In a new study published by the American Journal of Psychiatry, researchers tested memory and reasoning in 3,800 high school students, ages 13 to 17.
They found marijuana affected their long-term cognitive abilities more than alcohol.
Researchers say what's even more concerning is when students stopped smoking pot, their memory didn't get better.
Scientists say they need to do more research to find out how and why the brain is affected by early marijuana use.
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