Stress and Gene-Environment Interplay: The Role of Stress, Loneliness, and Genetics on Mental Health Trajectories
Year: 2026
Type: dissertation
Study design: Observational Study
Abstract: Psychological vulnerability is not fixed at birth but unfolds dynamically across development, shaped by the continuous interplay between genetics and everyday experience. This thesis examines how genetic risk for depression and anxiety, stress, and loneliness jointly shape emotional functioning in daily life, bringing together polygenic scores (PGS) and ecological momentary assessment (EMA) to capture this interplay as it occurs in real time. The thesis proceeds across three empirical and review chapters. Chapter 2 provides a narrative review of the PGS gene–environment interaction (GxE) literature on stress-related psychopathology, synthesizing evidence for the diathesis–stress framework and identifying where support is most consistent and where gaps remain. Chapter 3 applies moderated network analysis to four days of experience-sampling data from 413 adults, testing whether daily stress reorganizes the relational structure of negative affect rather than simply its overall level. Chapter 4 extends this approach genetically, using polygenic scores derived from large-scale genome-wide association studies alongside a genotyped, multi-site EMA sample (N = 168–192) to test whether polygenic risk for depression and anxiety predicts stress reactivity, average emotional functioning, and day-to-day variability. No evidence was found for the classic amplification hypothesis, whereby genetic risk would heighten emotional reactivity to daily stressors. Genetic risk was instead associated with greater stability in day-to-day loneliness, a finding that survived adjustment for demographic and ancestry covariates and points toward stabilization as a candidate mechanism linking genetic liability to emotional experience. Complementing this, daily stress did not selectively alter specific emotion-to-emotion connections within the negative affect network, indicating that the co-occurrence structure of negative emotions remains largely stable across fluctuating stress levels. Together, these findings challenge the assumption that genetic risk operates primarily by intensifying reactivity to environmental stressors, and instead point toward stabilization as an underexplored mechanism linking genetic liability to emotional experience in daily life. The thesis argues that understanding mental health risk requires methods capable of jointly capturing genetic predisposition and moment-to-moment environmental experience, and discusses implications for future gene-environment interaction research using intensive longitudinal designs.
Author: KOURIS, Mehves
Institution: University of Luxembourg
Language: English
Subfield: Experimental and Cognitive Psychology
Field: Psychology
Domain: Social Sciences
Open Access status: green
OpenAlex ID: W7204517365