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Pot smoking not tied to middle-age mental decline

In the study, past and current users of marijuana actually scored higher on memory tests than those who didn't use the drug.

By ReutersWed, Jan 04 2012 at 12:13 AM EST
 7

A marijuana supporter smokes during a protest in Toronto in 2008.
Photo: ZUMA Press
Middle-aged adults whose memories have grown hazy can't blame occasional pot smoking or other light illicit drug use for their forgetfulness, according to a British study, although experts warn heavy, prolonged use could harm mental functions.
 
The study, carried in the American Journal of Epidemiology, tested the mental function and memory of nearly 9,000 Britons at age 50 and found that those who had used illegal drugs as recently as in their 40s did just as well, or slightly better, on the tests than peers who had never used drugs.
 
Marijuana was by far the most common indulgence for the participants — who were surveyed at age 42 about current or past drug use, then tested at age 50 — with six percent saying they had used it in the past year, while one-quarter said they had ever used it.
 
Other drugs they were asked about included amphetamines, LSD, hallucinogenic mushrooms, cocaine and ecstasy — with anywhere from three percent to eight percent of study participants saying they'd ever used those drugs.
 
"Overall, at the population level, the results seem to suggest that past or even current illicit drug use is not necessarily associated with impaired cognitive functioning in early middle age," said lead researcher Alex Dregan, of King's College London.
 
"However, our results do not exclude possible harmful effects in some individuals who may be heavily exposed to drugs over longer periods of time."
 
A small subset of participants who said they had ever been treated for their drug use, which could suggest heavy or addicted drug use, did not fare as well cognitively at 50, but there were too few of them to draw meaningful conclusions, the study authors noted.
 
Dregan's team used data on 8,992 42-year-olds participating in a UK national health study, who were asked if they had ever used any of 12 illegal drugs. Then, at the age of 50, they took standard tests of memory, attention and other cognitive abilities.
 
Overall, the study found, there was no evidence that current or past drug users had poorer mental performance. In fact, when current and past users were lumped together, their test scores tended to be higher.
 
But that advantage was small, the researchers said, and might just reflect another finding — that people who'd ever used drugs generally had a higher education level than non-users.
 
"In a Western population of occasional drug users, this is what you'd expect to see," said John Halpern, a psychiatrist at Harvard Medical School and McLean Hospital in Belmont, Massachusetts, who has studied the potential cognitive effects of drug use.
 
"In some ways, this is not surprising. The brain is resilient."
 
Though some studies have found that drugs like marijuana and cocaine may cloud thinking, memory and attention in the short term, the current findings support the notion that those effects may be temporary, Dregan's team said.
 
Halpern noted that work focusing on people who have smoked pot regularly for years showed that once they stop the drugs, their deficits on cognitive tests improve after a month.
 
Still, he said this should not be taken as an endorsement of drug use, noting that the current study did not rule out the possibility of lasting negative cognitive effects from heavy, prolonged drug use.
 
(Reporting from New York by Amy Norton at Reuters Health; Editing by Elaine Lies and Yoko Nishikawa)
 
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anonymous
not in agreement 01/17/2012 12:39 PM

What about the report I read recently that heavy pot-users, even for no longer than 2 years, had a real possibility of developing schizophrenia...and that the schizophrenia was non-reversable??Why do we not hear more about that study??

anonymous
Pudizzle 01/05/2012 13:53 PM

It's all fun and games until you trip out or you get anxiety. While agree the occassional toke will probably not cause too much detriment to the brain/mind, I am confident that chronic use over a prolonged period of time will cause changes in your congnative behavior. A person's mind can only stand so much mind alteration before the alarm bells go off!

anonymous
Just Me 01/04/2012 17:57 PM

When will people realize that there are very very successful and extremely intelligent people who currently are MJ users, though maybe not admittedly, but users none the less. They wake up everyday and go to their jobs and the others around them are none the wiser.

anonymous
Anonymous 01/04/2012 20:06 PM

Sadly, you could actually say the same about heroin. People only notice out-of-control users that make headlines for something very dangerous, very embarrassing, and always very stupid, or one may notice subtly affected people if they're very close to them...maybe. So yeah, most people's experiences with addicts are isolated incidents, flukes, or what 12-steppers call slips, or maybe the guy in the middle of the street angrily yelling at a 4th floor window at 3am is just a jerk. If all of.... More

anonymous
Anonymous 01/05/2012 10:04 AM

You could say the same about heroin if you wanted to completely stray from the topic. What are you talking about with "smart ones ignoring the world so everything doesn't seem so futile" yada yada? What about the guy who just worked an 10 hour day at a job he loves and wants to burn one and play Xbox? Life isn't futile to him. There are no smart users and stupid users, just users using for whatever reason but the difference between pot and most of the other illicit drugs is pot users aren't.... More

anonymous
Jon 01/04/2012 16:41 PM

In other words, the drugs themselves make basically no difference. Those that occasionally indulge in pot are probably just, on average, a little smarter than most. Those that end up in drug treatment, a little less bright. That would be my interpretation of this data, anyway.

anonymous
Anonymous 01/06/2012 13:06 PM

MJ is not physically addictive. those who "end up" in treatment for MJ use are habituated to it, just like I'm habituated to 10PM bedtime. I was a chronic smoker for much of my considerable adult life.. One day I decided to try life without it. No probs, game over and 2 years and no withdrawal later, I am still pot free. I wasn't an effort, mentally or physically. Those who "end up" in rehab for pot use likely f=have psychological issues beyond their smoking and were self- medicating. Read.... More

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