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Invited Commentary
March 2016

Long-term Marijuana Use and Cognitive Impairment in Middle Age

Author Affiliations
  • 1Centre for Youth Substance Abuse Research, The University of Queensland, Queensland, Australia
  • 2National Addiction Centre, Kings College London, United Kingdom

Copyright 2016 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.

JAMA Intern Med. 2016;176(3):362-363. doi:10.1001/jamainternmed.2015.7850

During the last 20 years, there have been substantial changes in the legal status and public perception of marijuana in the United States. Decriminalization, medical dispensaries with marijuana for those with a physician’s note, and legalization of marijuana in several states have resulted in increased availability and more relaxed views toward marijuana use. However, to our knowledge, relatively little research has been done on the risks of long-term marijuana use.

In this issue of JAMA Internal Medicine, Auer and colleagues1 report an association between cumulative lifetime marijuana exposure and cognitive performance in a prospective study of 3385 middle-aged adults who were followed up for 25 years. Their findings suggest that those who used marijuana on a long-term daily basis have poorer verbal memory in middle age than do their peers who have not smoked marijuana habitually.