Long Term Pot Use Linked to Lost Word Recall
Some studies provide breakthrough information, while others confirm what some may have already suspected.
Researchers in Switzerland set out to study the link between cumulative lifetime marijuana use and cognitive performance in middle age. It may come as no surprise that they found links between prolonged pot use and declining verbal memory.
The researchers used data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, which contains 25 years of marijuana exposure measurements, beginning in early adulthood. In the final year, the study measured cognitive performance through standardized tests of verbal memory, processing speed and executive function.
In total, 3,499 participants were assessed at the 25-year visit, and 3,385 had cognitive function data. Of these, 84.3 percent reported past marijuana use and 11.6 percent reported continuous marijuana use into middle age.
The study team found that past marijuana exposure was linked with worse verbal memory. However, it did not appear to affect other areas of cognitive function. In detail, for every 5 years of past exposure, verbal memory was 0.13 standardized units lower, which the researchers say corresponds to an average of 1 of 2 participants remembering one word fewer from a list of 15 words.
Marijuana use in the U.S. is quite common among adolescents and young adults. Data from 2012 revealed that 37 percent of 12th-graders had used marijuana in the last year, 23 percent used it within the last 30 days and 6.5 percent used it daily.