Biracial Population Study of Mortality in Mild Cognitive Impairment and Alzheimer Disease

Objective: To assess mortality associated with mild cognitive impairment (MCI) and Alzheimer disease (AD) among older African Americans and whites from an urban community. Design: Longitudinal population-based observational study. Setting: Four adjacent neighborhoods in Chicago, Illinois. Participants: Persons deemed free of dementia in a previous wave of data collection (n = 1715) underwent detailed clinical evaluation: 802 had no cognitive impairment (46.8%), 597 had MCI (34.8%), 296 had AD (17.3%), and 20 had other forms of dementia (1.2%). Main Outcome Measure: All-cause mortality. Results: During as many as 10 years of observation (mean [SD], 4.7 [3.0] years), 634 individuals died (37.0%). Compared with people without cognitive impairment, risk of death was increased by about 50% among those with MCI (hazard ratio [95% confidence interval], 1.48 [1.22-1.80]) and was nearly 3-fold greater among those with AD (2.84 [2.29-3.52]). These effects were seen among African Americans and whites and did not differ by race. Among participants with MCI, risk of death increased with more severe cognitive impairment, and this effect did not vary by race. A similar effect was seen among participants with AD, but it was slightly stronger for African Americans vs whites. In the MCI and AD groups, the association of cognitive impairment with survival was stronger for perceptual speed than for other cognitive functions. Conclusion: The presence and severity of MCI and AD are associated with reduced survival among African Americans, and these effects are comparable to those seen among whites.