title: Association Between Lifetime Marijuana Use and Cognitive Function in Middle Age: The Coronary Artery Risk Development in Young Adults (CARDIA) Study.
abstract: OBJECTIVE
  Marijuana use is increasingly common in the United States. It is unclear whether it has long-term effects on memory and other domains of cognitive function.
  
  
  OBJECTIVE
  To study the association between cumulative lifetime exposure to marijuana use and cognitive performance in middle age.
  
  
  METHODS
  We used data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, a cohort of 5115 black and white men and women aged 18 to 30 years at baseline from March 25, 1985, to June 7, 1986 (year 0), and followed up over 25 years from June 7, 1986, to August 31, 2011, to estimate cumulative years of exposure to marijuana (1 year = 365 days of marijuana use) using repeated measures and to assess associations with cognitive function at year 25. Linear regression was used to adjust for demographic factors, cardiovascular risk factors, tobacco smoking, use of alcohol and illicit drugs, physical activity, depression, and results of the mirror star tracing test (a measure of cognitive function) at year 2. Data analysis was conducted from June 7, 1986, to August 31, 2011.
  
  
  METHODS
  Three domains of cognitive function were assessed at year 25 using the Rey Auditory Verbal Learning Test (verbal memory), the Digit Symbol Substitution Test (processing speed), and the Stroop Interference Test (executive function).
  
  
  RESULTS
  Among 3385 participants with cognitive function measurements at the year 25 visit, 2852 (84.3%) reported past marijuana use, but only 392 (11.6%) continued to use marijuana into middle age. Current use of marijuana was associated with worse verbal memory and processing speed; cumulative lifetime exposure was associated with worse performance in all 3 domains of cognitive function. After excluding current users and adjusting for potential confounders, cumulative lifetime exposure to marijuana remained significantly associated with worse verbal memory. For each 5 years of past exposure, verbal memory was 0.13 standardized units lower (95% CI, -0.24 to -0.02; P = .02), corresponding to a mean of 1 of 2 participants remembering 1 word fewer from a list of 15 words for every 5 years of use. After adjustment, we found no associations with lower executive function (-0.03 [95% CI, -0.12 to 0.07]; P = .56) or processing speed (-0.04 [95% CI, -0.16 to 0.08]; P = .51).
  
  
  CONCLUSIONS
  Past exposure to marijuana is associated with worse verbal memory but does not appear to affect other domains of cognitive function.
authors.affiliation: Department of Epidemiology and Biostatistics, University of California-San Francisco2Department of Ambulatory Care and Community Medicine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Reto
authors.initials: R
authors.lastname: Auer
authors.affiliation: Department of Epidemiology and Biostatistics, University of California-San Francisco.
authors.forename: Eric
authors.initials: E
authors.lastname: Vittinghoff
authors.affiliation: Department of Epidemiology and Biostatistics, University of California-San Francisco3Department of Psychiatry and Neurology, University of California-San Francisco.
authors.forename: Kristine
authors.initials: K
authors.lastname: Yaffe
authors.affiliation: Department of Ambulatory Care and Community Medicine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Künzi
authors.affiliation: Center for Surgical Medical and Acute Care Research, Birmingham Veterans Affairs Medical Center, Birmingham, Alabama5Department of Medicine, University of Alabama at Birmingham School of Medicine.
authors.forename: Stefan G
authors.initials: SG
authors.lastname: Kertesz
authors.affiliation: Department of Internal Medicine, University of Michigan Medical School, Ann Arbor7Veterans Affairs Center for Clinical Management Research, Ann Arbor, Michigan8Institute for Healthcare Policy and Innovation, University of Michigan, Ann Arbor9Department of.
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Levine
authors.affiliation: Department of Psychiatry, University of Geneva, Geneva, Switzerland.
authors.forename: Emiliano
authors.initials: E
authors.lastname: Albanese
authors.affiliation: Kaiser Permanente Division of Research, Oakland, California.
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Whitmer
authors.affiliation: Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis.
authors.forename: David R
authors.initials: DR
authors.lastname: Jacobs
authors.affiliation: Kaiser Permanente Division of Research, Oakland, California.
authors.forename: Stephen
authors.initials: S
authors.lastname: Sidney
authors.affiliation: Department of Epidemiology and Biostatistics, University of California-San Francisco.
authors.forename: M Maria
authors.initials: MM
authors.lastname: Glymour
authors.affiliation: Department of Epidemiology and Biostatistics, University of California-San Francisco.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Pletcher
mesh_terms: D000328:Adult; D002188:Cannabis / Q000009:adverse effects*; D003071:Cognition; D003324:Coronary Artery Disease / Q000453:epidemiology / Q000209:etiology*; D055030:Drug Users / Q000523:psychology* / Q000706:statistics & numerical data*; D056344:Executive Function; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008568:Memory; D008875:Middle Aged; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D014706:Verbal Learning; D055815:Young Adult
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