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Marijuana doesn’t cause teens’ IQ drop, study says.
Scientists from UCLA and the University of Minnesota analyzed data from 290 sets of twins, with one twin who had used marijuana and one that had not. No association between pot use and IQ declines was found in this set of data, as reported by The Denver Post.
Scientists also analyzed data from more than 3,000 participants who were given intelligence tests at ages nine to 12 (before they used marijuana), and then again at ages 17 to 20.
Six IQ-related test scores indicated largely no difference between the intellects of heavy marijuana users and non users, although pot users did test lower than non users in vocabulary and general knowledge, areas associated with “crystallized intelligence,” as reported by Meta Science News.
Tests that measured “fluid intelligence” like abstract reasoning and problem solving showed no major differences between marijuana users and non users.
Per Meta Science News:
The authors noted, however, that in one of the two studies, the baseline IQ scores of eventual users were already significantly lower in the affected areas.
Here, marijuana use does not precede cognitive decline, and they point out prior evidence that suggests other factors such as behavioral disinhibition and conduct disorder that may predispose individuals to both lower IQ and substance use.
These findings agree with previous studies that also found no relationship between heavy pot use and decreased intelligence.
Agencies/Canadajournal
