Casual marijuana use may be linked to brain abnormalities associated with emotion and motivation, according to a new study published in The Journal of Neuroscience.
About 18.9 million people in the United States recently admitted to using marijuana, making it the most common illegal drug, according to an analysis by the National Survey on Drug Use and Mental Health.
"This study raises a strong challenge to the idea that casual marijuana use isn't associated with bad consequences," Hans Breiter, who led the study, said in a statement.
Casual, or recreational, cannabis use means getting high less than four times a week on average, according to USA Today.
Researchers compared the brains of 40 Boston-area college students, age 18 to 25. Twenty of them reportedly dabbled in the drug more than once a week, and the remaining 20 had little-to-no history of marijuana use. The study found volume, shape and density changed in two brain regions - the nucleus accumbens and amygdala, which are connected to emotion, motivation and some types of mental illness.
What's more, the more these young adults were lighting up, the greater the abnormalities in these brain areas were, which in turn affected their emotions and motivations.
"People think a little recreational use shouldn't cause a problem, if someone is doing OK with work or school. Our data directly says this is not the case," Breiter, a psychiatrist and mathematician at the Northwestern University Feinberg School of Medicine in Chicago, told ScienceNewsline.
Such stress is not to be overlooked, the researchers note.
"These are core, fundamental structures of the brain," said co-senior study author Anne Blood, assistant professor of psychiatry at Harvard Medical School.
"This is a part of the brain you do not want to mess around with," Breiter added, according to the USA Today report.
Despite the risks, the general public seems to be warming to the idea of legalizing marijuana. Just this week, Colorado unveiled its first marijuana vending machine equipped with pot-infused treats for those with medical prescriptions.
