Study Indicates Pot Really Can Lower Your IQ

This is your brain on pot: A new study has found that regular marijuana use is linked to both lower IQ scores and impaired decision making skills.

It’s All in Your Mind

The findings from the University of California Davis Centre for Neuroscience compared 50 regular marijuana users to a control group of non-smokers. Researchers found that the IQ of marijuana users was about five points lower than that of non-marijuana users. Even more compelling, the gap was much more significant in those who started smoking at a younger age.

With pot smokers experiencing deficits in decision-making brain volume, neurological compensations must be made. In order to balance things within the brain, smokers require increased neural connectivity. Unfortunately, that’s not something the human brain can sustain over time.

“The results suggest increases in connectivity, both structural and functional, that may be compensating for gray matter losses,” said study co-author Sina Aslan, a faculty member at The University of Texas at Dallas. “Eventually, however, the structural connectivity or ‘wiring’ of the brain starts degrading with prolonged marijuana use.”

Supporting Data

Other recent studies have also confirmed that marijuana has long-term negative consequences on the brain, particularly when used during adolescence.

A project released last December in the journal Schizophrenia Bulletin found that those who were heavy pot users in adolescence had permanent damage in the brain’s sub-cortical regions, which are primitive structures that are part of memory and reasoning circuits. Heavy pot users also fared worse on memory tests that non-users and non-using schizophrenics.

“We see that adolescents are at a very vulnerable stage neuro-developmentally,” said research leader Matthew Smith, of the Northwestern University Feinberg School of Medicine in Chicago. “And if you throw stuff into the brain that’s not supposed to be there, there are long-term implications for their development.”

Looking to the Future

Although marijuana use among smokers between the ages of 12 and 17 dropped from 12 percent in November 2002 to 9.5 percent in 2003, millions of pre-teens and teenagers are still using the drug. These studies show that what many view as “harmless” recreational marijuana use could have permanent cognitive implications for adulthood and beyond.

Learn more about the signs and symptoms of marijuana abuse.

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