Common ailment linked to higher risk of Alzheimer’s disease: ‘Public health priority’

Talk about a sore subject.

New research suggests that a common viral infection lurking in as many as 8 out of 10 Americans could increase the risk of Alzheimer’s disease.

But there’s a glimmer of hope — scientists believe antiviral treatments may help protect infected individuals from developing the memory-robbing illness.

Alzheimer’s, the most common form of dementia, affects around 7.2 million Americans aged 65 and older, according to the Alzheimer’s Association.

While scientists haven’t pinpointed a single cause for the progressive brain disorder, factors like age, genetics, lifestyle choices and underlying health conditions can increase the risk.

A groundbreaking new study published Tuesday has uncovered another factor that may play a key role in the development of Alzheimer’s: a symptomatic infection with the virus behind cold sores, herpes simplex 1 (HSV-1).

Researchers combed through 15 years’ worth of US health records, analyzing data from about 345,000 pairs of patients with and without Alzheimer’s.

As expected, the risk of developing Alzheimer’s rose with age. People with the disease were also 80% more likely to have had an HSV-1 diagnosis. 

Researchers also examined the potential role of other herpes viruses, including HSV-2, varicella zoster and cytomegalovirus. They found that infections with the first two were linked to an increased risk of developing Alzheimer’s.

Herpes infections are incredibly common.

Between 50% and 80% of American adults carry HSV-1 (oral herpes), while HSV-2 (genital herpes) affects 1 in 6 Americans aged 14 to 49, according to Johns Hopkins Medicine.

These viral infections spread through intimate person-to-person contact.

Kissing or oral sex can transmit HSV-1, while HSV-2 is spread through vaginal, anal or oral sex. A mother infected with the virus can also pass it to her baby during childbirth.

“These findings place an even greater emphasis on viewing the prevention of herpes viruses as a public health priority,” the study authors said.

Exactly how HSV-1 and other neurotropic viruses might increase the risk of dementia remains unclear.

However, researchers pointed out that previous studies have shown inflammatory changes in the brain, triggered by the infection, play a crucial role in the development of Alzheimer’s.

For example, inflammation can contribute to the formation and buildup of amyloid plaques and neurofibrillary tangles, hallmark features of the disease. Inflammation can also damage neurons, impairing their function and disrupting communication between brain cells.

But there’s a silver lining: antiviral treatment appears to lower the risk of Alzheimer’s in people with a history of HSV-1 infection.

In the study, among the 2,330 people with a history of HSV-1 infection, 40% used antiherpetic medication after their diagnosis. They were 17% less likely to develop Alzheimer’s than those who didn’t use the treatments.

“While the molecular mechanisms remain to be fully elucidated, these results are indicative of a possible role for antiherpetic therapy in mitigating dementia risk,” the study authors concluded. 

Alzheimer’s is the seventh-leading cause of death among US adults, with the average patient living four to eight years after diagnosis.

A cure hasn’t been identified, but treatments and interventions can help slow the disease’s progression and improve quality of life.

In 2020 alone, Alzheimer’s cost the US an estimated $305 billion — and that figure is expected to rise significantly in the coming decades.

With the number of Americans living with the disease steadily increasing, scientists predict that 13.8 million will have Alzheimer’s by 2050, or 16% of the US population over the age of 65.