Effects of MDMA on sociability and neural response to social threat and social reward.
BACKGROUND
+/-3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") reportedly produces unique subjective effects, including increased sociability, feelings of closeness with others, and reduced interpersonal defensiveness. Despite their apparent importance in recreational and potential psychotherapeutic use of MDMA, the defining characteristics and neurobiological mechanisms of these interpersonal effects are poorly understood.


METHODS
We investigated acute effects of MDMA on self-reported sociability and neuronal activation in response to socially threatening (angry and fearful faces) and socially rewarding (happy faces) stimuli. Assessment of social threat response focused on amygdala activation, whereas assessment of social reward focused on ventral striatum activation. Healthy volunteers (N = 9) reporting past ecstasy use completed three experimental sessions, receiving MDMA (0.75 and 1.5 mg/kg) and placebo (PBO) under double-blind conditions. During peak drug effects, participants underwent functional magnetic resonance imaging while viewing standardized images depicting emotional facial expressions including angry, fearful, happy, and neutral expressions. They also completed standardized self-report measures of sociability.


RESULTS
MDMA (1.5 mg/kg) increased self-reported sociability compared to MDMA (0.75 mg/kg) and PBO. MDMA (1.5 mg/kg) attenuated left amygdala response to angry facial expressions compared to PBO, but MDMA did not affect amygdala reactivity to fearful expressions. MDMA (0.75 mg/kg) enhanced ventral striatum response to happy expressions relative to PBO.


CONCLUSIONS
These data present the first evidence that MDMA may increase sociability in humans both by diminishing responses to threatening stimuli and enhancing responses to rewarding social signals.
Bedi
Gillinder
G
Human Behavioral Pharmacology Laboratory, Department of Psychiatry, University of Chicago, 5841 S. Maryland Ave, MC 3077, Chicago, IL 60637, USA.
Phan
K Luan
KL
Angstadt
Mike
M
de Wit
Harriet
H
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000098:blood supply / Q000187:drug effects*; D001931:Brain Mapping; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004644:Emotions / Q000187:drug effects* / Q000502:physiology; D006213:Hallucinogens / Q000009:adverse effects*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D018817:N-Methyl-3,4-methylenedioxyamphetamine / Q000009:adverse effects*; D010100:Oxygen / Q000097:blood; D010147:Pain Measurement; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D012201:Reward; D012919:Social Behavior; D055815:Young Adult
D006213:Hallucinogens; D018817:N-Methyl-3,4-methylenedioxyamphetamine; D010100:Oxygen
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