Cold Sores, Ulcers and...Dementia?

Cognition problems associated with common viruses and bacteria in study

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) A cold sore or a slight respiratory infection is just that, right?  An uncomfortable health issue that clears up in a few days? But it may be more complicated than that.

A new study found a possible association between common viral and bacterial infections and problems with mental cognition.

For the study, researchers examined the presence of some common infectious agents and the presence of cognitive troubles in older adults.

Results showed that higher infection levels in the blood were associated with a higher likelihood of cognitive troubles. 

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Researchers led by Mira Katan, MD, of the Columbia University Medical Center in New York, studied 1,625 people who lived in Manhattan. 

All participants were over the age of 40 and had an average age of 69. The group was 58 percent Hispanic and 65 percent women.

Blood samples were taken to test for several common infections, including herpes simplex type 1 (which causes cold sores) and type 2 (which affects the genital area), chlamydia pneumoniae (an infection affecting the respiratory system) and Helicobacter pylori (bacteria affecting the stomach).

Infectious burden (IB) index was determined for each patient. This index is a measure of a person’s exposure to these infectious agents.

Cognition was then measured using the Mini-Mental State Examination test, and later in follow-ups using the Telephone Interview for Cognitive Status. These follow-up interviews were completed annually for an average of eight years.

When the data was analyzed, researchers found that people with higher IB indexes fared worse on the cognition tests. However, researchers found no connection between IB index and changes in memory and thinking abilities.

It is thought that the connection may be due to the inflammation caused by these viral and bacterial infections. 

“It may be that chronic infection due to these pathogens contributes to the overall inflammatory milieu and, together with other risk factors, leads to atherosclerosis, subclinical stroke, and dementia,” the researchers wrote.

“Inflammation in brain vessels has been postulated to play an important role in both vascular dementia and Alzheimer’s disease,” they wrote.

The researchers did find differences in the results when they adjusted for several factors. 

“In general, we found that the magnitude of effects of IB was greater among women, those with lower socioeconomic status (lower levels of education and health insurance), and the physically inactive,” the researchers wrote. “The association was most prominently modified by participants’ physical activity levels.”

This physical activity factor will need to be explored more directly, and further research is needed to confirm and understand a potential connection between these common viruses and cognition issues.

However, if confirmed, it could mean that preventing these viruses early on could help reduce mental decline later in life.

The study was published in the journal Neurology on March 26. Funding was provided by the National Institutes of Health (NIH) and National Institutes of Neurological Disorders and Stroke (NINDS), the Swiss National Science Foundation and the Fondation Leducq.

Reviewed by: 
Review Date: 
March 25, 2013
Last Updated:
August 16, 2013