Some Chronic Viral Infections Could Contribute to Cognitive Decline With Aging

Certain chronic viral infections could contribute to subtle cognitive deterioration in apparently healthy older adults, according to a study led by researchers from the University of Pittsburgh School of Medicine and Johns Hopkins University that was recently published in the journal Alzheimer's Disease and Associated Disorders.

Many cross-sectional studies, which capture information from a single time point, have suggested a link between exposure to cytomegalovirus (CMV) and herpes simplex viruses (HSV) 1 and 2, as well as the protozoa Toxoplasma gondii and decreased cognitive functioning, says lead investigator Vishwajit Nimgaonkar, MD, professor of psychiatry at Pitt School of Medicine.

"Our study is one of the few to assess viral exposure and cognitive functioning measures over a period of time in a group of older adults," he adds. "It's possible that these viruses, which can linger in the body long after acute infection, are triggering some neurotoxic effects."

The researchers looked for signs of viral exposures in blood samples that were collected during the "Monongahela-Youghiogheny Healthy Aging Team" (MYHAT) study, in which more than 1,000 participants 65 years and older were evaluated annually for five years to investigate cognitive change over time.

They found CMV, HSV-2 or toxoplasma exposure is associated with different aspects of cognitive decline in older people that could help explain what is often considered to be age-related decline.

"This is important from a public health perspective, as these infections are very common and several options for prevention and treatment are available," notes senior investigator Mary Ganguli, MD, MPH, professor of psychiatry at Pitt. "As we learn more about the role that infectious agents play in the brain, we might develop new prevention strategies for cognitive impairment."

Now, the researchers are trying to determine if there are subgroups of people whose brains are more vulnerable to the effects of chronic viral infection.

In addition to Robert H. Yolken, MD, PhD, of Johns Hopkins University, the team included Tianxiu Wang, MS, Ho Chang Chung-Chou, PhD, Lora McClain, BS, Eric McDade, DO, and Beth E. Snitz, PhD, all of Pitt.

The project was funded by National Institutes of Health grants AG02365, AG044395 and AG020677 from the National Institute on Aging and MH09375 from the National Institute of Mental Health; and the Stanley Medical Research Institute.

Source: University of Pittsburgh School of Medicine