The longitudinal effect of depression on functional limitations and disability in older adults: an eight-wave prospective community-based study

Background. The temporal relationship between depression and adverse functi onal outcomes in older adults is ambiguous. In the present eight-wave prosp ective community-based study, the longitudinal effect of depression on func tional limitations and disability (in terms of disability days and bed days ) was studied, thereby taking into account the role of chronic physical dis eases. Methods. The study is based on a sample which at the outset consisted of 32 5 non-depressed and 327 depressed persons (55-85 years) drawn from a larger random community based sample in the Netherlands. Generalized estimating e quations time-lag models were used to examine the longitudinal relation bet ween depression and both functional limitations and disability. Results. Functional limitations were very persistent over time, whereas dis ability days and bed days were more fluctuating functional outcomes. Only i n the presence of chronic physical diseases, there was a significant longit udinal association between depression at the previous measurement and funct ional limitations, disability days and bed days at the next measurement. Th e effect on functional limitations was small, which was probably partly due to their persistent nature. Conclusions. The finding of a longitudinal relationship between depression and functional outcomes in older adults with a compromised health status pr ovides a rationale for treatment of chronic physical diseases as well as de pression in depressed chronically ill elderly, in order to prevent a spiral ling decline in psychological and physical health.