I manage and am an Actuary for an insurance company. So I work with a lot of very smart, math oriented, introverted, nerds basically. There is a very distinct trend I see, none of them drink. However, they do like to smoke weed. They all have very good memories and the ability you have very long critical thought. So I think scapegoating stoners as not having good memories and as idiots is naive. All things have different reactions to people, like some drinkers are fun to be around and some are just jerks. Some of the smartest people I know go home at night and smoke and are ready the next day to complete some of the most complex problems known to man (healthcare).
So to paint a broad brush into grouping everyone as the same because of a common trait, is a fools game.