Casual use of marijuana can produce changes in parts of the brain associated with emotion and motivation, according to a new study.
The study suggests that moderate use of marijuana can have detrimental effects often associated with dependence, according to The Washington Post.
"People think a little recreational use shouldn’t cause a problem, if someone is doing OK with work or school," study co-author Hans Breiter told Northwestern University’s Science Newsline, according to the Post. "Our data directly says this is not the case."
Researchers at Northwestern University and Massachusetts General Hospital studied 20 users, ages 18 to 25, over a three-month period who said they smoked up to four times a week and consumed a total of about 11 joints, according to the Post. That group was compared to a pool of 20 non-marijuana smokers.
The results showed that even the lightest users — those who reported smoking just once a week — exhibited differences in their brains.
The study analyzed changes in the brain itself, but not the behavior of its subjects, according to the Post. Independent experts said the study shows that even limited use can have negative impacts on the brain, but that larger studies are needed to determine the long-term impact of casual to moderate marijuana use, according to The Associated Press.
The study comes as states are decriminalizing and legalizing the medicinal and recreational use of marijuana and potentially heightening the importance of the report's findings.
"What we think we are seeing here is a very early indication of what becomes a problem later on with prolonged use," Breiter said.
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