Maybe this explains blue and the rest of the loony left.
According to the British newspaper The Telegraph:
Researchers found persistent users of the drug, who started smoking it at school, had lower IQ scores as adults.
They were also significantly more likely to have attention and memory problems in later life, than their peers who abstained.
Furthermore, those who started as teenagers and used it heavily, but quit as adults, did not regain their full mental powers, found academics at King’s College London and Duke University in the US.
Professor Terrie Moffitt, of KCL’s Institute of Psychiatry, who contributed to the study, published in the journal Proceedings of the National Academy of Sciences, said “persistent users” who started as teenagers suffered a drop of eight IQ points at the age of 38, compared to when they were 13.
Persistent users meant those who used it during at least three of the ages from 18 to 38, and who said at each occasion they were smoking it on at least four days a week.
She said: “Adolescent-onset #$%$ users, but not adult-onset #$%$ users, showed marked IQ decline from childhood to adulthood.
“For example, individuals who started using #$%$ in adolescence and used it for years thereafter showed an average eight-point IQ decline.
“Quitting or reducing #$%$ use did not appear to fully restore intellectual functioning among adolescent-onset former persistent #$%$ users,” she said.
Although eight points did not sound much, it was not trivial, she warned.
It meant that an average person dropped far down the intelligence rankings, so that instead of 50 per cent of the population being more intelligent than them, 71 per cent were.