Cytomegalovirus infection and risk of Alzheimer disease in older black and white individuals.

Background: Human cytomegalovirus (CMV) is prevalent in older adults and has been implicated in many chronic diseases of aging. This study investigated the relation between CMV and the risk of Alzheimer disease (AD).

Methods: Data come from 3 cohort studies that included 849 participants (mean age [±SD], 78.6 ± 7.2 years; mean education duration [±SD], 15.4 ± 3.3 years; 25% black).

Results: A solid-phase enzyme-linked immunosorbent assay was used for detecting type-specific immunoglobulin G antibody responses to CMV and herpes simplex virus type 1 (HSV-1) measured in archived serum samples. Of 849 participants, 73.4% had serologic evidence of exposure to CMV (89.0% black and 68.2% white; P < .001). During an average of 5.0 years of follow-up, 93 persons developed AD. CMV seropositivity was associated with an increased risk of AD (relative risk, 2.15; 95% confidence interval, 1.42-3.27) and a faster rate of decline in global cognition (estimate [±standard error], -0.02 ± 0.01; P = .03) in models that controlled for age, sex, education duration, race, vascular risk factors, vascular diseases, and apolipoprotein ε4 level. Results were similar in black and white individuals for both incident AD and change in cognitive function and were independent of HSV-1 status.

Conclusions: These results suggest that CMV infection is associated with an increased risk of AD and a faster rate of cognitive decline in older diverse populations.