The associations of Lewy bodies (LBs) with olfactory dysfunction, parkinsonism, and higher odds of dementia were assessed in Black and White community-dwelling elders and racial differences in these associations were tested.
Black decedents (n = 81) were matched 2-to-1 by age, sex, years of education, and follow-up time in the study with White decedents (n = 154) from 4 longitudinal studies of dementia and aging. Participants underwent uniform clinical examination and cognitive, motor, and olfactory testing. LBs were detected in 7 brain regions by α-synuclein immunohistochemistry and racial differences in their association with olfaction, parkinsonism, and odds of dementia were determined using regression analyses.
The mean scores of the odor test, global parkinsonism signs, and global cognition were lower in Black than White decedents; the frequency of dementia was similar in both groups. The frequency of LBs was similar in Black and White decedents (~25%), as was the frequency of LBs in individual brain regions, while the mean LB counts/mm2 were similar in all regions except the cingulate cortex, which showed higher mean LB counts in Black decedents. In regression analyses, LBs were associated with impaired olfaction (–2.23, 95% confidence interval [CI] –3.45 to –1.01) and higher odds of dementia (odds ratio 3.0, 95% CI 1.10–8.17) in both racial groups; an association with parkinsonism was stronger in Black than White decedents.
The frequency, distribution, and clinical manifestations of LBs are similar in Black and White elders.