What Marijuana Might Do to Your Brain

The latest research suggests a link between the drug and laziness. But is the occasional puff okay?

The stoner character may be more than stereotype: Smoking pot may actually make you lazy. Occasional marijuana use can affect your motivation, according to a recent study from Harvard Medical School. 

Out of 40 college students, the half who smoked pot once or twice a week for a few months showed more changes in the brain areas regulating emotion, mental illness, and motivation than the drug-free undergrads. “Your motivation levels determine whether or not you get out of bed in the morning,” says study coauthor Anne Blood, Ph.D. "And we're seeing some pretty convincing changes in these regions.” 

The changes the researchers observed were directly correlated with consumption, meaning the more marijuana a student smoked, the more abnormal the shape, volume, and density of the brain region was. “These people are regular users, but they’re not having problems in their life because of marijuana," Blood says. "By clinical standards, a recreational user is smoking an average of six joints a week.” 

Blood acknowledges that one study doesn’t prove anything, but she urges marijuana users to proceed with caution. “For someone who smokes once a month, it may take three weeks for [marijuana] to leave your system,” says Blood. “The drug is presumably still having some impact on what the brain is doing.”

While we wait for more research, here's what we do know right now: Pot can have both positive and negative effects on your health.