Pot-smoking may have little lasting effect on the brain, research suggests

Despite fears to the contrary, recreational marijuana use apparently has little lasting effect on the brain.

UC San Diego researchers came to this conclusion after analyzing the results of 15 studies comparing brain function in cannabis users and nonusers. The study included data on nearly 2,000 people, 704 of whom ranged from heavy users to those who smoked two to three times a week for a few years.

Researchers looked at data from tests of memory, perception and reasoning, including reaction time, verbal and motor skills, and the ability to evaluate information and take action on it. Except for a small deficit in users’ learning and memory tests, results were similar in pot smokers and nonusers. The researchers question whether the minimal difference in learning and forgetting (failure to recall or recognize something) would even be noticeable in real life.

“The results provide some reassurance that if cannabis were found to be useful as a medicine, the adverse effects on the brain are likely to be minimal to nonexistent,” says the lead author, Dr. Igor Grant, director of the Center for Medicinal Cannabis Research at UC San Diego. The study was published in July’s Journal of the International Neuropsychological Society.

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Dianne Partie Lange