Genetic and Environmental Influences on Trauma Exposure and Posttraumatic Stress Disorder Symptoms: A Twin Study (original) (raw)

Do genes influence exposure to trauma? A twin study of combat

American Journal of Medical Genetics, 1993

Data from 4,029 male-male twin pairs who served in the United States military during the Vietnam era (1965–1975) were used to examine genetic and non-genetic factors that influence wartime exposure to traumatic events. Specific events examined were volunteering for service in Vietnam, actual service in Southeast Asia, a composite index of 18 combat experiences, and information from military records about being awarded combat decorations. Correlations within monozygotic (MZ) and dizygotic (DZ) twin pairs for volunteering for service in Vietnam were 0.40 and 0.22, respectively. For actually serving in Southeast Asia, the MZ correlation was 0.41 and the DZ correlation was 0.24. Analysis of twin pairs in which both siblings served in Southeast Asia (n = 820) demonstrated a correlation for self-reported combat experiences within MZ and DZ pairs of 0.53 and 0.30, respectively. Heritability estimates ranged from 35 to 47%. The family environment did not have a significant effect on any of the variables. Analyses of data from military records regarding being awarded a combat decoration provided very similar results to those found for self-reported combat experiences. © 1993 Wiley-Liss, Inc.

Genetic Contributions to Posttraumatic Stress Disorder

2013

There are few topics in the field of traumatic stress studies that clinicians approach more ambivalently than considerations of genetic factors associated with vulnerability or resistance to traumatization. Historically, individuals suffering from combat-related posttraumatic stress disorder (PTSD) received diagnoses including "soldier's heart" or "neurocirculatory asthenia," and were frequently viewed as possessing characteristics that cast them in a disparaging light, such as "constitutional inferiority" and "lack of virility" (Campbell, 1918; see Krystal et al., 1989). Early studies implicated race as an important factor influencing the vulnerability to psychological stress (cf. Dunn, 1942). However, these studies attempted to use flawed clinical data to support widely held societal prejudices against minority groups, similar to early misguided efforts to characterize the inheritance of intelligence (Gould, 1981 ). Similarly, German aut...

The Role of Social Environment and Gene Interactions on Development of Posttraumatic Stress Disorder

2016

Among 590 hurricane-exposed Floridians, the serotonin transporter genotype, 5-HTTLPR, was associated with decreased risk of posttraumatic stress disorder (PTSD) in county-level low-risk environments (low crime/unemployment rates) but increased PTSD in county-level high-risk environments (Koenen et al., 2009). These results suggest genetic vulnerability to PTSD may be affected by environmental settings. The current study replicates Koenen’s by examining if genetic vulnerability is affected by recovery environment among 55 female sexual assault survivors. It was hypothesized that the s’ allele of the 5-HTTLPR polymorphism would evidence fewer PTSD symptoms among those in low-risk environments, and, conversely, increased PTSD symptoms among those in highrisk environments. The D2 dopamine receptor gene DRD2 (rs6277 and rs6279) and the FKBP5 (rs3800373 and rs1360780) gene regions were also explored. Hierarchical regression analyses revealed that while none of the five gene regions yielde...