title: Posttraumatic stress disorder in war veterans: a discussion of the Neuroevolutionary Time-depth Principle.
abstract: BACKGROUND
  Trauma is a universal phenomenon. Violence is a type of trauma and war is one of the ways in which violence is expressed. The "Neuroevolutionary Time-depth Principle" of innate fears, based on prevalence data, suggests that high rates of posttraumatic stress disorder (PTSD) after combat exposure can be due to the fact that this fear-stress response appeared as a reaction to inter-group male-to-male and intra-group killings after the rising of population densities in the Neolithic period.
  
  
  METHODS
  Studies of PTSD prevalence available in MEDLINE, Institute for Scientific Information Databases (Science Citation Index Expanded, Social Sciences Citation Index, and Arts and Humanities Citation Index), EMBASE, and Cochrane Library were identified and reviewed.
  
  
  RESULTS
  Prevalence data of PTSD deeply vary from one country to another, even in groups exposed to similar stressors. Moreover, war is not a uniform and unchanged phenomenon and not all war stressors are similar because some of them are known to lead to PTSD more than others.
  
  
  CONCLUSIONS
  We argue that psychosocial narratives deeply influence our biological response to trauma and violence, shaping the genotypical response to trauma. Great differences in prevalence may be in part due to this fact. We also suggest that personal preconceptions and socio-cultural interests may also be playing a critical role in the theories developed to explain the nature of our response to violence.
  
  
  CONCLUSIONS
  A comprehensive model for war-related PTSD should integrate both genotypical and phenotypical findings.
authors.affiliation: Department of Psychiatry, Vall d'Hebron University Hospital, Paseo Vall d'Hebron, 119-129, 08035, Barcelona, Spain. dbraquehais@yahoo.es
authors.forename: María Dolores
authors.initials: MD
authors.lastname: Braquehais
authors.forename: Leo
authors.initials: L
authors.lastname: Sher
mesh_terms: D000328:Adult; D055826:Afghan Campaign 2001-; D005075:Biological Evolution; D001921:Brain / Q000503:physiopathology; D002648:Child; D003130:Combat Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology / Q000523:psychology*; D015897:Comorbidity; D003431:Cross-Cultural Comparison; D003430:Cross-Sectional Studies; D019143:Evolution, Molecular; D005239:Fear / Q000523:psychology; D005783:Gender Identity; D005838:Genotype; D006801:Humans; D054542:Iraq War, 2003-2011; D008297:Male; D010641:Phenotype; D011156:Population Density; D055500:Resilience, Psychological; D012945:Social Values; D013313:Stress Disorders, Post-Traumatic / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology / Q000523:psychology*; D023481:Terrorism / Q000523:psychology; D014728:Veterans / Q000523:psychology* / Q000706:statistics & numerical data; D014754:Violence / Q000523:psychology* / Q000706:statistics & numerical data; D014857:Warfare