The devastating consequences of marijuana use


Did you know that….

• The Drug Abuse Warning Network (DAWN), a system for monitoring the health impact of drugs, estimated that, in 2001, marijuana was a contributing factor in more than 110,000 emergency department visits in the United States, with about 15 per cent of the patients between the ages of 12 and 17, and almost two-thirds male.

• In 1999, the US National Institute of Justice’s Arrestee Drug Abuse Monitoring Program (ADAM), which collects data from 34 sites on the number of adult arrestees testing positive for various drugs, found that, on average, 39 per cent of adult male arrestees and 26 per cent of adult female arrestees tested positive for marijuana.

• ADAM collected data on juvenile arrestees in nine sites and found that marijuana was the most commonly used drug among these youths. On average, 53 per cent of juvenile male and 38 per cent of juvenile female arrestees tested positive for marijuana.

• Through its effects on the brain and body, marijuana intoxication can cause accidents. Studies show that approximately 6 to 11 per cent of fatal accident victims test positive for THC. In many of these cases, alcohol is detected as well.

• In a study conducted by the US National Highway Traffic Safety Administration, a moderate dose of marijuana alone was shown to impair driving performance; however, the effects of even a low dose of marijuana combined with alcohol were markedly greater than for either drug alone. Driving indices measured included reaction time, visual search frequency (driver checking side streets), and the ability to perceive and/or respond to changes n the relative velocity of other vehicles.

• Marijuana use has been shown to increase users’ difficulty in trying to quit smoking tobacco. This was recently reported in a study comparing smoking cessation in adults who smoked both marijuana and tobacco with those who smoked only tobacco. The relationship between marijuana use and continued smoking was particularly strong in those who smoked marijuana daily at the time of the initial interview, 13 years prior to the follow up interview.

• A study of 450 individuals found that people who smoke marijuana frequently but do not smoke tobacco have more health problems and miss more days of work than non-smokers do. Many of the extra sick days used by the marijuana smokers in the study were for respiratory illnesses.

• A study comparing 173 cancer patients and 176 healthy individuals produced strong evidence that smoking marijuana increases the likelihood of developing cancer of the head or neck, and that the more marijuana smoked, the greater the increase. A statistical analysis of the data suggested that marijuana smoking doubled or tripled the risk of these cancers.

• Marijuana has the potential to promote cancer of the lungs and other parts of the respiratory tract because it contains irritants and carcinogens. IN fact, marijuana smoke contains 50 per cent to 70 per cent more carcinogenic hydrocarbons than does tobacco smoke. It also produces high levels of an enzyme that converts certain hydrocarbons into their carcinogenic form, levels that may accelerate the changes that ultimately produce malignant cells.

• Some adverse health effects caused by marijuana may occur because THC impairs the immune system’s ability to fight off infectious diseases and cancer. IN laboratory experiments that exposed animal and human cells to THC or other marijuana ingredients the normal disease-preventing reactions of many of the key types of of immune cells were inhibited. IN other studies, mice exposed to THC or related substances were more likely than unexposed mice to develop bacterial infections and tumours.

• One study has indicated that a person’s risk of heart attack during the first hour after smoking marijuana is four times his or her usual risk. The researchers suggest that a heart attack might occur, in part, because marijuana raises blood pressure and heart rate and reduces the oxygen-carrying capacity of blood.

• Students who smoke marijuana get lower grades and are less likely to graduate from high school, compared with their non-smoking peers. In one study, researchers compared marijuana smoking and non-smoking 12th-graders’ scores on standardized tests of verbal and mathematical skills. Although all of the students had scored equally well in 4th grade, the smokers’ scores were significantly lower in 12th grade than the non-smokers scores were.

• Several studies have associated workers’ marijuana smoking with increased absences, tardiness, accidents, workers’ compensation claims, and job turnover. A study among municipal workers found that employees who smoked marijuana on or off the job reported more ‘withdrawal behaviors’ – such as leaving work without permission, day-dreaming, spending work time on personal matters, and shirking tasks – that adversely affect productivity and morale.

• Because marijuana compromises the ability to learn and remember information, the more a person uses marijuana the more her or she is likely to fall behind in accumulating intellectual, job, or social skills. Moreover, research has shown that marijuana’s adverse impact on memory and learning can last for days or weeks after the acute effects of the drug wear off. For example, a study of 129 college students found that among heavy users of marijuana, those who smoked the drug at least 27 of the preceding 30 days, critical skills related to attention, memory, and learning were significantly impaired, even after they had not used the drug for at least 24 hours. The heavy marijuana users in the study had more trouble sustaining and shifting their attention and in registering, organising, and using information than did the study participants who had used marijuana no more than 3 of the 30 previous days. As a result, someone who smokes marijuana once daily may be functioning at a reduced intellectual level all of the time.

• More recently, the same researchers showed that a group of long-term heavy marijuana users’ ability to recall words from a list was impaired 1 week following cessation of marijuana use, but returned to normal by 4 weeks. An implication of this finding is that even after long-term heavy marijuana use, if an individual quits marijuana use, some cognitive abilities may be recovered.

• Another study produced additional evidence that marijuana’s effects on the brain can cause cumulative deterioration of critical life skills in the long run. Researchers gave students a battery of tests measuring problem-solving and emotional skills in 8th grade and again in 12th grade. The results showed that the students who were already drinking alcohol plus smoking marijuana in 8th grade started off slightly behind their peers but that the distance separating these two groups grew significantly by their senior year in high school. The analysis linked marijuana use, independently of alcohol use, to reduced capacity for self-reinforcement, a group of psychological skills that enable individuals to maintain confidence and persevere in the pursuit of goals.

• Research has shown that babies born to women who used marijuana during their pregnancies display altered responses to visual stimuli, increased tremulousness, and a high-pitched cry, which may indicate problems with neurological development. During infancy and preschool years, marijuana-exposed children have been observed to have more behavioural problems and to perform tasks of visual perception, language comprehension, sustained attention, and memory more poorly than non-exposed children do. In school, these children are more likely to exhibit deficits in decision-making skills, memory and the ability to remain attentive.

• Long-term marijuana use can lead to addiction for some people; that is, they use the drug compulsively even though it often interferes with family, school, work, and recreational activities.

• According to the 2001 US National Household Survey on Drug Abuse, an estimated 5.6 million Americans age 12 or older reported problems with illicit drug use in the past year. Of these, 3.6 million met diagnostic criteria for dependence on an illicit drug. More than 2 million met diagnostic criteria for dependence on marijuana/hashish. IN 1999, more than 220,000 people entering drug abuse treatment programs reported that marijuana was their primary drug of abuse.

• Along with craving, withdrawal symptoms can make it hard for long-term marijuana smokers to stop using the drug. People trying to quit report irritability, difficulty sleeping, and anxiety. They also display increased aggression on psychological tests, peaking approximately 1 week after they last used the drug.

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