To examine autonomic responses to social exclusion in monozygotic and dizygotic twins with and without symptoms of functional gastrointestinal disorders (FGID) and eating disorders (ED).
Approach:
Participants: 35 monozygotic and dizygotic twin pairs were studied, with zygosity determined via genetic blood testing.
Group Assignment: Participants were divided into four groups based on questionnaire data: ED-related symptoms, FGID-related symptoms, combined symptoms, and asymptomatic controls.
Experimental Task: All participants completed a controlled social exclusion task using the Cyberball paradigm.
Measurements: Heart rate variability (HRV), skin conductance (SC), skin temperature (ST), and subjective stress ratings (VAS) were assessed during baseline, exclusion, and recovery phases.
Analysis: Exploratory group comparisons, twin-based concordance, intraclass correlations, and Falconer estimates were performed.
Key Findings:
Significant changes in SC, ST, HRV, and VAS across experimental phases confirmed successful stress induction and recovery.
No significant differences were found between symptom groups.
Zygosity-related interactions were observed for selected HRV indices and birth-order effects in VAS.
Non-shared environmental factors may contribute to variability in physiological stress response.
Genetic influences were noted for subjective stress ratings and selected HRV indices.
Interpretation:
Social exclusion induced autonomic and subjective stress responses across all participants, independent of symptom status. Exploratory twin analyses suggest both environmental and genetic factors may influence individual differences in stress reactivity.
Limitations:
Limited sample size.
Exploratory nature of the analyses.
Conclusion:
Findings should be regarded as hypotheses-generating and require replication in larger twin cohorts.
