While several works suggested a link between the herpes virus and an increased likelihood of developing Alzheimer’s disease, a new study contradicts this theory.
With 50 million people affected, Alzheimer’s disease is the main cause of dementia in the world. This neurodegenerative affliction is characterized by progressive loss of memory, cognitive abilities and verbal skills. Today, while there are medications available to temporarily relieve symptoms and slow the rate of decline, the disease remains incurable and a real public health issue. This is why many researchers are working to try to better understand its mechanisms. And, while work has recently made the link between the herpes virus and Alzheimer’s, a new American study contradicts this theory. The results were published on Wednesday December 18 in the journal Neuron.
In 2018, researchers found increased levels of human herpesvirus 6A (HHV-6A) and human herpesvirus 7 (HHV-7) in the postmortem brain tissue of over 1,000 Alzheimer’s patients. This presence therefore indicated that the active infections were linked to Alzheimer’s disease and many studies began to be carried out on the subject.
However, when researchers from the researcher at Baylor College of Medicine (Texas, USA) reanalyzed the datasets from the 2018 study using rigorous filtering and four commonly used statistical tools, they did not find found no link between the abundance of herpes virus DNA or RNA and the likelihood of Alzheimer’s disease.
Identify treatment strategies
“The more high-throughput ‘omics’ technologies, which include those for genomics, proteomics, metabolomics and others, become affordable and readily available, the more there is a growing trend towards ‘big data’ in the basic biomedical research. In these situations, given the massive amounts of data that must be mined and extracted in a short time, researchers may be tempted to rely solely on p-values to interpret results and come to conclusions,” says Dr. Zhandong Liu , who conducted the study.
The latter “highlights one of the potential pitfalls of overreliance on p-values. Although p-values are a very valuable statistical parameter, they cannot be used as a stand-alone measure of statistical correlation — datasets from high-throughput procedures still need to be carefully plotted to visualize the data distribution.” adds Dr. Hyun-Hwan Jeong, who participated in the research. “Datasets must also be used in conjunction with precisely calculated p-values to make gene-disease associations that are statistically correct and biologically meaningful,” he continues.
Zhandong Liu concludes, “Our goal in pursuing and publishing this study was to generate tools and guidelines for the analysis of big data, so that the scientific community can identify treatment strategies that are likely to benefit patients.”
Worldwide, it is estimated that more than 85% of adults are infected with HHV-6
In France, Alzheimer’s disease affects approximately one million people. According to Foundation for medical research, 225,000 new cases are diagnosed each year. In 2040, 2.1 million patients over 65 should be affected.
Regarding the human herpesvirus, it includes six categories. HHV-6 (there are two variants, HHV-6A and HHV-6B) is very common worldwide as it is estimated that over 85% of adults are infected worldwide. HHV-6 infection most commonly results in fever with sudden exanthema (exantheme subitum), a skin rash better known as roseola and reported in 10% of cases. The virus is also associated with severe complications such as encephalitis, lymphadenopathy, myocarditis and myelosuppression. According to some research, HHV-6 is also linked to the development of multiple sclerosis. As for HHV-7, it remains to this day relatively unknown. Also, to date, no specific pathology has yet been officially attributed to it.
.