By John Salak –
Most people probably think that developing a common infection may be a bit unpleasant but ultimately harmless. Perhaps they need to think again, especially when it comes to middle-aged and older adults.
New research from Johns Hopkins University now warns these infections are connected to poor cognitive performance for mature adults. They may even increase the risk of Alzheimer’s disease and other dementias.
The university’s results were developed after examining the antibody levels to five common pathogens in 575 adults, ages 41 to 97. The adults were recruited from East Baltimore in 1981 as part of the Epidemiologic Catchment Area Study started that year by the National Institute of Mental Health.
Those involved had their blood tested and took cognitive tests during the study. The tests specifically examined whether the participants had developed infections for herpes viruses, cytomegalovirus, chickenpox and shingles viruses, Epstein-Barr virus and the parasite Toxoplasma gondii, which is often spread to humans from cat feces or from eating undercooked meat.
The examination found that the worst cognitive performance occurred among those with elevated antibodies to either herpes simplex virus type 1 or cytomegalovirus. Participants in general with a higher number of positive antibody tests tended to miss more items on the cognition tests.
“The idea that common infections could contribute to cognitive decline and perhaps Alzheimer’s disease risk was once on the fringe and remains controversial, but due to findings like the ones from this study, it’s starting to get more mainstream attention,” reported senior author Adam Spira, Ph.D., a core faculty member of the Johns Hopkins Center on Aging and Health.
“After accounting for participants’ age, sex, race and the largest genetic risk factor for Alzheimer’s disease, the data in our study showed that a greater number of positive antibody tests related to five different infections was associated with poorer cognitive performance. To our knowledge, this kind of additive effect of multiple infections on performance on a cognitive test has not been shown before.”
The cause of Alzheimer’s disease remains unclear, although the Johns Hopkins team noted that prior research had connected infections, such as herpes simplex virus type 1 and cytomegalovirus, to increased Alzheimer’s risk. The team stressed that while its research supports the notion that common infections increase cognitive risks for older adults, more research is essential to determine why this association occurs and whether these associated risks can be reduced.
The impact of Alzheimer’s in the U.S. and worldwide is not only staggering, it is growing. The Alzheimer’s Association reports that there are more than six million Americans currently living with the disease and that this number is likely to double to 13 million by 2050.
Worldwide more than 55 million people are confronting the disease and by 2030 the level is expected to increase to 78 million.
There are no foolproof cures, although a report out of New Zealand offers promise that a new online tool can help identify at-risk individuals early enough to help offset the disease before it takes hold.
A team from the University of New South Wales-Sydney has developed the online risk assessment tool known as CogDrisk, which is currently in trials. The process takes approximately 20 minutes to complete and provides a personalized dementia risk report that patients can discuss with their doctor. Early indications are promising.
“There’s lots of information about the risk factors for dementia in the academic literature,” noted UNSW Professor Kaarin Anstey. “But there’s a gap between just knowing the risks and actually being able to assess whether or not you have the risk and then knowing what to do about it. CogDrisk was developed to address this.”
With dementia treatments limited if nonexistent, the work at UNSW supports the growing calls to focus on early detection and prevention until treatments are available.
“Prevention is now recognized by the World Health Organization as one of the key areas of research. Alzheimer’s Disease International and most of the National Dementia action plans include dementia risk reduction,” Anstey explained.
The New Zealand team developed a systematic review of the various dementia risk factors over several years to build CogDrisk. These included insufficient physical activity, obesity and high blood pressure in middle age, smoking and poor diet.
“Our statistical analysis shows it’s a very robust and generalizable tool,” Anstey said. “It works across different countries and different data sets. And it’s also quite comprehensive, it includes a lot of the newer risk factors that weren’t previously included.”
Identifying risk, unfortunately, isn’t the only obstacle in developing an early warning tool. It must take in other issues and be relatively simple to use if it is to be effective.
“Not only are there lots of risk factors, but dementia itself is very complex, and GPs are very busy,” he explained. “So we’re trying to develop ways of making it easier for the public and GPs to get the right information. And we’re also looking at developing a short form of the tool.”