title: Common heritable contributions to low-risk trauma, high-risk trauma, posttraumatic stress disorder, and major depression.
abstract: BACKGROUND
  Understanding the relative contributions of genetic and environmental factors to trauma exposure, posttraumatic stress disorder (PTSD), and major depressive disorder (MDD) is critical to developing etiologic models of these conditions and their co-occurrence.
  
  
  OBJECTIVE
  To quantify heritable influences on low-risk trauma, high-risk trauma, PTSD, and MDD and to estimate the degree of overlap between genetic and environmental sources of variance in these 4 phenotypes.
  
  
  METHODS
  Adult twins and their siblings were ascertained from a large population-based sample of female and male twin pairs on the basis of screening items for childhood sexual abuse and physical abuse obtained in a previous assessment of this cohort.
  
  
  METHODS
  Structured psychiatric telephone interviews.
  
  
  METHODS
  Total sample size of 2591: 996 female and 536 male twins; 625 female and 434 male nontwin siblings.
  
  
  METHODS
  Lifetime low- and high-risk trauma exposure, PTSD, and MDD.
  
  
  RESULTS
  In the best-fitting genetic model, 47% of the variance in low-risk trauma exposure and 60% of the variance in high-risk trauma exposure was attributable to additive genetic factors. Heritable influences accounted for 46% of the variance in PTSD and 27% of the variance in MDD. An extremely high degree of genetic overlap was observed between high-risk trauma exposure and both PTSD (r = 0.89; 95% CI, 0.78-0.99) and MDD (r = 0.89; 95% CI, 0.77-0.98). Complete correlation of genetic factors contributing to PTSD and to MDD (r = 1.00) was observed.
  
  
  CONCLUSIONS
  The evidence suggests that almost all the heritable influences on high-risk trauma exposure, PTSD, and MDD, can be traced to the same sources; that is, genetic risk is not disorder specific. Individuals with a positive family history of either PTSD or MDD are at elevated risk for both disorders and should be closely monitored after a traumatic experience for symptoms of PTSD and MDD.
authors.affiliation: Department of Psychiatry, Yale School of Medicine, VA Connecticut Healthcare System, USA. carolyn.sartor@yale.edu
authors.forename: Carolyn E
authors.initials: CE
authors.lastname: Sartor
authors.forename: Julia D
authors.initials: JD
authors.lastname: Grant
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lynskey
authors.forename: Vivia V
authors.initials: VV
authors.lastname: McCutcheon
authors.forename: Mary
authors.initials: M
authors.lastname: Waldron
authors.forename: Dixie J
authors.initials: DJ
authors.lastname: Statham
authors.forename: Kathleen K
authors.initials: KK
authors.lastname: Bucholz
authors.forename: Pamela A F
authors.initials: PA
authors.lastname: Madden
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Heath
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Martin
authors.forename: Elliot C
authors.initials: EC
authors.lastname: Nelson
mesh_terms: D000328:Adult; D054523:Adult Survivors of Child Abuse / Q000523:psychology / Q000706:statistics & numerical data; D002648:Child; D002649:Child Abuse / Q000523:psychology; D002650:Child Abuse, Sexual / Q000523:psychology; D015897:Comorbidity; D003865:Major Depressive Disorder / Q000453:epidemiology / Q000209:etiology / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D007406:Interview, Psychological; D008297:Male; D015995:Prevalence; D012737:Sex Factors; D013313:Stress Disorders, Post-Traumatic / Q000453:epidemiology / Q000209:etiology / Q000235:genetics*; D014427:Twins / Q000523:psychology