Link Between Alzheimer’s and Herpes
It has long been speculated that colonization or chronic infection with certain microorganisms can aggravate the risk of developing serious disorders; but did you know some sexually transmitted infections like Herpes Simplex can also play a role in the pathogenesis of Alzheimer’s disease?
Most people think of old age and declining memory, when they hear about Alzheimer’s disease. Can there be a link between cold sores and fading cognition and memories?
Is there a link between Herpes infection and Alzheimer’s disease?
Research conducted in the past years suggested that herpes infection can sometimes double the risk of developing Alzheimer’s disease in affected individuals. There are 2 primary clinical variants of Herpes virus; HSV 1 and HSV 2. HSV-1 is the most frequently reported variant and according to some studies, about 90% of the world’s population is a carrier of HSV-1 virus that is generally contracted in the childhood years.
It is noteworthy that most of the cases remain undiagnosed as most individuals never manifest classic symptoms such as cold sores.
What does clinical research have to say?
According to a study published in 2014, the team of clinical investigators studied a sample of 360 individuals with known diagnosis of Alzheimer’s disease. The control group comprised of 360 subjects with no signs or symptoms of Alzheimer’s disease. As part of the analysis, the team of researchers studied the HSV IgG antibodies samples and concluded that there is no direct correlation between anti HSV antibody levels and occurrence of Alzheimer’s disease.
However, a second set of serological tests that were obtained about 6.6 years and later suggested that there is strong association between diagnosis of Alzheimer’s disease and HSV IgG antibodies.
Another recent editorial piece suggested that besides HSC, certain other viral and bacterial agents (such as Chlamydia) also play a role in the pathogenesis of Alzheimer’s disease. Although, the editorial was rejected due to lack of evidence and controversial findings. Regardless, the team of researcher claim there is enough evidence to explain how viral and bacterial chronic infections can cause Alzheimer’s disease. Here are the two primary theories:
- These microbial agents cause iron dysregulation which may play a role in early onset Alzheimer’s disease
- Longstanding infection with these microbes may elicit a state of systemic inflammation
Another study reported in peer reviewed journal Neuron discussed the presence of HSV viral antibodies in the brain tissue of Alzheimer’s disease patients in high concentrations. Researchers postulated that viral agents specifically involved certain areas of brain that are involved with personality, memory, and cognition such as limbic system. This hypothesis is very important because researchers believe that antiviral drugs can slow down the progression of Alzheimer’s disease by reducing the viral load. Likewise, drugs that modulate the immune system can also play a role in improving the outcome in such patients.
It is not entirely clear what is the direct link between Alzheimer’s disease and Herpes infection, but research in underway and very soon there will be an answer.