Serotonin and sensitivity to trauma-related exposure in selective serotonin reuptake inhibitors-recovered posttraumatic stress disorder

BackgroundSelective serotonin reuptake inhibitors (SSRIs) are first-line treatments for posttraumatic stress disorder (PTSD). Serotonergic (5HT) attenuation of stress sensitivity is postulated from SSRIs' effects in other anxiety disorders, and we studied this in PTSD.MethodsTen patients with PTSD fully recovered on SSRIs (Clinical Global Impression Scale—I 1 and 2) were enrolled in the study. Patients were tested on two occasions 1 week apart; in each session, they received a drink containing large neutral amino acids (LNAAs) either with (sham tryptophan depletion [STD], control) or without (acute tryptophan depletion [ATD]) tryptophan. At 5.5 hours after the drink, subjects were exposed to a trauma-related exposure challenge. Self-reports of PTSD (visual analogue scales [VAS] and the Davidson Trauma Scale [DTS]), anxiety (Spielberger State Inventory [STAI] Form Y-1), and mood (Profile of Mood States [POMS]) were obtained. Heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure were also measured.ResultsThe trauma-related exposure challenge induced anxiety on both days, with more marked responses on the ATD day according to VAS, DTS, POMS, and DBP (p <.05). A trend of significance (.1 > p > .05) was observed for STAI Form Y-1, HR, and SBP.ConclusionsThese data demonstrate that ATD accentuates responses to trauma-related stimuli in SSRI-recovered PTSD. They also suggest that SSRI-induced increases in serotonin function restrain PTSD symptoms, especially under provocation, supporting a role for serotonin in mediating stress resilience.