Marijuana smokers more prone to false memories

MRI scans showed weed smokers had lower levels of activation in portions of the brain linked to memory and recall.
By Brooks Hays  |  April 21, 2015 at 2:16 PM
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BARCELONA, Spain, April 21 (UPI) -- Stoners don't make for good eye witnesses. According to new research, their accounts are more likely to be plagued by false memories.

Previous research has shown that long-term cannabis use can impair a person's short- and long-term memory. But the latest study -- published in the Journal of Molecular Biology -- proves pot smokers are more likely to supplement their faulty memory with false ones. Researchers proved as much using word games to test smokers' memory skills.

Study participants were first shown lists of words and asked to memorize them. After a few minutes, the participants were shown the original words, as well as new words (some semantically related, others not), and asked to identify which belonged to the original list.

Chronic cannabis users were more likely than their pot-free peers to falsely identify semantically related new words as belonging to the original list.

Researchers also coupled their semantic word quiz with real-time brain scans. The imaging showed weed smokers had lower levels of activation in portions of the brain linked to memory and recall.

"These findings indicate that cannabis users have an increased susceptibility to memory distortions even when abstinent and drug-free, suggesting a long-lasting compromise of memory and cognitive control mechanisms involved in reality monitoring," researchers wrote in their newly published paper.

A study published earlier this year by researchers at Northwestern Medicine showed adults who had smoked weed regularly in their teens were more likely to have abnormal hippocampus and exhibit memory problems.

"The memory processes that appear to be affected by cannabis are ones that we use every day to solve common problems and to sustain our relationships with friends and family," said Dr. John Csernansky, a behavioral scientist at Northwestern.

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