Understanding How Trait Negative Emotionality (NEM) Influences Social Connectedness and Responses to ± 3,4-Methylenedioxymethamphetamine (MDMA)

Summary

Negative Emotionality (NEM) does not appear to influence feelings of social connectedness after a closeness-building procedure in healthy volunteers. While NEM was not linked to baseline friendliness or changes in social connectedness, it showed a trend toward greater MDMA-induced peak friendliness change. Additionally, NEM predicted MDMA-induced oxytocin release when considering sex differences. These findings suggest that personality traits may affect drug responses and highlight the need for further research in clinical populations.

Study at a glance

Abstract

Negative Emotionality (NEM) is a trait measure that reflects a tendency toward experiencing intense negative emotions and heightened reactivity to perceived threats or stressors, contributing to challenges with social integration and interpersonal relationships. This secondary analysis in healthy volunteers (N = 30) employed a within-subject, double-blind, placebo-controlled design to investigate whether trait NEM influences feelings of social connectedness after a closeness-building procedure, as well as subjective and neurobiological responses to ±3,4-methylenedioxymethamphetamine (MDMA). Results indicated that NEM was not associated with baseline ratings of friendliness or changes in social connectedness after a closeness-building procedure. Higher NEM showed a trend-level association with greater MDMA-induced peak friendliness change (p = .056). In an exploratory model including sex and NEM × Sex interaction, NEM predicted MDMA-induced oxytocin release after accounting for sex (p = .049). Although the small sample size and non-clinical population render these findings preliminary, they highlight the importance of considering individual differences in personality that may shape drug response. They also point to the need for accounting for sex differences in drug-related research, particularly when evaluating the efficacy and underlying mechanisms of drug-assisted clinical interventions. As MDMA-assisted therapy advances through clinical trials for psychiatric conditions associated with elevated NEM, understanding which populations exhibit the strongest neurobiological responses has direct implications for patient selection, dose optimization, and addressing treatment heterogeneity. Future research should assess these interactions within clinical populations, where the functional impact of NEM is more pronounced.

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