Longitudinal analysis of loneliness and inflammation at older ages: English longitudinal study of ageing.

Loneliness has been associated with adverse health outcomes, including age-related diseases with an inflammatory etiology such as cardiovascular disease. We aimed to identify potential biological pathways linking loneliness with morbidity and mortality by examining associations of loneliness with biomarkers. Participants in the English Longitudinal Study of Ageing (n = 3239) aged 50 years or older with an average age of 64 years, provided data in waves 4 (2008/2009) and 6 (2012/2013). Linear regression conditional change models had three outcomes: C reactive protein (CRP) measured in mg/L (log transformed), fibrinogen in g/L and ferritin in g/dL. In men, the onset of loneliness indicated by answering 'no' at wave 4 and 'yes' at wave 6 to question "Much of the time during the past week, you felt lonely?" was associated with a statistically significant increase in levels of CRP (β = 0.36, 95% confidence interval (0.09 to 0.62)), plasma fibrinogen (0.18 (0.04 to 0.31)) and ferritin (41.04 (6.58 to 75.50)), after full adjustment. A statistically significant increase in CRP in men was also observed for onset of loneliness assessed with the question "How often do you feel lonely?" (0.20 (0.03 to 0.38)). These associations were not mediated by depressive symptoms. Persistent loneliness (loneliness experienced at both baseline and follow-up) assessed using the University of California Los Angeles (UCLA) loneliness scale was associated with an increase in CRP (0.11 (0.004 to 0.22)) among men. Associations of the two latter loneliness measures with fibrinogen and ferritin were mainly null. Among women, the only statistically significant association was for persistent loneliness (loneliness at both waves) identified by question "Much of the time during the past week, you felt lonely?" with a reduction in levels of ferritin (-20.62 (-39.78 to -1.46)). Men may be more susceptible to loneliness-associated disease risks signaled by biological changes, including systemic inflammation. Combined social and targeted medical interventions may help to reduce health risks associated with loneliness.