Acute Tryptophan Depletion and Self-Injurious Behavior in Aggressive Patients and Healthy Volunteers
An association between serotonin (5-HT) activity and self-injurious (i.e., self-aggressive) behavior across the spectrum of lethality (from self-mutilation through completed suicide) is a well-replicated finding. Studies to date, however, have relied on nonexperimental designs to examine this relationship, limiting the causal inferences that can be drawn about the role of 5-HT in self-aggressive behavior. Examine the effect of experimentally altered 5-HT activity (via dietary tryptophan depletion) on self-aggressive behavior among adults with and without intermittent explosive disorder (IED). Individuals with a marked history of aggression, such as those with IED, are characterized by compromised 5-HT and heightened risk for self-aggression, making this a population of interest for examining the proposed relations. IED patients (n = 16) and healthy controls (n = 16) received a tryptophan depletion and a placebo drink on separate days at least 1 week apart. Self-aggressive behavior was assessed on both study days using a well-validated laboratory-based behavioral assessment with self-aggression defined as the intensity of shock self-administered. Tryptophan depletion facilitated selection of more intense shocks, on average, in both groups. Patients with IED were also more self-aggressive overall than healthy volunteers. No IED by drink condition interactions were found. Experimentally lowered 5-HT bioavailability enhances overall self-injurious behavior irrespective of aggression history.
McCloskey, M. S.,
Berman, M. E.,
Coccaro, E. F.
(2009). Acute Tryptophan Depletion and Self-Injurious Behavior in Aggressive Patients and Healthy Volunteers. Psychopharmacology, 203(1), 53-61.
Available at: http://aquila.usm.edu/fac_pubs/1188