Cannabis damages teen brains more than alcohol, study finds

According to a study of almost 4,000 teenagers, the long-term impact on comprehension from cannabis use depends on what age people begin to smoke it. Researchers at the University of Montreal published research in the American Journal of Psychiatry showing how smoking marijuana affects the development of the brain over time. They found that sustained cannabis users were much more likely to have adverse impacts on their thinking ability.

The research team tracked 3,826 Canadian teenagers for four years, monitoring the extent their alcohol and drug use while also giving them a series of tests for memory and perception. Their report stated that teenagers who smoked marijuana consistently and with increased frequency showed a decrease in cognitive functions, including inhibition, perceptual reasoning, recall memory, and working memory.

The study showed that both alcohol and marijuana had an impact on the way teen’s brains functioned, but the senior author, Dr Patricia Conrod, said that increased marijuana use, but not increased alcohol consumption, resulted in both concurrent and lagged adverse impacts on cognition.

The research team assessed the teenagers by using several memory tests. The teens tried to learn and repeat a pattern of stimuli and solve a series of puzzles that increased in difficulty. Dr Conrod said her team was surprised that smoking marijuana had a more adverse effect than drinking alcohol and at how long the effects persisted. She added that even if a teenager reduced the frequency of marijuana use, the researchers could still observe the adverse effects of the prior year’s use.