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Intensity dependence of auditory P2 in monozygotic twins discordant for Vietnam combat: Associations with posttraumatic stress disorder

Linda J. Metzger, PhD, et al.

Figure. Mean and standard error P2 amplitudes measured at CZ, plotted as function of tone intensity for female Vietnam nurse veterans with current posttraumatic stress disorder (PTSD) and those who never had PTSD.

Research suggests that brain responses to tones of increasing intensities may reflect functioning of the neurotransmitter serotonin. We measured the P2 brain response to tones of four different intensities in Vietnam veterans and their identical twins who did not serve in Vietnam. Veterans with posttraumatic stress disorder (PTSD) showed increased P2 amplitude with greater tone intensity, a pattern referred to as increased intensity dependence. Their identical cotwins did not share this pattern, suggesting that increased intensity dependence is a consequence of PTSD. Findings suggest that some veterans with PTSD may experience low serotonin and may benefit from treatment with selected serotonin reuptake inhibitors.


Volume 45 Number 3, 2008
   Pages 437 — 450

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