title: Neurocognitive correlates of white matter quality in adolescent substance users.
abstract: BACKGROUND
  Progressive myelination during adolescence implicates an increased vulnerability to neurotoxic substances and enduring neurocognitive consequences. This study examined the cognitive manifestations of altered white matter microstructure in chronic marijuana and alcohol-using (MJ+ALC) adolescents.
  
  
  METHODS
  Thirty-six MJ+ALC adolescents (ages 16-19) and 36 demographically similar controls were evaluated with diffusion tensor imaging (Bava et al., 2009) and neurocognitive tests. Regions of group difference in fractional anisotropy (FA) and mean diffusivity (MD) were analyzed in relation to cognitive performance.
  
  
  RESULTS
  In users, lower FA in temporal areas related to poorer performance on attention, working memory, and speeded processing tasks. Among regions where users had higher FA than controls, occipital FA was positively associated with working memory and complex visuomotor sequencing, whereas FA in anterior regions was negatively associated with verbal memory performance.
  
  
  CONCLUSIONS
  Findings suggest differential influences of white matter development on cognition in MJ+ALC using adolescents than in non-using peers. Neuroadaptation may reflect additive and subtractive responses to substance use that are complicated by competing maturational processes.
authors.affiliation: University of California, Department of Psychiatry, 9500 Gilman Drive, San Diego, CA 92093-0603, United States.
authors.forename: Sunita
authors.initials: S
authors.lastname: Bava
authors.forename: Joanna
authors.initials: J
authors.lastname: Jacobus
authors.forename: Omar
authors.initials: O
authors.lastname: Mahmood
authors.forename: Tony T
authors.initials: TT
authors.lastname: Yang
authors.forename: Susan F
authors.initials: SF
authors.lastname: Tapert
mesh_terms: D000293:Adolescent; D041923:Adolescent Development / Q000187:drug effects; D000437:Alcoholism / Q000150:complications / Q000473:pathology* / Q000523:psychology; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000187:drug effects / Q000254:growth & development / Q000473:pathology*; D003072:Cognition Disorders / Q000209:etiology / Q000473:pathology* / Q000523:psychology; D015331:Cohort Studies; D055030:Drug Users / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000150:complications / Q000473:pathology* / Q000523:psychology; D009413:Nerve Fibers, Myelinated / Q000187:drug effects / Q000473:pathology*; D009483:Neuropsychological Tests; D012016:Reference Values; D055815:Young Adult