Serotonin receptors and suicide, major depression, alcohol use disorder and reported early life adversity

Abstract

Serotonin neurotransmitter deficits are reported in suicide, major depressive disorder (MDD) and alcohol use disorder (AUD). To compare pathophysiology in these disorders, we mapped brain serotonin transporter (SERT), 5-HT _1A, and 5-HT _2A receptor binding throughout prefrontal cortex and in anterior cingulate cortex postmortem. Cases and controls died suddenly minimizing agonal effects and had a postmortem interval ≤24 h to avoid compromised brain integrity. Neuropathology and toxicology confirmed absence of neuropathology and psychotropic medications. For most subjects (167 of 232), a DSM-IV Axis I diagnosis was made by psychological autopsy. Autoradiography was performed in right hemisphere coronal sections at a pre-genual level. Linear model analyses included sex and age with group and Brodmann area as interaction terms. SERT binding was lower in suicides ( p = 0.004) independent of sex (females < males, p < 0.0001), however, the lower SERT binding was dependent on MDD diagnosis ( p = 0.014). Higher SERT binding was associated with diagnosis of alcoholism ( p = 0.012). 5-HT _1A binding was greater in suicides ( p < 0.001), independent of MDD ( p = 0.168). Alcoholism was associated with higher 5-HT _1A binding ( p < 0.001) but only in suicides ( p < 0.001). 5-HT _2A binding was greater in suicides ( p < 0.001) only when including MDD ( p = 0.117) and alcoholism ( p = 0.148) in the model. Reported childhood adversity was associated with higher SERT and 5-HT _1A binding ( p = 0.004) in nonsuicides and higher 5-HT _2A binding ( p < 0.001). Low SERT and more 5-HT _1A and 5-HT _2A binding in the neocortex in depressed suicides is dependent on Axis I diagnosis and reported childhood adversity. Findings in alcoholism differed from those in depression and suicide indicating a distinct serotonin system pathophysiology.