Four decades of psychoneuroimmunology research from Kiecolt-Glaser's lab at Ohio State establishes a robust causal chain: psychosocial adversity — including marital discord, loneliness, dementia caregiving, and examination stress — reliably degrades immune competence. Specific documented effects include impaired vaccine immunogenicity with faster antibody waning, slowed wound healing, heightened systemic inflammation, and accelerated cellular aging (likely telomere attrition, based on this research group's prior work). Depression compounds this by sensitizing immune reactivity, producing exaggerated inflammatory responses to subsequent stressors. Newer mechanistic work implicates gut microbiome disruption and intestinal permeability as mediating pathways linking social stress to systemic inflammation.
This is not incremental science — it is a consolidation of arguably the most important behavioral-immune evidence base in medicine. What makes this body of work paradigm-relevant is the specificity of effect: distressed relationships alter postprandial inflammatory and endothelial responses, meaning a hostile marriage changes how your body metabolizes a meal. The gut-brain-immune axis extension is particularly significant, as it bridges social psychology with microbiome research in a mechanistically coherent way. For adults, the practical implication is stark: relationship quality and loneliness function as physiological risk factors comparable to diet or sedentary behavior. Limitations here are inherent to a review synthesizing decades of heterogeneous studies — effect sizes and replication consistency vary. But the directional evidence is unusually convergent, and the note that behavioral and nutritional interventions can modify these trajectories offers genuine clinical leverage.