Marijuana does not substantially harm thinking skills of long-term recreational users, according to researchers at the University of California San Diego.

They analyzed 15 previously published research studies, and the only side effect found was a minimal reduction in learning and memory.

UCSD researchers evaluated the neurocognitive abilities of 704 cannabis users and 484 nonusers. In addition to learning and memory, UCSD researchers looked at participants’ simple reaction time, attention and motor and language skills.

While the studies included a wide range of marijuana users, Grant defined recreational marijuana users as those who smoke a couple of times a month to a couple of times a week.

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