Background: Vascular risk factors have been associated with risk of cognitive decline, with increasing evidence that midlife exposure to these risk factors may be most important in conferring late-life risk of cognitive impairment. We explored associations between vascular risk factors measured in midlife and the development of dementia over 25 years in the biracial Atherosclerosis Risk in Communities (ARIC) cohort.
Methods: Participants in the ARIC study were recruited from four U.S. communities in 1987-1989, at ages 45-64, with four additional in-person visits, surveillance for hospitalizations, annual phone calls, and repeated cognitive evaluations over a 25-year period. In 2011-2013, ARIC participants were seen for the ARIC Neurocognitive Study (ARIC-NCS), and underwent a detailed neurocognitive battery and informant interviews. Through adjudicated review, dementia cases were defined. Additional dementia cases were identified through the telephone interview for cognitive status (TICS) or informant interview for those participants not attending ARIC-NCS; or by a prior dementia ICD-9 code during a hospitalization.
Results: Of 15,744 participants in the cohort, 1516 cases of dementia were identified, of whom over one third were among black participants. Risk of dementia was highest in individuals of black race, with less than a high school education, older age, APOE ε4 carriage, and who, at ARIC baseline, had hypertension, diabetes, or were current smokers (table). APOE ε4 and smoking were each stronger risk factors for dementia in whites than in blacks.
Discussion: Vascular risk factors measured in midlife are associated with increased risk of dementia in this biracial cohort, in black and white participants. The risk associated with diabetes nears the increased risk associated with having an APOE ε4 allele. Further studies are needed to evaluate the mechanism of and opportunities for prevention of the cognitive sequelae of these risk factors in midlife.