The team of scientists compared the size, shape, and density of the nucleus accumbens and the amygdala -- a brain region that plays a central role in emotion -- in 20 marijuana users and 20 non-users. Each marijuana user was asked to estimate their drug consumption over a three-month period, including the number of days they smoked and the amount of the drug consumed each day. The scientists found that the more the marijuana users reported consuming, the greater the abnormalities in the nucleus accumbens and amygdala. The shape and density of both of these regions also differed between marijuana users and non-users.
"This study raises a strong challenge to the idea that casual marijuana use isn't associated with bad consequences," Breiter said.
You can't have widespread drug use and a productive society. Sorry.