Relationship of age, education, and occupation with dementia among a community-based sample of African Americans
C. M. Callahan, K. S. Hall, S. L. Hui, B. S. Musick, F. W. Unverzagt and H. C. Hendrie
Department of Medicine, Indiana University School of Medicine, Indianapolis, USA.
OBJECTIVE: To explore the relationship between age, education, and
occupation with dementia among African Americans. DESIGN: Community-based
survey to identify subjects with and without evidence of cognitive
impairment and subsequent diagnostic evaluation of a stratified sample of
these subjects using formal diagnostic criteria for dementia. SETTING:
Urban neighborhoods in Indianapolis, Ind. SUBJECTS: A random sample of 2212
African Americans aged 65 years and older residing in 29 contiguous census
tracts. MEASUREMENTS: Subjects's scores on the Community Screening
Instrument for Dementia (CSI-D), formal diagnostic clinical assessments for
dementia, years of education, rural residence, primary occupation,
self-reported disease, and alcohol and smoking history. Caseness was
defined by four separate criteria: (1) cognitive impairment as defined by
the subject's performance on the CSI-D cognitive scale; (2) cognitive
impairment as defined by the total CSI-D score that included a relative's
assessment of the subject's functional abilities; (3) dementia as defined
by explicit diagnostic criteria; and (4) possible or probable Alzheimer's
disease as defined by explicit diagnostic criteria. RESULTS: The mean age
was 74 years (age range, 65 to 100 years), 65% of subjects were women, the
mean education was 9.6 years (age range, 0 to 16 years), 98% of the
subjects were literate, and 32% reported living in a rural area until age
19 years. Service, domestic, and production occupations accounted for 55.2%
of the subjects' primary occupations with a mean of 25.8 years (range, 1 to
75 years) in the primary occupation. Years of education, rural residence to
age 60 years, and primary occupation were highly correlated. Caseness
defined by any of the four criteria was associated with functional
impairment, but the frequency of impairment increased with increasing
diagnostic specificity. Age, education, and rural residence to age 60 years
were significantly independently associated with caseness for cognitive
impairment, dementia, and Alzheimer's type dementia. White-collar
occupation was independently associated only with caseness for cognitive
impairment. History of stroke was associated with caseness for cognitive
impairment and dementia but not Alzheimer's disease, while history of
smoking was negatively correlated with Alzheimer's disease. CONCLUSIONS:
Education was independently associated with cognitive impairment and
dementia among a representative community-based sample of African Americans
and the association remains significant across a variety of sensitivity
analyses designed to control for measurement and confounding biases. The
potential protective role of education against the development of dementia
among African Americans deserves further evaluation.