PLASMA NOREPINEPHRINE AND 3-METHOXY-4-HYDROXYPHENYLGLYCOL CONCENTRATIONS AND SEVERITY OF DEPRESSION IN COMBAT POSTTRAUMATIC-STRESS-DISORDERAND MAJOR DEPRESSIVE DISORDER

Background: Catecholamines are thought to play a significant role in t he pathophysiology of posttraumatic stress disorder (PTSD), but findin gs in PTSD have been discrepant. Methods: To obtain more information a bout catecholamine activity in PTSD, we sampled plasma norepinephrine (NE) and 3-methoxy-4-hydroxyphenylglycol (MHPG) concentrations over a 24-hour period in men with PTSD (n = 15) and major depressive disorder (MDD) (n = 12), and nonpsychiatric comparison subjects (n = 13), unde r unstimulated conditions. Chronobiological analyses were performed to determine possible changes in the circadian and ultradian release of these hormones. Results: Significant group differences were present fo r mean plasma NE levels (p = .03), but not MHPG. NE levels were signif icantly associated with severity of depression in the PTSD group (p = .002). Therefore, PTSD subjects were further subdivided into those wit h and without a comorbid secondary depression. Increased NE levels wer e only present in PTSD subjects who did not have a secondary depressio n. This study also found no significant group differences on any of th e chronobiological parameters. Conclusions: The results clarify that i ncreased NE levels in PTSD may be confined to the subgroup of subjects who do not have comorbid depression, and as such, may help resolve so me of the discrepancies in the literature regarding basal catecholamin e activity. Biol Psychiatry 1998; 34:56-63 Published 1998 Society of B iological Psychiatry.