Psychosocial stress and autoimmune thyroid disease: a systematic review of clinical phenotypes and vulnerability factors.

Psychological stress has been proposed as a potential trigger or modulator of autoimmune thyroid diseases, but evidence remains fragmented. This systematic review examined the relationship between stress and thyroid autoimmunity, with particular attention to Hashimoto's thyroiditis and Graves' disease, highlighting the critical methodological distinction between stressor exposure (objective events) and the subjective stress response (psychological burden). PubMed, Embase, Scopus, and PsycINFO were searched for controlled human studies; 25 studies involving a total of N = 117,034 participants met the inclusion criteria and were synthesized narratively across seven analytical categories. Substantial heterogeneity precluded a meta-analysis, partly driven by the predominance of measures of stressful life events (15 studies; 60%) over assessments of the subjective stress response (4 studies; 16%). Findings demonstrate that associations are critically phenotype-dependent and contingent on the stress construct evaluated. For Graves' disease, evidence reveals a robust association with stressful life events, acting as a significant precipitating factor for disease onset and relapse. In contrast, Hashimoto's thyroiditis is more closely linked to a high subjective stress response, which functions as an amplifier of disease activity and autonomic dysfunction. Early-life adversity and genetic susceptibility (e.g., HLA-Cw7) emerge as key vulnerability factors that reset biological regulation thresholds through 'biological embedding'. Mechanistically, stress contributes to neuroendocrine-immune dysregulation via hypothalamic-pituitary-adrenal axis and sympathetic activation, facilitating the breakdown of immunological tolerance. These findings highlight the clinical necessity of incorporating psychosocial assessments into the management of autoimmune thyroid conditions.