Prosocial effects of MDMA: A measure of generosity.
BACKGROUND
3,4-methylenedioxymethamphetamine (MDMA) produces "prosocial" effects that contribute to its recreational use. Few studies have examined the cognitive and behavioral mechanisms by which MDMA produces these effects. Here we examined the effect of MDMA on a specific prosocial effect, i.e. generosity, using a task in which participants make decisions about whether they or another person will receive money (Welfare Trade-Off Task; WTT).


METHODS
The project included one study without drug administration and one with MDMA. In Study 1, we administered the WTT to healthy adults (N = 361) and examined their performance in relation to measures of personality and socioeconomic status. In Study 2, healthy volunteers with MDMA experience (N = 32) completed the WTT after MDMA administration (0, 0.5, or 1.0 mg/kg).


RESULTS
As expected, in both studies participants were more generous with a close friend than an acquaintance or stranger. In Study 1, WTT generosity was related to household income and trait Agreeableness. In Study 2, MDMA (1.0 mg/kg) increased generosity toward a friend but not a stranger, whereas MDMA (0.5 mg/kg) slightly increased generosity toward a stranger, especially among female participants.


CONCLUSIONS
These data indicate that the WTT is a valuable, novel tool to assess a component of prosocial behavior, i.e. generosity to others. The findings support growing evidence that MDMA produces prosocial effects, but, as with oxytocin, these appear to depend on the social proximity of the relationships. The brain mechanisms underlying the construct of generosity, or the effects of MDMA on this measure, remain to be determined.
Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL, USA Department of Preventive Medicine, University of Southern California, Los Angeles, CA, USA.
Matthew
M
Kirkpatrick
Center for Behavioral Political Economy, Department of Political Science, Stony Brook University, Stony Brook, NY, USA College of Business, Stony Brook University, Stony Brook, NY, USA.
Andrew W
AW
Delton
College of Business, Stony Brook University, Stony Brook, NY, USA.
Theresa E
TE
Robertson
Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL, USA hdew@uchicago.edu.
Harriet
H
de Wit
D000328:Adult; D003071:Cognition / Q000187:drug effects; D004311:Double-Blind Method; D004644:Emotions / Q000187:drug effects*; D004645:Empathy / Q000187:drug effects*; D005260:Female; D006213:Hallucinogens / Q000494:pharmacology*; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D018817:N-Methyl-3,4-methylenedioxyamphetamine / Q000494:pharmacology*; D012919:Social Behavior; D055815:Young Adult
D006213:Hallucinogens; D018817:N-Methyl-3,4-methylenedioxyamphetamine
MDMA; generosity; humans; individual differences; personality; social behavior