Loneliness is a predictor of mortality and increased cardiovascular morbidity. Since inflammation is a potential pathway through which loneliness might impact health, this study was conducted to investigate the relationship between loneliness and inflammatory interleukin-6 (IL-6), interleukin-1 receptor antagonist (IL-1Ra), and monocyte chemotactic protein-1 (MCP-1) responses to standardized mental stress. A secondary purpose was to evaluate whether individual variations in cortisol responses influenced the hypothesized relationship between loneliness and inflammation. Saliva samples and blood were taken from 524 healthy middle-aged men and women from the Whitehall II cohort at baseline, immediately after stress tasks, and 45 min later. Greater loneliness (measured with the revised UCLA loneliness scale) was associated with larger IL-6 (P = 0.044) and IL-1Ra (P = 0.006) responses to psychological stress and higher MCP-1 (P < 0.001) levels in women (but not men), independently of age, grade of employment, body mass index, and smoking status. Cortisol responsiveness was inversely related to loneliness in women; the odds of being a cortisol responder decreased with increasing loneliness (P = 0.008). Therefore, the impact of loneliness on health in women may be mediated in part through dysregulation of inflammatory and neuroendocrine systems. Psychoneuroendocrinology. 2012 Apr 11. PMID: 22503139
