Social isolation, loneliness and the relationship with serum biomarkers, functional parameters and mortality in older...

Pathways between social isolation (SI), loneliness and health are unclear.

To analyze the relationship between SI and loneliness with biomarkers of inflammation, cardiac and immune function, functional parameters, and mortality.

SI (Lubben Social Network Scale) from family, friends, and overall as well as loneliness (single direct question) were assessed at baseline in a population-based cohort study of 1459 community-dwelling adults aged 65 + in Germany. Serum biomarkers and functional parameters measured at baseline and at three-year follow-up included high-sensitivity C reactive protein (hs-CRP), growth differentiation factor-15 (GDF-15), N-terminal pro-brain natriuretic peptide (NT-proBNP), high-sensitivity troponin I (hs-cTnI), high-sensitivity troponin T (hs-cTnT), gait speed, and hand grip strength. We used linear and Cox regression analyses adjusted for age and sex (model 1) and established confounders (model 2).

High SI from friends was associated with small but significant adverse associations with some biomarkers (hs-CRP, GDF-15, hs-cTnT) at follow-up (model 1). High SI from family associated with NT-proBNP (model 2), high SI and moderate to severe loneliness with lower gait speed. Loneliness was linked to hs-CRP at baseline, but SI was a stronger predictor of biomarker levels. High SI overall (Hazard ratio 1.39, 95% CI 1.15; 1.67, model 2) was associated with increased 10-year mortality.

Mainly SI from friends is linked to unfavorable biomarker profiles with small associations. Overall SI was negatively associated with functional parameters and positively with mortality.

Further research should confirm our findings using, e.g. a multidimensional assessment of loneliness.