Memory Trajectories and Disability Among Older Couples: The Mediating Role of Depressive Symptoms

Using a dyadic approach, this study examined the mediating effect of depressive symptoms on the longitudinal relationships between husbands' and wives' memory trajectories and their prospective disability status.

Longitudinal data from the Health and Retirement Study 2004-2018 were used. Older (aged 50+) heterosexual couples who had no limitations in the activity of daily living at the baseline (2004) were included (N = 1,310). Latent class growth analysis grouped wives and husbands into distinct memory trajectories in 2004-2014. A structural equation model examined the actor and partner effects of memory trajectories on depressive symptoms in 2016 and disability status in 2018. The mediating effect of depressive symptoms was tested.

A total of 4 distinct memory trajectories were found: persistently high, high and slow decline, moderate and slow decline, and low and rapid decline. Only the wife's low and rapid decline memory trajectory predicted her own more depressive symptoms (β = 0.588, 95% CI: 0.209, 0.967) and her husband's more depressive symptoms (β = 0.326, 95% CI: 0.004, 0.648). Meanwhile, depressive symptoms had strong and significant actor effects on disability (β = 0.046, 95% CI: = 0.036, 0.057 for wives; β = 0.060, 95% CI: = 0.046, 0.074 for husbands).

The wife's low and rapid decline trajectory was associated with her own and her husband's more depressive symptoms, which in turn increased the disability risk for both partners. Timely identification and treatment of memory decline among wives have the potential to mitigate couples' depressive symptoms and, ultimately, disability risks.