WEDNESDAY, April 19 (HealthDay News) -- Concentrations of the pain-transmitting neuropeptide substance P are elevated in the cerebrospinal fluid of patients with major depression or post-traumatic stress disorder (PTSD) and they increase when PTSD symptoms are provoked, according to a study published in the April issue of the American Journal of Psychiatry.
Thomas D. Geracioti, Jr., M.D., of the University of Cincinnati College of Medicine in Ohio, and colleagues measured substance P concentrations in the cerebrospinal fluid of 40 patients with major depression, eight patients with PTSD and 47 healthy volunteers. They also measured concentrations in PTSD patients after provoking symptoms with a traumatic videotape.
Basal substance P concentrations were elevated in both depressed and PTSD patients. After 10 minutes of traumatic videotape exposure, the PTSD patients' concentrations increased by 169 percent, and by 90.6 percent after 70 minutes. Exposure to a neutral videotape did not increase concentrations.
"These results suggest that elevated central nervous system substance P concentrations are involved in both major depression and PTSD," the authors conclude. "These data provide the pathophysiological rationale for initiation of clinical trials of substance P antagonists in PTSD."