Persistence and Determinants of Late-Life Depression: Results of the Nationally Representative Longitudinal German Aging Survey 2008 to 2023.

OBJECTIVES: Late-life depression is the most common mental disorder in older adults. As symptom progression and risk factors are not well understood, this study focuses on longitudinal symptom progression and time-varying risk factors. METHODS: Longitudinal data of adults aged 60+ were drawn from six waves (2008-2023) of the German Aging Survey (DEAS), with the largest analytic sample in 2014 (n = 6515). At each wave participants were classified as having "no" (0-9), "minor" (10-17) or "major" (18-45) depressive symptoms (DS) based on the German Center for Epidemiologic Studies Depression Scale (CES-D). Persistent DS were defined as PDS (at least minor DS) or majorPDS (major DS) across two consecutive waves. Weighted transition probabilities between DS stages were calculated across all person-years. Linear fixed effects regression with cluster-robust standard errors was used to identify time-varying determinants of DS. RESULTS: In 2014, the prevalence rate was 17.4% [16.6%-18.1%] for minor DS, 7.2% [6.6%-7.8%] for major DS, 12.2% [11.3%-13.1%] for PDS and 2.5% [2.0%-3.1%] for majorPDS. Estimates were similar across all six waves. Minor DS frequently persisted (37.3% [34.1%-40.6%]) or progressed to major DS (11.7% [9.6%-14.2%]). Major DS persisted in 38.6% [31.1%-46.7%] and remitted to minor DS in 31.8% [25.9%-38.3%] of cases. Transition to widowhood (β = 0.67, p < 0.05), worsening of physical functioning (β = -0.06, p < 0.01), increasing loneliness (β = 1.02, p < 0.01), worsening of sleep quality (β = 0.78-4.40, p < 0.01) and decreasing BMI (β = -0.08, p < 0.01) were associated with increases in DS. CONCLUSIONS: DS are common in later life and are frequently persistent. Minor DS often persist or worsen, underscoring their role as a key risk factor. Major DS frequently remits only partly. Early, targeted interventions could be informed by modifiable determinants that may also help to allocate scarce mental health resources effectively.