The Effects of Depressive Symptomatology and Postural Reserve on Physical Functioning in Older Adults

Abstract

The Effects of Depressive Symptoms and Postural Reserve on Physical Functioning Previous research has demonstrated the high prevalence and societal costs of depressive symptomatology in older adults and its strong association with physical decline. Decreased physical functioning, including decline in gait, is associated with increased mortality and risk of falls. While the relationship between depressive symptoms and physical functioning is well established, individual intrinsic factors that contribute to this relationship are less understood. Postural reserve is a putative construct comprised of factors that underlie critical postural control abilities including musculoskeletal function, sensory feedback systems, motor integration, adaptive/anticipatory mechanisms, and cortical control. Given that postural reserve is an independent factor that may relate to both physical as well as emotional functioning, the primary aim of the study was to examine the relationship between depression, postural reserve, and subcomponents of physical functioning. Specifically addressed were both the individual and additive effects of depressive symptoms and postural reserve on elements of the Short Physical Performance Battery (SPPB). Additionally, the moderating influence of postural reserve on the relationship between depressive symptomatology and physical functioning was assessed. Participants were 418 healthy older adults (57% female) from the Central Control of Mobility in Aging (CCMA) study who were administered the SPPB, a comprehensive gait assessment by the study neurologist, and the Geriatric Depression Scale (GDS). Hierarchical linear regressions were conducted to assess the effect of depression and postural reserve both separately and collectively on overall score and subcomponents of the SPPB. Additionally, conditional process analysis with bootstrapping methods was conducted using depressive symptomatology as the independent factor, gait velocity as the dependent factor, and postural reserve as the moderator. Results revealed significant relationships between depressive symptomatology and gait velocity and balance, but not chair-rise time. Postural reserve was correlated with all SPPB subcomponents both individually and in conjunction with depressive symptomatology. Postural reserve was not found to moderate the relationship between depressive symptomatology and physical functioning. The results underscore the utility of postural reserve as a tool to predict physical functioning and also suggest that increased level of depressive symptoms may indicate greater risk for some, but not all, aspects of physical decline.