Elsevier

Biological Psychiatry

Volume 45, Issue 7, 1 April 1999, Pages 840-845
Biological Psychiatry

Original Articles
Low platelet-poor plasma concentrations of serotonin in patients with combat-related posttraumatic stress disorder

https://doi.org/10.1016/S0006-3223(98)00231-5Get rights and content

Abstract

Background: Combat-related posttraumatic stress disorder (CR-PTSD) is associated with a dysregulation of various neurotransmitter systems.

Methods: We assessed levels of platelet-poor plasma (PPP) norepinephrine (NE), and serotonin (5-HT), and 24-hour urinary excretion of NE, dopamine (DA), and homovanillic acid (HVA) in 17 male outpatients with untreated chronic CR-PTSD (age, 33.1 ± 7.4 years) and 10 normal control subjects (age, 35.8 ± 2.7 years).

Results: Compared with the control subjects, the PTSD patients showed significantly lower PPP 5-HT levels, elevated PPP NE levels, and significantly higher mean 24-hour urinary excretion of all three catecholamines (NE, DA, and HVA). The 24-hour urinary HVA values of the CR-PTSD patients correlated significantly and positively with the total Impact of Event Scale scores and the avoidance symptoms cluster scores, and the PPP 5-HT levels correlated negatively with the Hamilton Anxiety Rating Scale scores. The PPP NE/5-HT ratio was significantly higher in the study group than in the control subjects.

Conclusions: We believe this combined enhanced noradrenergic activity and diminished 5-HT activity may be relevant to the neurobiology of CR-PTSD.

Introduction

Several studies have described the simultaneous activation of the noradrenergic, dopaminergic, and serotonergic mediated systems immediately following exposure to severe psychological trauma Charney et al 1993, Sutherland and Davidson 1994. This has been suggested to be an adaptive response necessary for survival; however, in cases of posttraumatic stress disorder (PTSD), it may become maladaptive and may lead to a chronic neurobiological dysfunction Charney et al 1993, Southwick et al 1994.

Although PTSD-related activation of the noradrenergic system has been well demonstrated, the mechanism of involvement of the other neurotransmitter systems (e.g., serotonergic and dopaminergic systems) that may be also important in the development and expression of the clinical symptoms of PTSD are less clear Yehuda et al 1992, Southwick et al 1993, Sutherland and Davidson 1994, Weizman et al 1996, Wang et al 1997.

The elevated urinary dopamine (DA), norepinephrine (NE), and epinephrine excretion observed in affected patients indicated that increased catecholaminergic activity is associated with PTSD (Yehuda et al 1992). In addition, the overlap of clinical symptoms of depression, anxiety disorders, and PTSD, together with the relative efficacy of selective serotonin reuptake inhibitors in all these disorders, suggests a possible serotonergic dysregulation in PTSD Nagy et al 1993, Sutherland and Davidson 1994, Weizman et al 1996.

The aim of the present study was to examine the involvement of the serotonergic and catecholaminergic systems in chronic combat-related PTSD (CR-PTSD).

Section snippets

Patients

The study group consisted of 17 male Israeli combat veterans with a primary diagnosis of CR-PTSD. Mean (±SD) age of the group was 33.1 ± 7.4 years, and mean (±SD) duration of PTSD symptoms was 7.8 ± 6.8 years. The diagnosis of PTSD was based on the DSM-III-R criteria and was established during military service; none of the subjects had previous psychiatric treatment prior to that evaluation. The patients were interviewed (by B.S.) according to the guidelines of the Structured Clinical Interview

Results

There was no significant difference between CR-PTSD patients and the healthy control subjects in age (t = 2.1, df = 25, p = .3). Scores on the PTSD scale (study group only) ranged from 22 to 40 points (mean ± SD, 31.9 ± 4.9), and the total IES score was 31.2 ± 3.8; there was no significant difference in the IES score between intrusive and avoidance symptoms (17.5 ± 1.9 and 13.6 ± 3.4, respectively; p = .4). The HDRS score was significantly higher in the CR-PTSD patients (18.7 ± 7.7) than in the

Discussion

Our results are in agreement with previous findings of increased 24-hour urinary catecholamine excretion (NE and DA) as well as the DA metabolite (HVA) in patients with CR-PTSD compared to healthy control subjects Yehuda et al 1992, Kosten et al 1987. Furthermore, the urinary NE and DA measures showed a significant intercorrelation in the PTSD group but not in the control subjects. The correlation between urinary DA and HVA in the PTSD patients did not reach statistical significance, though a

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