Physiologic dysfunction scores and cognitive function test performance in U.S. adults.

OBJECTIVE: To investigate the relationship between a measure of cumulative physiologic dysfunction and specific domains of cognitive function.
METHODS: We examined a summary score measuring physiologic dysfunction, a multisystem measure of the body's ability to effectively adapt to physical and psychological demands, in relation to cognitive function deficits in a population of 4511 adults aged 20 to 59 who participated in the Third National Health and Nutrition Examination Survey (1988-1994). Measures of cognitive function comprised three domains: working memory, visuomotor speed, and perceptual-motor speed. "Physiologic dysfunction" scores summarizing measures of cardiovascular, immunologic, kidney, and liver functions were explored. We used multiple linear regression models to estimate associations between cognitive function measures and physiologic dysfunction scores, adjusting for socioeconomic factors, test conditions, and self-reported health factors.
RESULTS: We noted a dose-response relationship between physiologic dysfunction and working memory (coefficient = 0.207, 95% confidence interval = 0.066-0.348, p < .0001), which persisted after adjustment for all covariates (p = .03). We did not observe any significant relationships between dysfunction scores and visuomotor (p = .37) or perceptual-motor ability (p = .33).
CONCLUSIONS: Our findings suggest that multisystem physiologic dysfunction is associated with working memory. Future longitudinal studies are needed to clarify the underlying mechanisms and explore the persistency of this association into later life. We suggest that such studies should incorporate physiologic data, neuroendocrine parameters, and a wide range of specific cognitive domains.