As More States Consider Legalizing, Questions About Pot And The Brain

NPR:

Five states are voting this fall on whether marijuana should be legal, like alcohol, for recreational use. That has sparked questions about what we know — and don’t know — about marijuana’s effect on the brain.

Research is scarce. The U.S. Drug Enforcement Agency classifies marijuana as a Schedule I drug. That classification puts up barriers to conducting research on it, including a cumbersome DEA approval application and a requirement that scientists procure very specific marijuana plants.

One long-term study in New Zealand compared the IQs of people at age 13 and then through adolescence and adulthood to age 38. Those who used pot heavily from adolescence onward showed an average 8 percent drop in IQ. People who never smoked, by contrast, showed slightly increased IQ.

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Jackson and Joshua Isen, now an assistant professor of psychology at the University of South Alabama, conducted a study comparing IQ tests of twins age 9 to 12, before either had smoked marijuana, and then seven to 10 years later, after one had started.

Read the whole story: NPR