The bidirectional relationship between physical health and memory.

Individuals typically experience changes in physical health and cognitive ability across the life span. Although these constructs dynamically relate to one another, the temporal ordering of dynamic changes in physical health and cognitive ability is not well-established. Therefore, we examined the temporal ordering of the dynamic, bidirectional relationship between physical health and memory across ages 50–87 with Bivariate Dual Change Score Models (BDCSM). Employing a model-comparison approach, we tested whether inclusion of specific directional coupling parameters resulted in a meaningful improvement in model fit, controlling for education, gender, and race. The current sample included 9,103 individuals who participated in Waves 4–11 (1998–2012) of the Health and Retirement Study. Results indicated that both memory and physical health declined across ages 50–87. Furthermore, level of memory at a given time point was positively associated with subsequent change in physical health, meaning higher memory was linked to less decline in physical health by the subsequent time point. The opposite effect, namely physical health predicting memory, was much weaker. Age differences were also evident in the bidirectional coupling model, indicating that old-old individuals (i.e., ages 75–87) exhibited a much stronger coupling effect from memory to change in physical health than younger individuals (i.e., ages 50–74). In conclusion, memory buffers decline in physical health across mid-to-later life, and this effect is especially strong at older ages.