title: Substance abuse risk in emerging adults associated with smaller frontal gray matter volumes and higher externalizing behaviors.
abstract: BACKGROUND
  During emerging adulthood, alcohol and substance use peak. Previous research has suggested that prefrontal and subcortical brain volumes may relate to risk for development of substance abuse. Epidemiological studies indicate that early initiation of alcohol or drug use significantly increases the likelihood of later substance use disorder diagnoses. We hypothesized that frontal regions would be smaller in young adults with early substance use and related problems (early-risk, ER), compared with a control group without early use/problems (C). We further hypothesized that these volumes would be associated with more externalizing behaviors, an additional robust predictor of substance abuse.
  
  
  METHODS
  One hundred and six subjects, ages 18-23, underwent high-resolution anatomical magnetic resonance image scanning. Individuals were categorized as C (n=64) or ER (n=42) using a composite-score of early alcohol/drug use and problems based on prospectively collected assessments; externalizing behaviors were also previously assessed during adolescence. Neuroanatomical volumes were compared between groups and correlated with behavioral measures.
  
  
  RESULTS
  ER subjects exhibited more externalizing behaviors than their control counterparts. Total left frontal cortex and left superior frontal cortex volumes were significantly smaller in the ER group, controlling for family history of alcoholism and current substance use. Total gray matter volumes were negatively associated with substance risk score. Further, externalizing behavior score was negatively correlated with both left superior cortical and left total cortical volumes.
  
  
  CONCLUSIONS
  These findings suggest that smaller frontal cortical volumes, specifically the left superior frontal cortex, represent an underlying risk factor for substance abuse in emerging adults.
authors: Department of Psychiatry, The University of Michigan, Ann Arbor, MI, United States; Addiction Research Center, The University of Michigan, Ann Arbor, MI, United States; Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, United States. Electronic address: barbara.weiland@colorado.edu.
authors: Barbara J
authors: BJ
authors: Weiland
authors: Department of Psychiatry, The University of Michigan, Ann Arbor, MI, United States; Addiction Research Center, The University of Michigan, Ann Arbor, MI, United States.
authors: Steven T
authors: ST
authors: Korycinski
authors: Department of Psychiatry, The University of Michigan, Ann Arbor, MI, United States; Addiction Research Center, The University of Michigan, Ann Arbor, MI, United States.
authors: Mary
authors: M
authors: Soules
authors: Department of Psychiatry, The University of Michigan, Ann Arbor, MI, United States; Molecular and Behavioral Neuroscience Institute, The University of Michigan, Ann Arbor, MI, United States.
authors: Jon-Kar
authors: JK
authors: Zubieta
authors: Department of Psychiatry, The University of Michigan, Ann Arbor, MI, United States; Addiction Research Center, The University of Michigan, Ann Arbor, MI, United States.
authors: Robert A
authors: RA
authors: Zucker
authors: Department of Psychiatry, The University of Michigan, Ann Arbor, MI, United States; Addiction Research Center, The University of Michigan, Ann Arbor, MI, United States.
authors: Mary M
authors: MM
authors: Heitzeg
mesh_terms: D000293:Adolescent; D000367:Age Factors; D005260:Female; D005625:Frontal Lobe / Q000473:pathology*; D006801:Humans; D008297:Male; D009929:Organ Size; D011446:Prospective Studies; D012307:Risk Factors; D012309:Risk-Taking; D019966:Substance-Related Disorders / Q000175:diagnosis* / Q000523:psychology*; D055815:Young Adult
keywords: Emerging adult; Externalizing behavior; Middle frontal cortex; Substance risk; Superior frontal cortex