Posttraumatic stress disorder (PTSD) is a prolonged reaction to an extremely traumatic experience. One of the core symptoms of PTSD is hyper-arousal which can be the result of an elevated activation of the autonomic nervous system. Including psychophysiological assessment methods in PTSD research can point to the neurobiological bases of the disorder. The studies of psychophysiology of PTSD to date have mostly measured reactivity. The aim of the current study was to compare resting state psychophysiology and startle reflexes in PTSD patients and controls in a sample of Croatian combat veterans. We measured heart-rate, respiratory sinus arrhythmia, skin conductance, and eyeblink muscle contraction during an acclimation period and during the presentation of startle stimuli in 45 male PTSD patients and 33 male healthy controls. We found that PTSD patient had elevated baseline heart-rate and decreased respiratory sinus arrhythmia compared to the controls. Furthermore, PTSD patients had impaired habituation to the startle probe, but there was no group difference in initial startle magnitude. There was also no group difference in skin conductance level or skin conductance response. Startle habituation and baseline heart-rate appear to offer the most reliable psychophysiological indices of PTSD. This finding replicates trends in the literature in a new population of PTSD patients.

The study found significant ethnic differences in BDNF val66met polymorphism. The most frequent genotype among Korean participants was "Met/Val" and they had similar distribution of "Met" and "Val" alleles. In contrast, the most frequent genotype among Caucasian participants was "Val/Val" and they had different distribution of "Met" and "Val" alleles. These ethnic differences require matching participants for ethnicity in pharmacogenetic studies and in the studies investigating genetic variations in neuropsychiatric disorders.

Objectives. Psychotic symptoms frequently occur in veterans with combat-related posttraumatic stress disorder (PTSD). Brain-derived neurotrophic factor (BDNF) plays a major role in neurodevelopment, neuro-regeneration, neurotransmission, learning, regulation of mood and stress responses. The Met allele of the functional polymorphism, BDNF Val66Met, is associated with psychotic disorders. This study intended to assess whether the Met allele is overrepresented in unrelated Caucasian male veterans with psychotic PTSD compared to veteran controls. Methods. The BDNF Val66Met variants were genotyped in 576 veterans: 206 veterans without PTSD and 370 veterans with PTSD subdivided into groups with or without psychotic features. Results. Veterans with psychotic PTSD were more frequently carriers of one or two Met alleles of the BDNF Val66Met polymorphism than veterans with PTSD without psychotic features and veterans without PTSD. Conclusions. The study shows that veterans with psychotic PTSD carried more Met alleles of the BDNF Val66Met than non-psychotic veterans with PTSD or veterans without PTSD. The results might add further support to the hypothesis that psychotic PTSD is a more severe subtype of PTSD.