Many states in the U.S. have legalized recreational or medical marijuana. It helps to reduce pain and other symptoms for many people, but it also increases the risk of adverse effects.

A study of middle-age individuals suggests that chronic use of marijuana is tied to worse performance on verbal memory tests.

Dr. Reto Auer of the University of Lausanne, Switzerland, and his colleagues studied nearly 3,500 volunteers who were part of a 25-year U.S. study that measured marijuana exposure and several cognitive abilities, including memory, processing speed, and executive function.

Reporting in JAMA Internal Medicine, the investigators found a significant association between prior years of marijuana use and worse verbal memory scores.

The study did not determine whether marijuana use caused lower verbal memory scores, or whether people with lower scores tended to be the kind of people who engaged in longer-term marijuana use.

Other research has shown that chronic daily users of cannabis do perform worse on other cognitive tasks compared to their peers who do not use marijuana.

Taken together, these findings point to the potential mind health benefits of moderation