Bidirectional longitudinal associations between loneliness and pain, and the role of inflammation.

ABSTRACT: Pain and loneliness are consistently associated, but the direction of the relationship is uncertain. We assessed bidirectional associations over a 4-year period in a sample of 4906 men and women (mean 65.1 ± 8.72 years) who were participants in the English Longitudinal Study of Ageing. The role of inflammation in these links was also investigated. Pain was defined by reports of being often troubled by pain at a moderate or severe intensity, whereas loneliness was measured using the shortened UCLA scale. Age, sex, ethnicity, educational attainment, wealth as a marker of socioeconomic resources, marital status, physical activity, and depressive symptoms were included as covariates. We found that baseline loneliness was associated with pain 4 years later after adjusting for baseline pain and other covariates (odds ratio [OR] = 1.25, 95% confidence interval [CI] 1.06-1.47, P = 0.007). Similarly, baseline pain independently predicted loneliness 4 years later (OR = 1.34, 95% CI 1.14-1.58, P = 0.001). Associations remained significant after additional adjustment for baseline mobility impairment. Likelihood of pain on follow-up was heightened when baseline loneliness was accompanied by elevated C-reactive protein concentration (OR = 1.50, 95% CI 1.13-2.00, P = 0.006), whereas inflammation did not predict future loneliness or contribute to the association between baseline pain and future loneliness. Both pain and loneliness are distressing experiences that impact well-being and quality of life. We conclude that there were bidirectional longitudinal relationships between pain and loneliness in this representative sample of older men and women, but that the mechanisms underlying these processes may differ.