Alzheimer's disease and its precursor, mild cognitive impairment, is linked to an increased risk of death among both white and African American older adults, shows a new study.
"Data from two national surveys suggest that life expectancy among patients with Alzheimer's disease may be greater for African Americans than for whites," the authors said.
"However, not all surveys have reported this difference. Furthermore, in these surveys, the diagnosis of Alzheimer's disease is not based on a uniform clinical evaluation but derived from medical records, increasing the likelihood of substantial variation in the quality of diagnostic classifications," they added.
For the study, Robert S. Wilson, Ph.D., and colleagues at Rush University Medical Center, Chicago, examined 1,715 older adults (average age 80.1, 52.5 percent African American) from four adjacent neighborhoods in Chicago.
Each participant had a clinical evaluation that included medical history, a neurological examination and cognitive function testing. Based on these evaluations, an experienced physician diagnosed 296 of the participants with Alzheimer's disease, 597 with mild cognitive impairment and 20 with other forms of dementia, while 802 had no cognitive impairment.
During up to 10 years of follow-up, 634 individuals died including 25.8 percent of those without cognitive impairment, 40.4 percent of those with mild cognitive impairment, 59.1 percent of those with Alzheimer's disease and 60 percent of those with other forms of dementia.
"Compared with people without cognitive impairment, risk of death was increased by about 50 percent among those with mild cognitive impairment and was nearly three-fold greater among those with Alzheimer's disease.
These effects were seen among African Americans and whites and did not differ by race," the authors said.
The study is published in the June issue of Archives of Neurology, one of the JAMA/Archives journals.