Study: Regular marijuana use linked to problems in midlife

A study that followed children from birth to midlife found that heavy marijuana users who smoked for years often fared worse as adults than their parents: Many ended up in jobs that paid less, required fewer skills and were less prestigious.

That wasn’t so much the case for other people.

“The rest of the people in the study who were not regular and persistent cannabis users ended up in a higher social class than their parents,” said Magdalena Cerda, lead investigator and associate professor at the University of California, Davis.

The study, published Wednesday in the journal Clinical Psychological Science, also found that marijuana users who smoked at least four times a week experienced more financial difficulties, such as problems with debt and food insecurity, than their parents. Their lives were fraught with more social problems, too.

“They experienced more antisocial behaviour at work such as lying to get a job or stealing money and more relationship problems such as intimate partner violence or controlling behaviour towards their partner,” Cerda said.

Other studies have associated heavy and persistent marijuana use with problems in adulthood but haven’t always ruled out other factors. This research tried to do that by tracking and comparing variables such as intelligence, family structure, gender, ethnicity, parental substance abuse, criminal convictions and antisocial behaviour and depression in childhood.

In accounting for so many variables, researchers made the study’s conclusions stronger, Cerda said, acknowledging that there may be unknown factors that they didn’t track.

Dr. Colin Roberts, a paediatric neurologist at Oregon Health & Science University and a member of Oregon’s Cannabis Research Task Force created to study medical marijuana, said the findings are worth considering.

“It’s a good study,” Roberts said. “They established an association that’s pretty compelling.”

The study’s sample size, almost 950 people, also gives it heft, he said.

The study is based on four decades of data collected in New Zealand, where marijuana is illegal. Investigators have been following people born between 1972 and 1973 in Dunedin, the second largest city on the South Island. The participants in the study come from a range of socio-economic classes, from professionals to unskilled labourers, who had physical, psychological, social and financial assessments at birth and ages 3, 5, 9, 11, 13, 15, 18, 21, 26, 32 and 38.

“There was a large number of people that were looked at which is really important,” Roberts said. “We can’t do studies like this in the U.S. because it’s really hard to collect information on people over that period of time. We don’t have a central source for people’s medical records.”

The study analyzed the data from the childhood evaluations to determine pre-existing conditions that might cause financial or social problems later in life. Then it evaluated the marijuana use of people starting at age 18 through 38 and financial and social problems at age 38. It found that 15 percent were frequent users, which they defined as smoking marijuana four or more times a week.

The longer those people smoked, the worse their problems in midlife.

That’s consistent with what professionals like Dr. Kevin Hill see in their practices. He’s the author of “Marijuana: The Unbiased Truth about the World’s Most Popular Weed” and an addiction psychiatrist at McLean Hospital, an affiliate of Harvard Medical School in Massachusetts.

“This paper supports what we see clinically,” Hill said. “If you’re using at a level that’s consistent with cannabis addiction, you will have problems in multiple spheres – work, school and relationships.”

Not everyone who smoked marijuana four times or more a week for years experienced downward mobility and not everyone who abstained fared better than their parents. But a higher proportion of the former group – nearly 52 percent – had a worse outcome compared with 14 percent of the latter.

The study also looked at alcohol use. Those with an alcohol dependency experienced more social problems than their parents and landed lower-paying jobs. But the marijuana users who were dependent on the drug had even more financial worries than those addicted to alcohol.

“Those of us in the field know that cannabis is potentially dangerous but the same argument should be made with alcohol,” Hill said. “We have 22 million Americans who used cannabis last year and yet we rarely talk about cannabis being dangerous and we should.”

Yet he cautioned that people who are dependent on marijuana remain in the minority, just as those who abuse alcohol are.

Alcohol remains the bigger problem because it’s more widespread, Cerda said, but she added that the increasing acceptance of marijuana could increase the cost to society. Oregon is one of 23 states where marijuana is legal for medical use and four states that have approved recreational marijuana use.

The study points to a need for investment in prevention and treatment, she said.

“If we do that, it may have long-term consequences for the potential burden that this may place on communities, families and on the broader social welfare system,” Cerda said.

Source:   23rd March 2016

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