Sensory gating in chronic posttraumatic stress disorder: Reduced auditory P50 suppression in combat veterans

Background: Posttraumatic stress disorder (PTSD) may be associated with a g eneral impairment of cognitive function that extends beyond the processing of trauma-specific stimuli Suppression of the auditory P50 response to repe ated stimuli occurs in normal subjects and reflects the central nervous sys tem's ability to screen out repetitive stimuli, a phenomenon referred to as sensory gating. This study examines P50 sensory gating to nonstartle audit ory stimuli in PTSD subjects and normal controls. Methods: P50 generation and gating were studied using a conditioning/testin g paradigm in 15 male subjects with PTSD and 12 male controls. P50 test/con ditioning (T/C) ratios were estimated using the Singular Value Decompositio n method. Results: The amplitude of the P50 response to the conditioning stimulus did nor differ in subjects with PTSD compared to normal controls. The P50 T/C ratio is increased in PTSD subjects (mean = .408, SD = .275) as compared to the controls (mean = .213, SD = .126, two tailed t, p = .024), Conclusions: This study provides evidence that PTSD is associated with impa ired gating to nonstartle trauma-neutral auditory stimuli Biol Psychiatry 1 999;46:1656-1664.