If you smoke a lot of marijuana on a regular basis, you may have some problems with your verbal memory in middle age. That’s according to new research published Monday in the journal JAMA Internal Medicine.
Researchers at the University of Lausanne in Switzerland examined the effects of long-term marijuana use by studying the marijuana consumption habits of nearly 3,400 Americans over a 25-year period. Study participants were assessed on cognitive function in the areas of memory, focus, decision making and so forth, as reported by The Washington Post.
Results showed that participants who smoked marijuana each day for five years or more had lower verbal memory scores (ability to remember words) by middle age than those who didn’t smoke marijuana, or those who smoked less regularly.
“We found a dose-dependent independent association between cumulative lifetime exposure to marijuana and worsening verbal memory in middle age,” researchers wrote in the study.
Although marijuana exposure was linked to declines in verbal memory, heavy marijuana use did not appear to affect other cognitive functions, such as mental processing speed, focus and planning.
Researchers are not sure why marijuana might affect verbal memory, but they think it may have something to do how THC (the psychoactive chemical in marijuana) affects the way information is processed in the hippocampus region of the brain, according to Live Science.
It should be noted that these study results found a correlation between heavy marijuana use and verbal memory declines in middle age, but it does not establish causation. The study also faced a number of limitations that may have affected results, including that marijuana use was self-reported and cognitive tests were only performed once, at the end of the study.
For each 5 years of past exposure, verbal memory was 0.13 standardized units lower, corresponding to a mean of 1 of 2 participants remembering 1 word fewer from a list of 15 words for every 5 years of use.
In conclusion, this study, while showing some decline in verbal memory, is hardly a profound loss of cognitive function in the verbal cortex. We’re more inclined to be worried about losing our car keys, which is on almost a daily basis. So, if you don’t mind ‘perhaps’ losing 3 words in 15 years, by all mean, toke on friends.