Viruses Can Cause Inflammation and Damage the Olfactory System’s Synapses, Potentially Hastening the Onset of Alzheimer’s Disease

According to a recent study, viruses can inflame and damage connections between the olfactory system, which regulates the sense of smell, and the portion of the brain connected with memory and learning, potentially hastening the onset of Alzheimer's disease.

Olfactory viral inflammation associated with Alzheimer's disease

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The results, published in the journal Neurobiology of Aging on Tuesday, might lead to novel medicines that identify Alzheimer's disease (AD) early while also shedding light on the role that viruses and the olfactory system play in the disease's progression, as per ScienceDaily.

"We know that losing one's sense of smell is one of the early indications of Alzheimer's disease," said the study's lead author, Andrew Bubak, PhD, assistant research professor in the division of neurology at the University of Colorado School of Medicine.

Bubak's team concentrated on the olfactory tract, olfactory bulb, and the hippocampus, the part of the brain responsible for memory and learning.

They looked at messenger RNA in the brain tissue of six Colombians with Familial Alzheimer's disease (FAD) and tissue from a control group that didn't have AD.

They discovered signs of viral infection in the FAD group's olfactory bulbs, as well as inflammation in the olfactory tract, which transports information to the hippocampus.

In addition, they detected abnormal myelination in the olfactory tract.

Myelin is a fatty layer that surrounds neurons and permits electrical impulses to flow fast and smoothly.

Signaling stops if it is destroyed.

"These findings suggest the hypothesis that viral infection, accompanying inflammation, and dysregulation of olfactory system myelination may alter hippocampus function, leading to the acceleration of FAD development," according to the study.

The senior author of the study, Diego Restrepo, Ph.D., professor of cell and developmental biology at the University of Colorado School of Medicine, stated that viruses have long been suspected of playing a role in cognition issues.

Some research has linked the SARS-CoV-2 virus, which causes COVID-19, to dementia.

The virus, which spreads through the nose, causes some afflicted people to lose their sense of smell.

Simultaneously, the varicella-zoster virus, which causes shingles, and the herpes simplex virus can deposit amyloid beta, a protein required for the development of Alzheimer's disease, in the olfactory bulb.

Even after symptoms have subsided, viruses can live on for years.

Bubak and Restrepo believe that inflammation and amyloid deposits in the olfactory system are interfering with communication with the hippocampus.

They think that without sensory information, the hippocampus begins to atrophy.

Also Read: Scientists Found a Blood Protein Responsible for the Pathogenesis of Alzheimer's Disease

Alzheimer's and Memory Disorders Treatment Center

Alzheimer's disease is distressing since there is no treatment and the typical life span after diagnosis is 10 years.

People suffering from Alzheimer's disease struggle to accept and plan for the inevitability of losing their most valuable assets: the ideas, memories, connections, and personality qualities that constitute who they are, as per John Hopkins Medicine.

The Memory and Alzheimer's Treatment Center, which opened its doors in 2008, brings together psychiatry, neurology, and geriatric medicine to educate, treat, and assist patients and carers.

They assist patients in improving their quality of life by enhancing functioning, controlling symptoms, and treating co-morbidities.

According to Esther Oh, associate professor of medicine, assistant professor of pathology, and associate head of the center, the facility receives over 3,000 appointments each year, with approximately 30% coming from out of state.

In reality, efforts to create medications to prevent or cure this deadly illness have been fruitless.

Despite the fact that almost a hundred treatments have been explored, the few drugs now on the market can only relieve behavioral and cognitive symptoms, not cure or reverse the disease's progression.

Alzheimer's disease is the most prevalent cause of dementia, accounting for over 70% of all cases and affecting approximately 5.7 million Americans.

According to the Alzheimer's Association, because the population is aging, that figure might reach 14 million by 2050.

The Alzheimer's Association further noted that the federal government, recognizing the psychological and financial toll of Alzheimer's disease, has more than doubled research funding since 2011, to $2.3 billion in 2019.