Long-Term Marijuana Use Associated with Worse Verbal Memory in Middle Age

marijuana plant

Marijuana use over time was associated with remembering fewer words from a list but it did not appear to affect other areas of cognitive function in a study of men and women followed up over 25 years, according to an article published online by JAMA Internal Medicine.

Marijuana use is common among adolescents and young adults. It remains unclear whether there are long-term effects from low-intensity or occasional marijuana use earlier in life and whether the magnitude and persistence of impairment depends on the duration of marijuana use or the age of exposure.

The Coronary Artery Risk Development in Young Adults (CARDIA) study includes 25 years of repeated measures of marijuana exposure starting in early adulthood. In year 25, CARDIA measured cognitive performance using standardized tests of verbal memory, processing speed and executive function. 

Reto Auer, MD, MAS, a graduate of the Training in Clinical Research (TCIR) program and now at the University of Lausanne, Switzerland, is first author on the paper, and Mark Pletcher, MD, MPH, professor in DEB is senior author.  Other DEB contributors include Eric Vittinghoff, PhD, MPH, Maria Glymour, ScD, MS and affiliated faculty member Kristine Yaffe, MD.

You can read the study online