Memory decline linked to infection exposure

Lessened memory and reasoning function is linked to exposure, not necessarily contraction, of common infections, according to a press release from the American Heart Association.

The study shows that cognitive performance, abstract thinking, planning, reasoning and mental processing decline, along with slower memory, are related to various infections. But the study's authors caution that more evidence is needed to confirm the relation between the two.

Lead researcher Clinton Wright, scientific director of the Evelyn F. McKnight Brain Institute at the University of Miami, was also interested in the correlation because of past studies, published in the journal Stroke. Medical News Today says these studies found a link between a decrease in brain function and an increase in heart disease risk, and that there is a link between increased risk for stroke and Alzheimer's disease and infections.

Wright and colleagues proceeded by taking blood samples from 588 participants in a Northern Manhattan Study. They each took a brain test, and then another five years later. The results showed connections between antibody levels caused by exposure to common infections and deteriorating cognitive performance.

The common infections the researchers studied included Chlamydia pneumoniae (which can lead to pneumonia and bronchitis), Helicobacter pylori (which causes most stomach and duodenal ulcers), and the herpes simplex viruses 1 and 2 (which can cause cold sores).

But the study doesn't actually explain the reasoning behind the link between a drop in cognitive performance and infections, according to Wright, only that there is a connection.

"It could be caused by an immune system response to the infections or the infection itself could result in clinical damage that we're not aware of," he said in a statement.

He also adds that no one knows for sure whether these cognitive effects can be reversed.

"There is no evidence yet that treating these infections is beneficial," he said. "It would be great if treatment prevented these bad outcomes, but we're very far away from having that type of evidence."