Much of what we know about this topic comes from mass trauma like military combat or natural disasters where the cause is known and there are many sufferers, often adults. These findings are informative, but of only limited help in the kind of cases I saw where the events happened in childhood, usually involved other figures, and were not witnessed. Another complication was that, for a time, childhood trauma was a fad diagnosis attracting suggestable patients and therapists alike in an almost circus-like atmosphere – so the diagnosis was often suspect. Fortunately, that era has mostly passed.
I bring it up here because one of the things people focus on is resiliency as an explanation for why some people develop PTSD after traumatic exposure and others don’t – resiliency being a hypothesized quality that protects people from developing PTSD. I’ve balked at the term as it seems like a value judgement – close to strong versus weak. Like the traumatized person was somehow defective, or that the protective resiliency could be taught. I’ve thought of it as a tautology – an objective observation being turned into some hypothetical inner quality. Things like courage, cowardice,or confidence are other examples. I actually thought the patients I saw were some pretty resilient people who had dealt with harsh or unfortunate reality, and survived [I obviously don't like the notion of resiliency in understanding trauma].
You wouldn’t know it from what I’ve just said, but my topic is preventive medicine and the current focus of psychiatry on preventive strategies. The centerpiece of preventive medicine is early detection and intervention – identifying patients before they get sick, or at least very early in the illness. In psychiatry, we’d love to have biomarkers for things like Schizophrenia so we could try to learn to head off the development of frank psychosis. That was the logic behind the idea of the Attenuated Psychosis Syndrome proposal in the DSM-5 – one of the diagnoses that didn’t pan out.
In the Aftermath of Tragedy: Medical and Psychiatric Consequences
by Charles B. Nemeroff and Pascal J. Goldschmidt-Clermont
Academic Psychiatry. 2011 35:4-7.
Epidemiological studies indicate that about 70% of people will experience a traumatic event in their lifetime, but not all of these individuals will develop PTSD. Identifying which trauma victims will develop PTSD is the agreed upon “holy grail” for the PTSD research field. Clearly, a clinically useful metric using a combination of biological, epidemiological, and psychological variables to predict who, at the time of trauma, will develop PTSD will revolutionize the treatment of this common and severe psychiatric disorder. The savings in terms of human suffering, medical and psychiatric comorbidity, reduction in suicide risk, disability, and loss of life as well as economic gains in terms of reduced health care utilization and increased work productivity are virtually incalculable. Considering the almost universal exposure to traumatic events and the vast public health problem that PTSD represents worldwide, the global impact in civilian and military populations will be substantial.
Functional genomics, transcriptomics, and the related fields of proteomics and epigenetics allow high throughput hypothesis generators. These approaches have proven successful in identifying disease biomarkers in several common complex disorders including Alzheimer’s disease, cancer, and diabetes. The concern that the use of blood elements instead of brain tissue does not provide valid data in gene expression appears to be unwarranted. We need to accelerate discoveries for the prevention, diagnosis, and treatment of PTSD. Applying genomics, transcriptomics, epigenetics, and proteomics to elucidate biological predicators of PTSD is an active avenue of investigation. Approximately 30% to 40% of the risk to develop PTSD is heritable and our group has identified some of the most promising candidate genes that mediate vulnerability to PTSD. Much of what we have learned concerning the mammalian response to trauma is derived from basic science discoveries, and these findings, in part, provide the scientific rationale for identifying predictors of PTSD [e.g., inflammatory markers and neuroendocrine alterations]. PTSD is a major global health problem and success will result in a clear and immediate global health impact.The use of such genomic, transcriptomic, epigenetic, proteomic, structural and functional brain imaging, inflammation, and neuroendocrine measures taken together with behavioral and psychological measures will likely achieve the much needed goal of predicting which trauma victims will develop syndromal PTSD and, moreover, will likely help identify predictors of response to the effective treatments of PTSD, both psychotherapeutic and psychopharmacological. In the future, such tools can be brought to bear to help manage the psychiatric sequelae of natural disasters similar to the Haiti earthquake. Immediate intervention for medical-surgical and psychiatric consequences of trauma will surely reduce the resultant morbidity and mortality associated with such events….
A twin study of genetic and environmental contributions to liability for posttraumatic stress symptoms.
by True WR, Rice J, Eisen SA, Heath AC, Goldberg J, Lyons MJ, and Nowak J.
Archives of General Psychiatry. 1993 50:257-264.
We studied 4042 Vietnam era veteran monozygotic and dizygotic male twin pairs to determine the effects of heredity, shared environment, and unique environment on the liability for 15 self-reported posttraumatic stress disorder symptoms included in the symptom categories of reexperiencing the trauma, avoidance of stimuli related to the trauma, and increased arousal. Quantitative genetic analysis reveals that inheritance has a substantial influence on liability for all symptoms. Symptoms in the reexperiencing cluster and one symptom in the avoidance and numbing cluster are strongly associated with combat exposure, and monozygotic pairs are more highly concordant for combat exposure than dizygotic pairs. By fitting a bivariate genetic model, we show that there are significant genetic influences on symptom liability, even after adjusting for differences in combat exposure; genetic factors account for 13% to 30% of the variance in liability for symptoms in the reexperiencing cluster, 30% to 34% for symptoms in the avoidance cluster, and 28% to 32% for symptoms in the arousal cluster. There is no evidence that shared environment contributes to the development of posttraumaticstress disorder symptoms.
Genetic and environmental influences on trauma exposure and posttraumatic stress disorder symptoms: a twin study.
by Stein MB, Jang KL, Taylor S, Vernon PA, and Livesley WJ.
American Journal of Psychiatry. 2002 159:1675-1681.
OBJECTIVE: Posttraumatic stress disorder [PTSD] develops in only a subset of persons exposed to traumatic stress, suggesting the existence of stressor and individual differences that influence risk. In this study the authors examined the heritability of trauma exposure and PTSD symptoms in male and female twin pairs of nonveteran volunteers.METHOD: Scores on a traumatic events inventory and a DSM-IV PTSD symptom inventory were examined in 222 monozygotic and 184 dizygotic twin pairs. Biometrical model fitting was conducted by using standard statistical methods.RESULTS: Additive genetic, common environmental, and unique environmental effects best explained the variance in exposure to assaultive trauma [e.g., robbery, sexual assault], whereas exposure to nonassaultive trauma [e.g., motor vehicle accident, natural disaster] was best explained by common and unique environmental influences. PTSD symptoms were moderately heritable, and the remaining variance was accounted for by unique environmental experiences. Correlations between genetic effects on assaultive trauma exposure and on PTSD symptoms were high.CONCLUSIONS: Genetic factors can influence the risk of exposure to some forms of trauma, perhaps through individual differences in personality that influence environmental choices. Consistent with symptoms in combat veterans, PTSD symptoms after noncombat trauma are also moderately heritable. Moreover, many of the same genes that influence exposure to assaultive trauma appear to influence susceptibility to PTSD symptoms in their wake.
Heritabilities of symptoms of posttraumatic stress disorder, anxiety, and depression in earthquake exposed Armenian families.
by Goenjian AK, Noble EP, Walling DP, Goenjian HA, Karayan IS, Ritchie T, and Bailey JN.
Psychiatric Genetics. 2008 18:261-266.
OBJECTIVE: To examine the heritabilities of symptoms of posttraumatic stress disorder [PTSD], anxiety, depression, and the shared genetic component of these symptoms among family members exposed to the 1988 Spitak earthquake in Armenia.METHODS: Two hundred members of 12 multigenerational families exposed to the Spitak earthquake were studied using a battery that assessed earthquake exposure and symptoms of PTSD, anxiety, and depression. Heritabilities of these phenotypes were determined using variance component analyses and shared genetic vulnerabilities between these phenotypes were determined using bivariate analyses.RESULTS: Heritabilities were as follows: PTSD symptoms 41% [P<0.001], anxiety symptoms 61% [P<0.001], and depressive symptoms 66% [P<0.001]. The genetic correlation [rhog>0] of PTSD symptoms with anxiety symptoms was 0.75 [P<0.001] and with depressive symptoms it was 0.71 [P<0.001]. The genetic correlation of anxiety with depressive symptoms was 0.54 [P<0.001].CONCLUSION: The heritabilities found in this multigenerational family study indicate that the genetic make-up of some individuals renders them substantially more vulnerable than others to develop symptoms of PTSD, anxiety, and depression. A large proportion of the genetic liability for PTSD, anxiety, and depression are shared. The findings offer promise for identifying susceptibility genes for these phenotypes.