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CMV increased Alzheimer’s risk, led to rapid cognitive decline
In a racially diverse population of older adults, cytomegalovirus infection was associated with a higher risk for Alzheimer’s disease and a more rapid rate of mental decline, according to recent findings.
“Human cytomegalovirus (CMV) is prevalent in older adults and has been associated with cardiovascular disease and mortality,” the researchers wrote in The Journal of Infectious Diseases. “Growing literature suggests that CMV is involved in the etiology of Alzheimer’s disease.”
In the study, researchers merged data on 849 participants from three ongoing cohort studies: the Rush Memory and Aging Project (MAP), the Religious Order Study (ROS) and the Minority Aging Research Study (MARS). The three studies have similar designs, recruitment techniques and data collection methods. The researchers selected a subset of black patients (n=210) from all three studies who met the following criteria: availability of blood specimens, absence of dementia at the time of the blood specimen collection, and having undergone at least two evaluations of cognitive decline. They randomly identified a subset of white participants (n=639) from MAP and ROS using the same criteria. The mean age of the participants was 78.6 years, and their mean duration of education was 15.4 years.
The researchers evaluated archived serum samples for antibody responses to CMV and herpes simplex virus type 1. Participants also underwent a clinical assessment for Alzheimer’s disease, conducted by clinicians who were masked to any data gathered before that time. The patients were followed for an average of 5 years. Cox proportional hazard models were used to analyze the association between CMV seropositivity and increased risk for Alzheimer’s disease.
The researchers found that 73.4% of the study participants had serologic evidence of exposure to CMV; 89% were black and 68.2% were white (P<.001). During the follow-up period, 93 individuals in the study cohort developed Alzheimer’s disease.
They also found an association between CMV positivity and increased risk for Alzheimer’s disease (RR=2.15; 95% CI, 1.42-3.27), as well as a more rapid rate of cognitive decline, which was assessed using global measures based on 16 different tests (P=.03). The results were comparable between races in both Alzheimer’s onset and cognitive decline. These findings were independent of HSV-1 seropositivity.
The researchers noted that while these findings did not differ significantly between black and white individuals, race may nevertheless be relevant.
“Despite the lack of a differential effect by race, the results suggest that the overall burden of this disease is greater in black individuals because they are much more likely to be infected with CMV,” the researchers wrote. “In fact, given the well-established racial difference in CMV prevalence and risk of Alzheimer’s disease, the current results reflect a targetable health disparity for potential interventions, such as antiviral medications for CMV, to assess whether intervening on CMV reactivation may reduce risk of Alzheimer’s disease development and cognitive decline.”
Disclosure: The researchers report no relevant financial disclosures.