The cliché of the slow-witted stoner doesn't reflect reality.
It only takes three days of sobriety for a serious pothead's cognitive functions to fully recover, a new study has found.
Researchers in the US looked at 69 studies, including more than 2000 frequent cannabis users, conducted over four-and-a-half decades to see if it really did make people slow and clumsy.
They found while "Small cognitive effects were associated with heavy/frequent cannabis use among adolescents and young adults, the results suggest they faded substantially with abstinence longer than 72 hours."
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Cognitive functions include memory, attention, information processing and motor functioning.
"[The] results indicate that previous studies of cannabis in youth may have overstated the magnitude and persistence of cognitive deficits associated with use," the authors wrote in the study, published in journal JAMA Psychiatry.
They say researchers in the past may have inadvertently been measuring the effects of cannabis withdrawal, rather than the long-term effects of cannabis itself.
The research didn't look into whether long-term regular cannabis use had mental health risks, as some previous research has found.