The researchers used a test called infectious burden (IB) on blood samples from 1,625 participants in the multi-ethnic Northern Manhattan Study; the average age of participants was 69. IB measures exposure to three viruses (herpes simplex types 1 and 2 and cytomegalovirus) and two bacteria (Chlamydia pneumonia and Helicobacter pylori).
The subjects were given a cognitive assessment, the Mini-Mental State Exam (MMSE). Those who had higher IB scores had a 25 percent higher risk of scoring more poorly on the MMSE.
“The link was strongest among women, those with lower socioeconomic status, and—most notably—those who did not exercise,” said lead author Mira Katan, MD, postdoctoral fellow at the Neurological Institute at Columbia University Medical Center.
As the population ages, clinicians will have an ever greater need for ways to determine risk of cognitive loss. The link between elevated IB and cognitive loss could provide one such tool.
“Infectious burden and cognitive decline” was published in the March 26, 2013, print issue of Neurology, the medical journal of the American Academy of Neurology.