Age-varying association between depression and cognitive function among a national sample of older US immigrant adults: the potential moderating role of physical activity

Objectives This study aimed to (1) investigate age-associated trends in depression and cognition, (2) determine whether the association between depression and cognition varies across age, and (3) test whether this association is moderated by different levels of physical activity among older U.S. immigrant adults aged 60 to 80 years. Methods Using national data on elderly U.S. immigrants (N = 375) from the 2011-2014 NHANES, we employed weighted intercept-only linear time-varying effect modeling (TVEM) and weighted linear TVEM to address our research questions. Results Weighted intercept-only linear TVEM indicated no trend in depression, but its mean peaked at age 67. Cognition consistently decreased with age, reaching its lowest point at age 78. Weighted linear TVEM revealed a significant inverse association between depression and cognition at some age ranges, with the strongest association at around age 66. Yet, we did not find the moderational relation of physical activity to this age-varying association. Conclusions Although we observed a significant inverse relationship between depression and cognition at a certain age point, physical activity did not moderate the age-varying association. Understanding of age-varying effects on the depression-cognition interaction will promote prevention efforts targeting aging immigrant populations at highest risk for these health outcomes. Further work is needed to test moderating effects of other health behaviors on this association across age.