Longitudinal Coupling Between Depressive and Cognitive Symptoms in Ageing and Dementia: A Multi‐Cohort Analysis

Background

Depression and cognition have a complex bidirectional relationship in adulthood and later life. This association is likely heterogeneous, differing between individuals. Further complicating this association is the possible influence of unseen neuropathological changes: any associations between depression and cognitive symptoms may differ in normal and pathological ageing.

We therefore aimed to examine the longitudinal coupling between depressive and cognitive symptoms in later life across multiple ageing cohorts drawing from population settings, memory services, and from a national dementia brain bank.

Method

Repeated data on cognitive performance and self‐ or informant‐reported depressive symptoms were drawn from multiple cohorts: three population ageing studies, CFAS (n = 17,807), Whitehall II (n = 8249) and ELSA (n = 17,980); MEMENTO (n = 2306), a clinical cohort of people with subjective/mild cognitive impairment (S/MCI); BDR (n = 584), a clinico‐pathological cohort with autopsy‐confirmed dementia‐related neurological disease.

Intercept and growth parameters for depressive and cognitive symptoms, and correlations between these, were estimated with bivariate latent growth models.

Result

The relationships between depressive and cognitive symptoms differed substantially between cohorts across the ageing continuum. In early ageing and S/MCI, worse cognitive performance was associated with worsening depression over time (r = 0.12, p = 0.022), whereas in clinical dementia groups and those with autopsy‐confirmed neurological disease, worse cognitive performance was associated with improving depression over time (r = ‐0.30, p = 0.008 and r = ‐0.49, p = 0.023, respectively).

Conclusion

Age‐related associations between cognitive and depressive symptoms may differ between specific ageing populations. When attempting to understand the relationship between depressive and cognitive trajectories, researchers should consider the position of the given sample along this healthy‐pathological ageing continuum.