Some have touted potential health benefits from smoking marijuana for many years, but now a new study suggests that pot may actually have a negative impact on health. A study published in the Journal of the American Medical Association’s Internal Medicine division section suggests that smoking pot for years could impact verbal memory, making it more difficult to remember some words while speaking.

Marijuana May Negatively Impact Verbal Memory

CARDIA looked at marijuana use after 25 years

According to an article from Livescience, researchers said that about half of marijuana smokers experienced a reduction in their ability to remember words. They said for every five years users had smoked pot, half of them recalled one word fewer out of a 15-word list. However, researchers did not see any negative impacts on other cognitive function measures like the abilities to plan or focus (executive functions) or users’ processing speed, said the study.

The Coronary Artery Risk Development in Young Adults study went on for many years and included results from more than 5,000 enrollees who were aged 18 to 30. Participants reported on their follow-up visits whether or not they had smoked marijuana in the month before. After 25 years, researchers then gave them some cognitive tests to examine processing speed, executive functions and verbal memory. They only did the tests after the 25-year mark.

Verbal memory worsens with more years of marijuana smoking

The researchers associated long-term use of marijuana worth worse performance in all three of their tests after adjusting for a number of other factors like depression and using other drugs or alcohol. However, the only statistically significant link out of the three was the one associating a negative impact on verbal memory with long-term marijuana use. As a result, they think the links between pot and the other two cognitive functions might have happened only because of chance.

They also found independently that that the more marijuana someone smoked over a longer period of time, the worse their verbal memory got in middle age. They’re not exactly sure just how exposure to the drug impacts verbal memory, although one suggestion they offer is that tetrahydrocannabinol, better known as THC, which causes most of the psychological effects of the drug, could impact how the hippocampus processes information.

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