Stoners lose 8-points of IQ
they found that those who persistently used cannabis – smoking it at least four times a week year after year through their teens, 20s and, in some cases, their 30s – suffered a decline in their IQ. … The more that people smoked, the greater the loss in IQ. … researchers found that individuals who started using cannabis in adolescence and then carried on using it for years showed an average eight-point IQ decline…. “This work took an amazing scientific effort. We followed almost 1,000 participants, we tested their mental abilities as kids before they ever tried cannabis, and we tested them again 25 years later after some participants became chronic users.”
That’s half a standard deviation, down from 100 if average to 98. Could explain the under-achievement attributed to stoners.
Acidic review of Debt: The First 5,000 Years
the accumulation of anecdotes does not add up to an explanation, and certainly not one that would overturn the existing wisdom on the subject, conventional or otherwise. It is a story told almost entirely in the realm of political and moral philosophy