Reducing loneliness among older adults may prevent future depressive symptoms

Older adults with higher levels of loneliness were at increased risk for more severe depression symptoms, according to results of a population-based cohort study published in The Lancet Psychiatry.

“Many studies have examined the relationship between loneliness and depression in older adults, but these studies have had limitations,” Siu Long Lee, MSc, of the division of psychiatry at University College London, and colleagues wrote. “There have been several cross-sectional studies, but it is impossible to rule out reverse causation in studies with a cross-sectional design. Longitudinal studies are essential to establishing whether loneliness precedes depressive symptoms, which is a necessary condition for identifying loneliness as a potentially causal, and hence targetable, risk factor for depression.”

Lee and colleagues sought to determine whether loneliness was linked to more severe symptoms of subsequent depression by analyzing seven waves of data collected once every 2 years between 2004 and 2017 of adults aged 50 years and older who were included in the English Longitudinal Study of Ageing. Loneliness at baseline, measured via the short 1980 revision of the UCLA Loneliness Scale, served as the exposure. Severity of depression measured at six subsequent timepoints via the eight-item version of the Centre for Epidemiologic Studies Depression Scale (CES-D) served as the primary outcome. The researchers used linear multilevel regressions for analysis, which they adjusted before and after for social isolation, social support, polygenic risk scores and other sociodemographic and health-related confounders. Depression diagnosis, measured using a binary version of the CES-D.

Complete exposure, outcome and confounder data were available for 4,211 eligible participants. Results showed a one-point increase in loneliness score linked to a 0.16 (95% CI, 0.13-0.19) increase in depressive symptom severity score after all adjustments. The researchers estimated a population attributable fraction for depression linked to loneliness of 18% (95% CI, 12-24) at 1 year of follow-up and 11% at the final follow-up. This suggested that between 11% and 18% of depression cases may have been prevented if loneliness were eliminated, Lee and colleagues noted. Further, after 12 years of follow-up, associations between loneliness and depressive symptoms remained; however, effect sizes were smaller with longer follow-up.

“Although tackling loneliness effectively will be a complex task, it has important potential to reduce or even prevent future depressive symptoms in older adults,” Lee and colleagues wrote.