Common infections are associated with reduced performance on a test of global function, according to researchers from Johns Hopkins University.
The investigators compared associations between positive antibody tests for herpes simplex virus, cytomegalovirus (CMV), Epstein-Barr virus (EBV), varicella zoster virus (VZV) and Toxoplasma gondii with performance on the Mini-Mental State Examination (a standard test of cognition) and delayed verbal recall performance. Study participants included 575 adults aged 41 to 97 years old from the Baltimore Epidemiologic Catchment Area Study.
The presence of antibodies for cytomegalovirus or herpes simplex virus and evidence for having had multiple common infections were associated with poorer scores on the Mini-Mental State Examination, Alexandra M. Wennberg, of the Karolinska Institutet in Sweden and colleagues reported.
The new results add to growing evidence that some common infections are tied to cognitive impairment, the authors wrote.
As people age, they are not only exposed to more infectious agents, but become less able to fight them off. HSV-1 seropositivity prevalence, for example, increases from about 50% in younger adults to 90% in people aged 70 years and older. Overall, most older adults carry evidence of having been infected by several of the agents studied, the researchers noted.
The theory that common infections are linked to cognitive decline is controversial and has languished on the fringe of dementia research, according to senior author Adam Spira, PhD. “But due to findings like the ones from this study, it’s starting to get more mainstream attention,” he added.
“To our knowledge, this kind of additive effect of multiple infections on performance on a cognitive test has not been shown before,” he and his colleagues noted.
The study was published in the journal Alzheimer’s & Dementia.
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