4,000 Pairs of Twins Were Studied, 1 Smoked Weed and 1 Didn’t – Cannabis Use Did Not Cause Any Negative Mental Health Outcomes

“This study suggests that lifetime exposure to cannabis has few persistent effects on mental health and other psychosocial outcomes,” said the researchers. “We did not identify within-pair differences in cognitive ability… Cannabis consumption did not predict within-pair differences in psychoticism,” they added. In effect, lifetime consumption of weed didn’t lead to negative mental health outcomes among the sample.