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Post-Traumatic Stress Disorder |
Overcoming Anxiety (Home) > Post-Traumatic Stress Disorder > Predictors and Risk Factors Predictors and Risk Factors: Behavioral Survey, Stroke and CausesGenetic FactorsThere are indications that genetic factors may contribute to the susceptibility to PTSD symptomatology. Comparison of monozygotic (MZ) with dizygotic (DZ) twins in order to determine the effects of heredity, shared environment and unique environment demonstrated that heredity indeed contributes substantially to the susceptibility to nearly all symptoms, taking into account differences in concordance for combat exposure between MZ and DZ twins. The level of combat exposure itself predicted mainly the re-experiencing symptoms and the avoided activities, not the numbing. Interestingly, shared family-life experiences did not contribute to the susceptibility to PTSD symptoms . In an earlier study, a specific effect of the level of combat exposure on the occurrence and intensity of the same PTSD symptoms had been shown, demonstrating a dose–response relationship within a genetically homogeneous population on a paired observations basis . Also in other studies, a dose–response relationship of duration and intensity of combat exposure was demonstrated . Polymorphism of the dopamine D2-receptor gene, the occurrence of the D2A1 allele, has been found associated with PTSD although PTSD can certainly not be thought of as a single gene disorder . It is inferred that the D2A1 allele is in linkage desequilibrium with a mutation of a non-transcribed portion of the DRD2 gene causing receptor dysfunction. The statistical significance was very high and highest for the hyperarousal (‘‘D’’) criterion. Increased prevalence of the same allele had previously been found in attention-deficit/hyperactivity disorder (ADHD), Gilles de la Tourette’s syndrome, conduct disorder and substance-related disorder, e.g. alcoholism. This suggests that genetically determined differences in the dopaminergic system may have an important role in pathological development of human stress responses and that this transcends DSM diagnostic groups as a pathogenic dimension at the molecular level, the biological floorplan. The existence and influence of this type of susceptibility traits might also explain why only a limited number of exposed individuals develop a post-traumatic disorder. In the case of ADHD, specifically, it could clarify the confusion about ADHD as a post-traumatic syndrome versus independent familial predisposition for ADHD . At the same time this implies that for the development of a psychiatric disorder that can be classified as one of the above, additional factors, genetic, developmental or environmental, are needed to produce them. Psychological Factors and InteractionsProspectively, neuroticism and extroversion were factors that could predict the exposure to traumatic events per se, but early misconduct or a family history of a psychiatric disorder could not do so and educational level was only marginally significant in this study of exposure. With respect to development of PTSD, cognitive variables may well affect the ability to cope with trauma, thereby influencing whether a person develops the chronic condition . Linked to this, education was indeed found to influence the development of PTSD. A prospective study in World War II veterans provides an indication of the specificity of PTSD symptoms. Combat exposure and number of physiological symptoms during combat stress predicted PTSD symptoms at one and at 41 years after the war. On the other hand, psychosocial vulnerability during adolescence and at age 65, and the display of physiological symptoms during civil life stress predicted trait neuroticism at age 65. Thus, combat exposure proved more specific for the development of PTSD, and premorbid vulnerability more specific for psychoneurotic pathology. Interestingly but not unexpected, characteristics of the individual and his or her behaviour also influence the likelihood of exposure to traumatic events. Correlation for volunteering for military service in Vietnam, for actual service in South-East Asia, for self-reported combat experiences, and for being awarded combat decorations were higher within MZ than in DZ twins . Gender is another factor that influences susceptibility to traumatic experiences in developing PTSD. More women than men develop PTSD after exposure to major trauma and duration of symptoms in women is longer . In veterans this held true after adjustment for pre-combat physical or sexual abuse and pre-combat psychiatric history . However, such abuse itself seemed to promote the development of PTSD after combat exposure. Early Signs as PredictorsA much better predictor of the development of PTSD has been found in peri- traumatic dissociation, even better and stronger than depression, anxiety and intrusive symptoms . This might help clinicians to dentify subjects at risk for development of the disorder. Heart rate in the peri-traumatic phase, i.e. in theemergency room after traffic accidents, etc., was also positively correlated to the development of PTSD . In an extension of the study, again peri-traumatic dissociation and heart rate predicted the development of PTSD and were associated with more intrusive symptoms and with exaggerated startle . Comorbid depression occurred in more than 40% at one and four months but was stated to be an independent consequence and to be associated with prior depression. A negative correlation between serum cortisol immediately after traumatisation and the development of PTSD was found in two different settings, namely sexual assault and motor vehicle accidents. These psychophysiological factors raise the issue of pre-traumatic vulnerability in the development of PTSD , which would discard the notion that this disorder is a normal reaction to abnormal events as has been proposed by some experts in the field during the last two decades. The acute stress response, a classification newly introduced in the DSM-IV, has been shown to have internal coherence and can strongly predict the development of PTSD . Although the development of PTSD could indeed be predicted in road traffic accident victims on the basis of the existence and severity of early PTSD-related symptoms one week after the accident, the following three months appeared to be the critical period for the development of the full disorder .
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