Patterns and risk factors of change in somatic and mood symptoms among older adults.

PURPOSE: This paper was concerned with patterns of individual-level, longitudinal change in depressive symptoms and factors related to those patterns among Americans 70+ years of age. Two types of depressive symptoms were considered, somatic and mood symptoms. The paper focused on whether the patterns of change and the risk factors for these two types of symptoms differed, as we might expect among old and oldest-old adults.
METHODS: The analytic sample included self-respondents of the 1993--1995 Asset and Health Dynamics among the Oldest Old (AHEAD) study who were born in 1923 or earlier. Depressive symptoms were assessed using an abbreviated Center for Epidemiologic Studies-Depression (CES-D) Scale. The analyses involved examination of respondents' change scores in depressive symptoms and multivariate models using ordinary least squares (OLS) and seemingly unrelated regressions (SUR).
RESULTS: In aggregate, somatic symptoms were more common than mood symptoms initially and over time. Despite differences in aggregate rates, AHEAD respondents' individual-level patterns of change for the two types of symptoms were similar; i.e., stability was the principal trend (53--60%), followed by improvement (21--26%). A number of factors related to change in one aspect of depressive symptoms and not the other, or had greater effects on one aspect of depressive symptoms than the other; e.g., physical health had greater effects on somatic than mood symptoms.
CONCLUSIONS: This study suggests that, in investigations of the course and risk factors for depressive symptoms among people 70+ years of age, it is important to separate somatic symptoms from mood symptoms; their etiology may differ. In general, factors reflecting respondents' social milieu (e.g., bereavement, residential relocation) may have greater effects on mood than somatic symptoms, whereas certain factors representing physical health may have greater effects on somatic symptoms.