and research findings relating to two relatively new movements in psychology and addiction. Over the past decade, both fields independently recognised their work focused disproportionately on illness and pathology. Scholars in psychology called for the scientific study of human flourishing, which become the fast-growing subspecialty of positive psychology, while scholars in addictions research called for a new focus on recovery and sobriety, which became realised in the grassroots recovery movement.

Their similarities are in the emphasis on wellness rather than illness, and optimism that people can not only overcome pathology but develop more positive lives. However, they differ in important ways. The addiction recovery movement is a multifaceted grassroots effort led by people in recovery from substance use disorders, built on a recovery-oriented rather than pathology-oriented framework. Participants in the recovery movement work collectively to remove obstacles to treatment, support multiple paths to recovery, and make broader social systems more supportive of recovery lifestyles. The distinctive focus is primarily on macro-systemic change targeting policies, treatment systems, community resources, and social phenomena including stigma.

While the recovery movement has grass roots, positive psychology was sprouted in academic soil, but quickly spread to sections of the general population eager to improve their lives, lending it the character of a larger movement spreading beyond academia. Although positive psychology is concerned with positive organisations, its primary emphasis has been psychological change at the level of the individual. It recognises that there is more to mental health than the absence of mental illness – strengths, well-being, optimal functioning and flourishing. Flourishing individuals have been defined as “filled with emotional vitality … [and] functioning positively in the private and social realms of their lives”. Rather than seeking to overturn previous ‘psychologies’, positive psychology emphasises what it sees as some important but previously neglected perspectives.

Within this perspective, a positive intervention is defined as “an intervention, therapy, or activity primarily aimed at increasing positive feelings, positive behaviors, or positive cognitions, as opposed to ameliorating pathology or fixing negative thoughts or maladaptive behavior patterns”. A subset of these interventions called ‘positive activity interventions’ can be completed without professional help. Two widely tested examples which may have potential in substance use disorders are the gratitude intervention called Three Good Things (write down three things that went well each day and their causes every night for a week) and the optimism intervention, Best Future Self (write

down the realisation of all of your life dreams when in the future everything has gone as well as it possibly could).

Main findings

Recovery approaches

So far limited work on contemporary recovery approaches to addictions suggests that new recovery institutions are filling a gap left by traditional professional treatment and mutual aid groups, and that continuing care interventions may offer benefits beyond those provided by acute care.

Some of the strongest findings (because they derive from randomised trials) related to the Oxford House recovery homes where individuals in recovery live, share expenses, and provide mutual abstinence-specific social support and other forms of concrete and emotional assistance. Residents themselves manage the business of the household and there are no limits on stays. For the randomised trial researchers recruited 150 adults from inpatient units in Illinois who agreed to be randomly allocated to usual care (the control group) or to apply to Oxford Houses. Compared to the control group, over the two-year follow-up period fewer Oxford House assignees were using alcohol or drugs or charged for a recent offence and more were employed. By the end fewer than half as many (31% v. 65%) were using alcohol or drugs, a third as many were in prison (3% v. 9%), and average earnings were substantially higher. All these differences were reported as statistically significant. Additionally, at two years 27% more Oxford House assignees had their own accommodation and nine more mothers had regained or retained custody of their children.

Another set of findings from randomised trials support the recovery movement’s insistence that addiction should be treated as a chronic rather than acute disorder, implying long-lasting or open-ended support. Two trials have tested so-called ‘recovery management checkups’, quarterly meetings between counsellors and clients that take place consistently for two or three years – longer than traditional aftercare models – and treat each follow-up as an opportunity for intervention. After improvements were made, in the later trial checkup patients were more likely than controls to re-enter treatment if needed and received more treatment, attended more self-help meetings, achieved more days of abstinence, and lived in the community for shorter periods in a state where they needed, but did not receive, treatment. [Editor’s note: these and other studies have recently been reviewed, the results of which led an expert panel to argue that extended and regular monitoring of patient progress was the key component of continuing care and one with the greatest evidence of effectiveness.]

Positive psychology How well do positive psychology interventions work? Beyond the addictions, a meta-analysis of 51 randomised controlled studies of positive interventions amalgamated data from studies of healthy individuals and those suffering from depression. It found beneficial impacts in the form of moderate effect sizes for well-being and depression.

But a closer look at the research reveals that ‘it works’ would be too simple a verdict. In one body of work statistically significant differences were found when gratitude interventions were contrasted with ‘hassles’ conditions which ask participants to list things that irritate, annoy, or bother them, but not when they were compared to nothing intended to be an active intervention, except among groups more at risk than healthy populations. An emerging pattern suggests that those at a slight or great disadvantage, either because of illness, feeling bad, or being highly self-critical, seem to benefit more from a gratitude intervention than healthier individuals. In respect of substance use, just one study (conducted in the UK) has applied positive psychology, in this case during group therapy of ten 14–20-year-olds attending an alcohol and drug treatment service for young people, comparing their results to a control group of ten not offered this extra intervention until later. The eight-week intervention promoted positive emotions, savouring, gratitude, optimism, strengths, relaxation, meditation, goal-setting and change, relationships, nutrition, physical activity, resilience, and growth. Compared to the controls, it led to greater increases in happiness, optimism, and positive emotions, and a much greater but (given small samples and highly variable levels of drinking) not statistically significant remission in symptoms of alcohol dependence.

Though these are the only findings specifically testing effectiveness, engagement in anti-relapse mutual aid and variables related to relapse to dependent substance use have been found to be related to key constructs in positive psychology. For example, among 126 former problem substance users abstinent for at least six months, the construct of ‘hope’ was strongly and positively correlated with other positive psychology constructs and with relapse-related variables including having a sense of purpose in life, social support, self-efficacy and psychiatric symptoms. The same was generally not the case however for ‘spiritual transcendence’ and ‘flow’ – the experience of losing oneself in pleasing, enjoyable activity.

In another study of 164 AA members sober for at least a year, the intensity of affiliation to AA was significantly associated with optimism, gratitude, purpose in life, and spirituality. However, this sample were relatively well-off and well educated and highly involved with AA.

These findings suggest that hope is possibly important in sustaining recovery, and are in line with findings that spiritual/religious practices are a mechanism via which AA affiliation affects drinking.

The author’s conclusions

Despite tremendous growth in both positive psychology and the recovery culture, only the nine studies reviewed in this article have so far explicitly applied the discoveries of positive psychology to substance use, addiction treatment, and recovery, yet in other sectors these approaches have become prominent. The recovery movement has historically been an initiative for macro systemic change, while positive psychology has historically promoted micro interventions designed to create change at the level of the individual. Integrating the two can more comprehensively engage the spectrum of care necessary to adequately address addiction.

Source: Findings.org.uk 17th October 2012 Krentzman A.R. Psychology of Addictive Behaviors: 2012

Many people experiment with cannabis during their adolescence and early adulthood, and new research shows this is a particularly dangerous age because the brain is still developing. A recent study reported in the Oxford University Press found compelling evidence that brain reacts differently to cannabis exposure that commences during adolescence compared with adulthood.

The aim of the study was to examine the “white matter” pathways within the brain to see if they are changed through long-term heavy cannabis use. It was also hypothesized that the earlier someone started heavy and regular cannabis use the more severe the affect would be on these pathways in the brain.

White matter is the tissue through which messages pass between different areas of gray matter within the brain. Using a computer network as an analogy, the gray matter can be thought of as the actual computers themselves, whereas the white matter represents the network cables connecting the computers together. There are three different kinds of tracts, or bundles of axons which connect one part of the brain to another and to the spinal cord, within the white matter: projection tracts that extend vertically between higher and lower brain and spinal cord centers; commissural tracts cross from one cerebral hemisphere to the other through bridges called commissures; and association tracts that connect different regions within the same hemisphere of the brain.

To measure the effect of cannabis on the “white matter” pathways, the study looked at long term habitual users of cannabis with a minimum usage of twice a month for the past 3 years (although most recruited in the study had substantially greater use than this) and compared them with healthy non-users. In-depth brain imaging and brain connectivity mapping techniques were performed in each of the 59 cannabis users with longstanding histories of heavy use and the 33 healthy non-users who served as controls.

After examining the habitual heavy cannabis users, researchers found the axonal pathways were impaired in the right fimbria of the hippocampus, splenium of the corpus callosum and commissural fibers. It is also important to note that all of these areas that were impaired have an abundance of cannabinoid receptors.

The amount of damage to these pathways was also directly associated with the age at which regular cannabis use commenced. This resulted in long term users having greater instance of anxiety and depressive symptoms and lower Global Assessment of Functioning scores (a measurement of social, occupational and psychological functioning).

This association presents compelling evidence for white matter reacting differently to cannabis exposure commencing during adolescence compared with adulthood, most likely due to the high concentration of cannabinoid receptors contained within structures, such as the corpus callosum and fornix during adolescence.

These results suggest that long-term cannabis use is hazardous particularly to white matter in the developing brain of adolescents and young adults. Damage to these vital pathways during brain development may later lead to cognitive impairment and vulnerability to psychosis, depression and anxiety disorders, all of which are significant

public health concerns. White matter alterations have been associated with various functional and clinical outcomes in schizophrenia, including illness, symptomatic and cognitive measures.

Source: http://www.medscape.com/viewarticle/766633?src=journalnl 16th Oct 2012

Cigarettes and alcohol serve as gateway drugs, which people use before progressing to the use of marijuana and then to cocaine and other illicit substances; this progression is called the “gateway sequence” of drug use. An article in Science Translational Medicine by study author Denise Kandel, PhD, of the Mailman School of Public Health; and Amir Levine, MD; Eric Kandel, MD; and colleagues at Columbia University Medical Center provides the first molecular explanation for the gateway sequence. They show that nicotine causes specific changes in the brain that make it more vulnerable to cocaine addiction — a discovery made by using a novel mouse model.

Alternate orders of exposure to nicotine and cocaine were examined. The authors found that pre-treatment with nicotine greatly alters the response to cocaine in terms of addiction-related behavior and synaptic plasticity (changes in synaptic strength) in the striatum, a brain region critical for addiction-related rewards. On a molecular level, nicotine also primes the response to cocaine by inhibiting the activity of an enzyme?histone deacetylase?in the striatum. This inhibition enhances cocaine’s ability to activate a gene called FosB gene, which promotes addiction.

The relationship between nicotine and cocaine was found to be unidirectional: nicotine dramatically enhances the response to cocaine, but there is no effect of cocaine on the response to nicotine. Nicotine’s ability to inhibit histone deacetylase thus provides a molecular mechanism for the gateway sequence of drug use.

Nicotine enhances the effects of cocaine only when it is administered for several days prior to cocaine treatment and is given concurrently with cocaine. These findings stimulated a new analysis of human epidemiological data, which shows that the majority of cocaine users start using cocaine only after they have begun to smoke and while they are still active smokers. People who begin using cocaine after they’ve started smoking have an increased risk of cocaine dependency, compared with people who use cocaine first and then take up smoking.

“These studies raise interesting questions that can now be further explored further in animal models,” said Dr. Kandel, a professor of Sociomedical Sciences at the Mailman School. “Do alcohol and marijuana — the two other gateway drugs — prime the brain by the same mechanism as nicotine? Is there a single mechanism for all gateway sequences, or does each sequence utilize a distinct mechanism?”

The results also emphasize the need for developing effective public health prevention programs encompassing all nicotine products, especially those targeted toward young people. Effective interventions not only would prevent smoking and its negative health consequences but could also decrease the risk of progression to chronic use of illicit drugs.

Source: ScienceDaily (Nov. 2, 2011)

This paper comprises three decades of scientific study on the negative and potential positive effects of marijuana and human health.

JUST THE FACTS: Marijuana and Health

Marijuana is the subject of heated debate in our country. Despite one’s view on marijuana policy, it is critical to be well-versed in the science.

Marijuana is one of the most misunderstood drugs of our time. Sifting through the rhetoric about the drug can be difficult, but now we have a plethora of scientific studies from which to draw firm conclusions about the use of the drug and its public health implications.

Marijuana and The Brain

Marijuana use directly affects the brain, specifically the parts of the brain responsible for memory, learning, attention, and reaction time. These effects can last up to 28 days after abstinence from the drug.1

1 Hall W & Degenhard L (2009). Adverse health effects of non-medical cannabis use. Lancet, 374:1383-1391.

2 Giedd. J. N. (2004). Structural magnetic resonance imaging of the adolescent brain. Annals of

the New York Academy of Sciences, 1021, 77-85. And see 3 See, for example http://news.olemiss.edu/index.php?option=com_content&view=article&id=4545%3Acannabispotency051409&Itemid=10

Science confirms that the adolescent brain, particularly the part of the brain that regulates the planning complex cognitive behaviour, personality expression, decision making and social behaviour, is not fully developed until the early to mid-20s. Developing brains are especially susceptible to all of the negative effects of marijuana and other drug use.2

What makes marijuana harmful? Three simple letters: T-H-C

Marijuana contains about 500 components, most of which we know little about. The most prominent component is called THC. Scientists have found that THC is what produces the “high” users experience. In today’s street marijuana, which is usually smoked, producers have increased THC levels by more than four-fold3, and reduced the natural levels of other components that have actually been shown to reduce the high. Higher THC content can increase all of the usual negative effects of the

drug. 4, 5 In the U.S., for example, since 1990, more people have gone to the emergency room after using marijuana even though the overall numbers of marijuana users has remained relatively stable.6,7

4 Hall W & Degenhard L (2009). Adverse health effects of non-medical cannabis use. Lancet, 374:1383-1391.

5 NIDA, Research Report Series: Cannabis Abuse, 2010

6 Substance Abuse and Mental Health Services Administration, Center for Behavioral Health Statistics and Quality. (2011). Drug Abuse Warning Network, 2008: National Estimates of Drug-Related Emergency Department Visits. HHS Publication No. SMA 11-4618. Rockville, MD.

7 See for example Compton, W., Grant, B., Colliver, J., Glantz; M., Stinson, F. (2004). Prevalence of Cannabis Use Disorders in the United States: 1991-1992 and 2001-2002Journal of the American Medical Association.. 291:2114-2121. And Sabet, K. (2006). The (often unheard) case against cannabis leniency. In Pot Politics (Ed. M. Earleywine).Oxford University Press, pp. 325-355.

8 Hall W & Degenhard L (2009). Adverse health effects of non-medical cannabis use. Lancet, 374:1383-1391.

9 Tetrault, J.M., et al. Effects of cannabis smoking on pulmonary function and respiratory complications: a systematic review. Arch Intern Med 167, 221-228 (2007).

10 Hoffman, D.; Brunnemann, K.D.; Gori, G.B.; and Wynder, E.E.L. On the carcinogenicity of marijuana smoke. In: V.C. Runeckles, ed., Recent Advances in Phytochemistry. New York: Plenum, 1975.

11 See, for example: Moore TH, Zammit S, Lingford-Hughes A, et al. Cannabis use and risk of psychotic or affective mental health outcomes: A systematic review. Lancet 370(9584):319–328, 2007. Also Large, M., Sharma S, Compton M., Slade, T. & O., N. (2011). Cannabis use and earlier onset of psychosis: a systematic meta-analysis. Archives of General Psychiatry. 68. Also see Arseneault L, et al. (2002). Cannabis use in adolescence and risk for adult psychosis: longitudinal prospective study. British Medical Journal. 325, 1212-1213.

12 Hall W & Degenhard L (2009). Adverse health effects of non-medical cannabis use. Lancet, 374:1383-1391.

The main health harms of marijuana can be summarized as follows:

Heart: Marijuana use can cause an increase in the risk of a heart attack more than four-fold in the hour after use, and provokes chest pain in patients with heart disease. 8

Lungs: Research has shown marijuana smoke to contain carcinogens and to be an irritant to the lungs, resulting in greater prevalence of bronchitis, cough, and phlegm production.9 Marijuana smoke contains 50-70 percent more carcinogenic hydrocarbons than does tobacco smoke, as reported by the American Lung Association.10 Scientists have not found a definitive marijuana-lung cancer link.

Mental Health: Marijuana use has been shown to be significantly linked with mental illness, especially schizophrenia and psychosis, but also depression and anxiety.11

Pregnancy: Marijuana smoking during pregnancy has been shown to decrease birth weight, most likely due to the effects of carbon monoxide on the developing fetus.12

Marijuana and Addiction

An often heard phrase is that “marijuana is not addictive.” In fact, scientific research has found that 1 in 10 marijuana users will become addicted to the drug. And if one begins in adolescence, that

number rises to 1 in 6.13 Users who try to quit experience withdrawal symptoms that include irritability, anxiety, insomnia, appetite disturbance, and depression. 4, 5 Additionally, data from the National Institute on Drug Abuse found that in 1993 marijuana comprised approximately 8% of all treatment admissions, but by 2009 that number had increased to 18%.14 For those under 18, marijuana related treatment admissions increased by 188 percent from 1992 to 2006 while other drugs remained steady.15

13 Wagner, F.A. & Anthony, J.C. From first drug use to drug dependence; developmental periods of risk for dependence upon cannabis, cocaine, and alcohol. Neuropsychopharmacology 26, 479-488 (2002).

14 Substance Abuse and Mental Health Services Administration. (2009). Office of Applied Studies. Treatment Episode Data Set (TEDS): 2009 Discharges from Substance Abuse Treatment Services, DASIS.

15 Substance Abuse and Mental Health Services Administration. (2009). Office of Applied Studies. Treatment Episode Data Set (TEDS): 2009 Discharges from Substance Abuse Treatment Services, DASIS.

Also see Non-medical cannabis: Rite of passage or Russian roulette? (2011).Center on Addiction and Substance Abuse, Columbia University.

16 Room, R., Fischer, B., Hall, W., Lenton, S. and Reuter, P. (2010). Cannabis Policy: Moving Beyond Stalemate, Oxford, UK: Oxford University Press.

17 MacCoun, R. J. (2011), What can we learn from the Dutch cannabis coffee shop system?. Addiction, 106: 1899–1910.

18 Drummer, O.H., Gerostamoulos, J., Batziris, H., Chu, M., Caplehorn, J.R., Robertson, M.D., Swann, P. (2003). The incidence of drugs in drivers killed in Australian road traffic crashes. Forensic Science International, 134(2-3), 154-162.

19 European Monitoring Centre for Drugs and Drug Addiction. (2003) Drugs and driving: ELDD comparative study. Lisbon, Portugal: Author. Retrieved March 29, 2011 from http://www.emcdda.europa.eu/attachements.cfm/att_5738_EN_Quantities.pdf

20 Mørland J. (2000) Driving under the influence of non-alcoholic drugs, Forensic Science Review, 12, 80-105.

21 ROSITA Roadside Testing Assessment: www.rosita.org

22 DRUID: www.druid-project.eu

23 Verstraete, A.G. & Raes, E. (Eds.). (2006). Rosita-2 Project Final Report. Ghent Belgium: Ghent University.

24 M. Asbridge, J. A. Hayden, J. L. Cartwright. Acute cannabis consumption and motor vehicle collision risk: systematic review of observational studies and meta-analysis. BMJ, 2012; 344 (feb09 2): e536 DOI:10.1136/bmj.e536

Data in the United States is corroborated with data from other countries. In the European Union, the percentage of marijuana as the primary reason for entering treatment increased by 200 percent from 1999 to 2006, and currently stands at around 30 percent of all admissions.16 The Netherlands has the highest rate of marijuana addiction in Europe.17

Marijuana and Driving

In the past decade, researchers from all corners of the world have documented the problem of marijuana use and driving.18,19,20,21,22,23 Linked to deficits in the parts of the brain that are important for driving, including the impairment of motor coordination and reaction time, a widely-cited article in the British Medical Journal from 2012 concluded that marijuana use doubles the risk of car crashes.24

Another recent meta-analysis of nine studies found that marijuana “…use by drivers is associated with a significantly increased risk of being involved in motor vehicle crashes.”25

25 Li, M., Brady, J., DiMaggio, C., Lusardi, R., Tzong, K. and Li, G. (in press). Cannabis use and motor vehicle crashes. Epidemiologic Reviews.

26 Meier et al. (2012). Persistent cannabis users show neuropsychological decline from childhood to midlife. Proceedings of the National Academy of Sciences.

27 Fergusson, D. M. and Boden, J. M. (2008), Cannabis use and later life outcomes. Addiction, 103: 969–976.

28 Macleod, J.; Oakes, R.; Copello, A.; Crome, I.; Egger, M.; Hickman, M.; Oppenkowski, T.; Stokes-Lampard, H.; and Davey Smith, G. Psychological and social sequelae of cannabis and other illicit drug use by young people: A systematic review of longitudinal, general population studies. Lancet 363(9421):1579-1588, 2004.

29 Ellickson, P.L.; Martino, S.C.; and Collins, R.L. Cannabis use from adolescence to young adulthood: Multiple developmental trajectories and their associated outcomes. Health Psychology 23(3):299-307, 2004.
30 National Institute on Drug Abuse (NIDA). (2011). Research Report Series: Cannabis Abuse. Accessed November 2011 at http://www.drugabuse.gov/ResearchReports/Cannabis/cannabis4.html

Marijuana use and Performance at School and on the Job

One of the most well designed studies on marijuana and intelligence, released in 2012, found that marijuana use reduces IQ by as much as eight points by age 38 among people who started using marijuana regularly before age 18 but then stopped.26 Other studies have found that marijuana use is linked with dropping out of school, and subsequent unemployment, social welfare dependence, and a lower self-reported quality of life than non-marijuana abusing people.27

According to the U.S. National Survey on Drug Use and Health, youth with poor academic results were more than four times as likely to have used marijuana in the past year than youth with an average of higher grades. This is consistent with an exhaustive meta-analysis examining four dozen different studies by Macleod and colleagues, published by Lancet, who found that marijuana use is consistently associated with reduced grades and a reduced chance of graduating from school.28 Ellickson and colleagues at the RAND Corporation surveyed almost 6,000 students aged 13 to 23 and found that the teens who smoked cannabis from once a week to monthly at age 13, decreased their abuse by age 18, and as young adults smoked 3 to 10 times a year, lagged behind all other groups in earnings and education when resurveyed at age 29.29

In addition, studies have linked employee marijuana use with “increased absences, tardiness, accidents, workers’ compensation claims, and job turnover.”30

Health Recap

To recap, the science is emerging on the effects of marijuana, but we can say with some certainty that marijuana use is significantly linked with:

· Addiction

· Heart and Lung Complications (the jury is out on a connection to lung cancer, though)

· Mental Illness

· Car Crashes

· IQ loss and poor school outcomes

· Poor quality of life outcomes

· Poor job performance

Science has learned more about marijuana in the past twenty years than in the preceding two hundred. Ironically, however, there has been a major incongruence between the scientific knowledge gained and the public’s understanding of the drug. People often refer to their own experiences with marijuana rather than what scientific data has taught us. It is important to be aware of the growing scientific literature about a drug that is widely misunderstood.

Source: www.drugree.org. Article by Dr. Kevin Sabet, Assoc. Professor University of Florida

Alan Markwood
June, 2012

Introduction

Confusion about whether a “gateway” effect is part of young people’s development of substance use is not surprising, given the wide variety of interpretations of “gateway effect.” Also, in discussions of gateway drug use marijuana plays a key role, and marijuana itself is widely misunderstood. Some clarification is needed, starting with marijuana and then the concept of gateway drug use.

Perceptions of Marijuana

There are a number of aspects of marijuana that have been poorly understood or misunderstood. A number of reasons can be given for such misunderstandings, including:

1. Increase in average potency of marijuana over the past 3-4 decades. The potency of marijuana’s primary psychoactive ingredient, THC (tetrahydroannabinol), has at least doubled in the past fifteen years. Going back thirty years, the potency of marijuana typically smoked in the U.S. may have been a third or less of average current potency. Effects of the drug that were imperceptible or mild for most users in the 1970s and 1980s are becoming more severe and more common.

2. Efforts by legalization advocates to present marijuana as being relatively harmless. Advocacy for legalizing marijuana cannot succeed unless marijuana is believed to have only mild negative effects (at worst) on marijuana users and on communities as a whole. So, whenever advocacy for marijuana legalization is prevalent, along with it come statements minimizing the magnitude of any problems associated with marijuana use.

3. Differences between marijuana’s method of acting and the more common patterns of other illicit drugs. Marijuana is a fat-soluble drug, unlike most others typically used. Rather than just circulating in the bloodstream, and quickly clearing from the body after use, THC is absorbed into fatty tissue in various parts of the body, and only slowly is eliminated. Four relatively unique effects based on this are the lingering effects, potential for unending effects, low overdose impact, and blunting of withdrawal symptoms.

a. Lingering Effects: Studies have shown that while a perceived “high” from marijuana may last about two hours after use, residual impairments of various skills can linger up to 24 hours.

b. Potential for Unending Effects: With a half-life of 3-4 days after using marijuana, THC can actually be continually affecting a person if the person’s rate of marijuana use exceeds their rate of elimination of THC from their body..

c. Low Overdose Impact: Because THC goes partly into fatty tissue rather than all circulating in the blood, there is typically little permanent damage from a single heavy dose, and marijuana overdose deaths don’t occur.

d. Blunting of Withdrawal Symptoms: Because THC is eliminated so slowly from the body, symptoms of withdrawal when marijuana use stops can be less

apparent than is the case for some other drugs. This has contributed to a perception of lack of addictive potential, but as average THC content has increased, withdrawal symptoms have become more common. Scientifically, the fact that some users become addicted has been established beyond doubt. As stated by NIDA (the National Institute on Drug Abuse), “Estimates from research suggest that about 9 percent of users become addicted to marijuana; this number increases among those who start young (to about 17 percent) and among daily users (25-50 percent).”

4. Impact of marijuana on users’ perception, memories, and judgment/decision-making skills. The hallmark short-term effects of marijuana use include “distorted perceptions, memory impairments, and difficulty thinking and solving problems” (NIDA). So, if a marijuana user (especially one with frequent and/or heavy use) is asked during or after use about any negative effects, they often may have forgotten or not noticed in the first place any decrease in mental skills under the influence. The accuracy of self-reports about marijuana use is spotty, and omissions are likely, even if the person giving the report is himself/herself convinced of its accuracy.

Gateway Phenomenon Described

One aspect of marijuana use that has been consistently misunderstood has to do with the ways that it does or doesn’t function as a “gateway” drug. Before discussing how it does function as a gateway drug, and implications of that, let’s review some of the many ways in which one’s definition of “gateway” may not apply to marijuana.

* If gateway means that marijuana is typically the first drug used, marijuana isn’t a gateway drug. Alcohol would better fit that definition.

* If gateway means that marijuana is always the first drug used among all “scheduled” (controlled) drugs, marijuana isn’t a gateway drug. Marijuana is very often the first illicit drug used by those who use one or more illicit drugs, but some others can also be common. During the past decade, the number of instances of prescription drugs being the first controlled substance used (with alcohol and tobacco not being included in the definition of “controlled substance”) has grown rapidly, apparently due to the rapid growth of prescriptions for narcotic drugs.

* If gateway means that marijuana is always in a sequence that starts with alcohol or tobacco, then marijuana, and then other drugs … marijuana isn’t a gateway drug. That sequence is common, but so are a few others.

* If gateway means that most young people who use marijuana go on to use other drugs, marijuana is not a gateway drug. The truth is that although hardly anyone starts use of a “post-gateway” drug like cocaine, meth, or heroin without having already used either alcohol, tobacco, marijuana, or some combination among those three gateway drugs, the majority of young people who have used marijuana will not go on to other illicit drugs. The real gateway effect isn’t that everyone who reaches a gate goes through it, but that: 1) Any who have reached the other side are very likely to have come through a gate, and 2) Any who turn away before reaching the gate are extremely unlikely to later find themselves beyond the gated wall. In other words, 1) Most of the people who use cocaine, meth, or

heroin (or some other “post-gateway” illicit drugs) have used marijuana, either concurrently or previously, and 2) Among the people who have never used marijuana, use of any “post-gateway” drugs is extremely rare.

Does this description of “gateway drug use” mean something important enough to merit sorting through all the potential confusion in order to understand it? I’d say it does. First, I’d define a gateway drug as the first drug of abuse used regularly (at least once a month) by a young person who begins regular use of a substance. That definition fits across most times and places, while the following two sentences are more specific to the United States and to the past ten years. A person’s gateway drug could be alcohol, tobacco, marijuana, or inhalants. Rarely it could be some other drug, particularly a prescription or over the counter drug used for psychoactive effect rather than as directed.

The current prevalence of teen use of each of the listed substances in the United States gives an indication of the relative role of each as a gateway drug, even though the picture is complicated by the many instances of multi-drug use. According to the national “Monitoring the Future” findings, the “30-day prevalence of use” by 10th grade students in 2011 for: alcohol was 27.2%; tobacco/cigarettes was 11.8%; tobacco/smokeless was 6.6%; marijuana was 17.6%; and for inhalants was 1.7%. Youth use of tobacco used to be (in the 1990’s) consistently between the alcohol prevalence and marijuana prevalence, but youth tobacco use decreased a great deal in the past decade, while teen use of marijuana decreased until about five years ago and has since risen.

Now, revisit the statement that,

“The real gateway effect isn’t that everyone who reaches a gate goes through it, but that: 1) Any who have reached the other side are very likely to have come through a gate, and 2) Any who turn away before reaching the gate are extremely unlikely to later find themselves beyond the gated wall.”

Although quantifying “extremely” can vary according to things like what’s defined as the “gateway” substance(s), or the population studied, the percentages are usually more than 90% and often near 99%. As an example, consider data from a 2002 study by the U.S. Dept. of Human Services, Substance Abuse and Mental Health Services Administration, Office of Applied Studies (Gfroerer, J. C., Wu, L.-T., & Penne, M. A. (2002). Initiation of Marijuana Use: Trends, Patterns, and Implications (Analytic Series: A-17, DHHS Publication No. SMA 02-3711). Rockville, MD: Substance Abuse and Mental Health Services Administration, Office of Applied Studies.) In this study, the “gateway” was only marijuana use, and among the results studied were the extent to which age at first marijuana use was related to later use of either heroin, cocaine, or “any psychotherapeutic” (prescription) drug used “non-medically”. These results were based on information from adults age 26 or older who participated in the government’s main national survey of adult substance use. Two of the findings shown in the results were:

1. Among adults who had never used marijuana, only 0.1% (that is, one-tenth of a percent) had used heroin, only 0.6% had used cocaine, and only 5.1% had used prescription drugs for non-medical (i.e., “recreational”) effect.

2. For each substance (heroin, cocaine, or prescription drugs used for subjective effect rather than medically), there was consistently a pattern of decreasing

prevalence of use as age of first marijuana use categories went from “14 or younger” to “15-17”, then “18-20”, then “21 or older”, and finally “never used marijuana.” In regard to cocaine use, for example, the percent of people who had used cocaine, among the people who started marijuana use at age 14 or younger, was 62.0%. Looking at all who started marijuana use at ages 15-17; then 18-20; then 21 or older; and finally those who had never used marijuana, the respective percent who used cocaine went from 40.9% to 28.8%, then 16.4%, and finally 0.6% among those who never used marijuana.

In this particular example, “Any who turn away before reaching the gate are extremely unlikely to later find themselves beyond the gated wall,” means that only 0.6% of those who had never used marijuana later used cocaine (343,021 divided by 57,170,147). And, “Any who have reached the other side are very likely to have come through a gate” means that of the 1,341,359 adults who had used cocaine in their lifetime, nearly 75% (998,338) had previously used marijuana.

Gateway Phenomenon Applied

The prevalence of alcohol use and of other drug use increases as a cohort of youth (e.g., those born between 1995 and 1998) move through their junior high and high school years. During those years, alcohol, tobacco and marijuana are the drugs most prevalent among youth, but the majority of youth don’t regularly (at least once a month) use any of those gateway substances. Of those who do regularly use at least one, most use only one. However, regular use of just one raises the odds of use of a second, and each additional drug used raises the odds that even more will be used. In other words, drug use raises the odds of more drug use. What is behind this pattern of use?

Once a single gateway substance is regularly used, a number of potential risks based on use of that substance can strongly affect whether regular use of a second (or third, etc.) substance is begun. Here is one list of many possible ways that regular use of one gateway substance can increase risk of other drug use:

1. The lack of observed major negative effects on oneself and on peers who are using a substance can seem to validate a young person’s perception that trying to get high isn’t as dangerous as many adults warn it is. Some youths may recognize that heavy use of a substance or use of more than one substance raises the risk, but other youths may not see this.

2. Even if risk is perceived, it can be overtaken by the appeal of repeating a “high”, especially to the extent that dependency is developing. The sensation of being high can be extremely motivating, especially to persons more vulnerable to that effect. An extension of this is that in some instances regular use of one substance may chemically “prime” the brain for use of other substances that affect the brain similarly. The existence of this kind of “priming” has been documented, but how often this happens is not yet known.

3. When a young person connects with a substance-using peer group:

a. His/her perception of peer norms can be skewed toward drug use.

b. His/her access to a variety of substances may be facilitated by the group.

4. Depending on the interaction of a) substance(s) used; b) user vulnerability; and c) frequency of use, gateway substance use can impair key aspects of thought involved in decision making about other drug use. Marijuana is particularly suited to this effect due to the combination of its subtle, yet measurable impact on thought and the longer amount of time it remains in a person, compared to drugs that aren’t fat-based.

With the above discussion in mind, consider one key question about marijuana’s role as a gateway drug: Given that there is some gateway effect between marijuana use and use of other drugs, is that effect due to marijuana use causing increased risk of other substances (whether chemically or via situational factors such as interaction with other drug users), or due to marijuana use being an indicator of a young person who, for other reasons, is at elevated risk for a variety of problems? Recent research (e.g., “Is It Important to Prevent Early Exposure to Drugs and Alcohol Among Adolescents?”, Odgers et al, Pscyhological Science, v 19, n10, pp 1037-1044) shows that both are true: Some youth have problems early in life that put them at future risk of multiple other problems, but:

1) An equal (or greater) number of youth don’t have such problems, but become likely to have other youth or adult problems if they begin substance use at an early age.

2) Youth who are already at higher risk due to problems early in life and who begin substance use early in adolescence become even higher risk for a variety of problems.

3) The above observations hold true even if just alcohol is used by young teens, but the effects are worse for those with “poly-substance” (usually alcohol and marijuana) use.

So, regarding causation, research results suggest the following:

1. Some youth are more at risk of multi-substance use even before they start regular use of a gateway drug, but their risk increases with regular use of a gateway substance.

2. Three dimensions of youth alcohol, marijuana, or other gateway substance use that can greatly heighten the probability of multi-substance use, drug dependence, and a number of other problems are how early in life the regular use begins, how frequently the substance is used, and how heavy a “dose” is typically used.

3. The earlier that a teen or pre-teen starts use of marijuana (or alcohol), and the heavier and more frequent their use, the greater the likelihood that their rapidly increasing risk of multi-substance use and other problems is at least partly (and perhaps substantially) caused by the gateway substance use.

The term “causation” as used in this discussion doesn’t mean that use of one gateway substance dooms a person to using additional drugs: typically more youth do not progress to other drug use than do. However, for many who do progress, use of the first substance and the results of that use often can make the difference. The most typical pattern is alcohol as the first substance, but marijuana can be that first substance and in many cases is at least the first illicit drug used. In either case, marijuana use serves as a potential gate to other use. Most youth may not proceed through that gate, but the percent of marijuana users among those who go on is very high. So is the percent of alcohol users. The odds multiply if both those substances are used. Some people may prefer to say that marijuana

use “can contribute to risk for other drug use,” to emphasize that there are multiple factors involved, and that marijuana use certainly doesn’t guarantee any further use of any drug. Such a view is most appropriate when considering one person’s experiences. There is variation among individuals, so in regard to any one person, the role of marijuana use in the development of other drug use may not be clear. However, when large groups of young people are considered, there is no doubt that increases in marijuana use will result in more use of other drugs among that group or population. Increased marijuana use causes much of the increase in other drug use, by multiplying the risk already present at the start of regular use of marijuana.

In the 1970’s public opinion about marijuana was biased toward the negative. Today, with the (previously discussed) confusion about marijuana effects, public opinion is becoming very biased in the other direction. The toll taken on individuals and on society by marijuana use is growing at the same time public perception of individual and societal damage from marijuana is decreasing. One of the least well understood aspects of marijuana’s potential effect on individuals and marijuana’s measurable negative effect on communities is the way in which marijuana use can play a causal role in the development of other substance use. It is not “the” cause of other use, but is one of the most powerful contributing causes, in terms of increased risk to the individual and increased damage to populations. Marijuana users and others in favor of allowing use may continue to deny this gateway effect, but their denials don’t invalidate the consistent findings of objective study of population-wide substance use patterns.