Subthreshold depressive symptoms (SDS) increase with age and adversely affect cognition, physical health, and quality of life. Therefore, this retrospective study investigated the cross-sectional and longitudinal associations between the absence or presence of SDS and neuropsychological performance, physical health, and quality of life in a large, representative sample of older adults aged 55 + .

Data on cognition, physical variables, and psychosocial measures from a healthy subsample of participants aged 55 to 87 years from the population-based 1000BRAINS study were retrospectively analyzed. Cross-sectional data were available for 6691000BRAINS participants, and longitudinal data for 255 participants. The relationship between the absence or presence of SDS and neuropsychological, physical health, and psychosocial measures was examined by linear regression models and repeated-measures analysis of covariance, adjusted for age, sex, educational level, and multiple comparisons.

Greater severity of SDS at baseline was linked to poorer performance in cognitive domains, including processing speed, executive function, figural and verbal memory, and in the dementia screening test, lower physical activity levels, and more physical complaints. Increased SDS over time correlated with accelerated vascular ageing, higher body mass index, and lower quality of life.

In older adults, SDS are associated with impaired cognitive function and lower physical activity levels and quality of life. Further research in the field of early recognition of late-life depression should assess cognition and physical health to identify clinical factors and their interaction in the development of late-life depression.