Study: Some Infections Up Dementia Risk for Patients With Heart Disease

Infection by several common viruses appears to significantly increase the risk of dementia in the elderly with cardiovascular disease, according to a Finnish study.

As reported in the Aug. 15 rapid access issue of Stroke, the study involved 383 cardiovascular disease patients who were tested for antibodies to the viruses herpes simplex type 1, herpes simplex type 2 and cytomegalovirus. All patients had atherosclerosis or hardening of the arteries.

The presence of antibodies to these viruses indicates a current or previous infection. The researchers selected these three viruses because several studies have suggested a link between each of them and dementia.

Herpes simplex type 1 causes cold sores, while herpes simplex type 2 is a sexually transmitted disease. Cytomegalovirus infects between 50 percent and 85 percent of U.S. adults by age 40, but causes few symptoms and no long-term health consequences in most healthy persons.

People with antibodies to two of the viruses had a 1.8 times greater risk of dementia than those infected by none or one of the viruses. Those infected by all three viruses had a 2.3 times higher risk of dementia.

"Inflammation has been implicated in dementia, and viral infections could be a triggering factor," said study author Dr. Timo Strandberg, of the University of Helsinki. "Our findings should be tested in other studies, but if these viruses are involved, there are existing therapies such as vaccination and antiviral drugs that could be used to prevent or treat dementia."

Researchers also tested patients for infection by the bacteria chlamydia pneumoniae, which causes respiratory diseases, and mycoplasma pneumoniae, which causes walking pneumonia.

Contrary to past studies that associated these bacteria with atherosclerosis and late onset dementia, including Alzheimer's, Strandberg's team found no link between them and a patient's decline in cognitive powers.

Other sources: American Stroke Association