The mean age of the cohort was 75.6 years (standard deviation 5.9); 68.9 percent of the subjects were women. Forty-five percent of the subjects were Hispanic, and 32 percent were Black.
The prevalence of diabetes was 9.6 percent in Whites, 21.2 percent in Blacks, and 24.1 percent in Hispanics.
There were 213 incident cases of dementia in the cohort. Of these, 157 cases (74 percent) were due to Alzheimer’s disease, 36 cases (17 percent) were due to stroke, and 20 cases (9 percent) were due to other causes.
The incidence of dementia was 1.4 per 1,000 person-years in Whites (33 cases: 23 Alzheimer’s disease, four stroke-associated dementia, and six other), 2.4 per 1,000 person-years in Blacks (80 cases: 62 Alzheimer’s disease, 14 stroke-associated dementia, and four other), and 2.3 per 1,000 person-years in Hispanics (100 cases: 72 Alzheimer’s disease, 18 stroke-associated dementia, and 10 other).
The hazard ratio for nondementia cognitive impairment without stroke in persons with diabetes, as compared with persons without diabetes, was 1.3 (95 percent CI: 0.8, 1.9). The hazard ratio for nondementia cognitive impairment with stroke in relation to diabetes was 1.6 (95 percent CI: 0.6, 4.4) (table 2). Persons with nondementia cognitive impairment have an increased risk of developing Alzheimer’s disease compared with persons without nondementia cognitive impairment (40); therefore, we conducted an analysis examining the relation between diabetes and a composite outcome of Alzheimer’s disease and nondementia cognitive impairment (without stroke). The hazard ratio for this composite outcome in relation to diabetes, as compared with the absence of diabetes, was 1.6 (95 percent CI: 1.2, 2.1).
http://aje.oxfordjournals.org/content/154/7/635.full
Table 1 shows a comparison of characteristics between all subjects in the sample and subjects with Alzheimer’s disease, stroke-associated dementia, nondementia cognitive impairment without stroke, and nondementia cognitive impairment with stroke. Persons with Alzheimer’s disease were older, had fewer years of education, had a higher proportion of Blacks, and had a higher prevalence of heart disease than persons without Alzheimer’s disease.
Persons with stroke-associated dementia were older and had a higher prevalence of diabetes, a higher level of low density lipoprotein cholesterol, a higher prevalence of hypertension, and a higher prevalence of heart disease than persons without stroke-associated dementia.
After the exclusion of 174 cases of nondementia cognitive impairment at baseline, there were 1,088 persons left for the analysis of nondementia cognitive impairment.
Persons with nondementia cognitive impairment without stroke were older and had fewer years of education, a higher proportion of ever smokers, and a higher proportion of Hispanics than persons without it.
Persons with nondementia cognitive impairment with stroke had a higher prevalence of hypertension and heart disease than persons without it.
