Cognitive and functional decline in adults aged 75 and older.

OBJECTIVES: To simultaneously examine the influence of functional disability on the development of cognitive impairment and the influence of cognitive status on the development of functional disability over time and compare findings across ethnic groups.
DESIGN: A population-based longitudinal study.
SETTING: Galveston County, Texas. PARTICIPANTS: Three hundred sixty-five community-dwelling Hispanic Americans, African Americans, and non-Hispanic whites, aged 75 and older. MEASUREMENTS: Baseline measures included demographics, self-reported chronic medical conditions, functional disability, and cognitive status. Longitudinal measures included functional decline and cognitive decline.
RESULTS: Substantial functional decline was associated with each additional error on the mental status measure; substantial cognitive decline was associated with each additional antecedent disability. These findings were evident across all three ethnic groups, even when taking into account the effects of demographic factors and chronic health conditions, although the specific chronic health conditions that influenced cognitive and functional decline were found to vary across the three ethnic groups.
CONCLUSION: Our findings suggest that, rather than simply being correlated markers of increasing frailty, cognitive and functional decline appear to influence the development of one another. Clinicians need to be aware of these associations, which may affect the direction of preventive care and rehabilitation in the oldest old. Appropriate intervention may result in the prevention or delay of functional disability and cognitive decline. Awareness of the specific chronic health conditions that increase the risk for cognitive or functional decline in various ethnic groups, and the effect of comorbid disease, may also help efforts to prevent decline in older adults.