Sunday March 24, 2019

A Landmark Study Links Herpes 6 and 7 with Alzheimer’s Disease

The findings also showed multiple points of overlap between virus-host interactions and genes associated with Alzheimer's risk

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For the study, published in the journal Nature, the team engineered a hydrogel that can swell those lymphatic vessels.
For the study, published in the journal Nature, the team engineered a hydrogel that can swell those lymphatic vessels. (IANS)

Scientists have found up to two times higher level of human herpes virus among people with Alzheimer’s disease, suggesting the potential role of the viruses in the development of the progressive brain disorder.

Herpes virus causes contagious sores, most often around the mouth or on the genitals.

The study found unusually increased level of human herpesvirus named human herpesvirus 6A (HHV-6A) and human herpesvirus 7 (HHV-7 ) in the brains of the people with Alzheimer’s than those without the disorder.

“The hypothesis that viruses play a part in brain disease is not new, but this is the first study to provide strong evidence,” said Richard J. Hodes, Director from the US National Institutes of Health.

“Our work identified specific biological networks that offer new testable hypotheses regarding the role of microbial defense and innate immune function in the pathophysiology of Alzheimer’s,” said Joel Dudley from the Institute for Next Generation Healthcare at the Icahn School of Medicine at Mount Sinai.

alzheimers
Patient of Alzheimer’s. Pixabay

The findings also showed multiple points of overlap between virus-host interactions and genes associated with Alzheimer’s risk. Multiple viruses impact the biology of Alzheimer’s disease across domains such as DNA, RNA and proteins.

“If it becomes evident that specific viral species directly contribute to an individual’s risk of developing Alzheimer’s or their rate of progression once diagnosed, then this would offer a new conceptual framework for understanding the emergence and evolution of Alzheimer’s at individual, as well as population, levels,” Dudley explained.

In the study, published in the journal Neuron, the team initially performed RNA sequencing on four brain regions in more than 600 samples of postmortem tissue from people with and without Alzheimer’s to quantify which genes were present in the brain, and whether any were associated with the onset and progression of Alzheimer’s.

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Using different computational approaches, the team uncovered a complex network of unexpected associations, linking specific viruses with different aspects of Alzheimer’s biology.

They examined the influence of each virus on specific genes and proteins in brain cells, and identified associations between specific viruses and amyloid plaques, neurofibrillary tangles, and clinical dementia severity.

Further, they incorporated 800, RNA sequencing samples and observed a persistent increase of HHV-6A and HHV-7 in samples from individuals with Alzheimer’s. (IANS)

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Eye Test May Help in Early Detection of Alzheimer’s Disease

Conversely, in the eyes of 39 people with Alzheimer's disease, that web was less dense and even sparse in places

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In Alzheimer's disease, patients start losing memory. Pixabay

A future non-invasive eye test may allow early detection of Alzheimer’s disease before memory loss kicks in, say a team led by an Indian-origin researcher.

Retina being an extension of the brain, the optical coherence tomography angiography (OCTA) will check patients’ vision as well as brain health, said the study published in the journal Ophthalmology Retina.

The researchers said that loss of blood vessels in retina would reflect changes in the brain, be it for both healthy people or Alzheimer’s patients.

“We know that there are changes that occur in the brain in the small blood vessels in people with Alzheimer’s disease, and because the retina is an extension of the brain, we wanted to investigate whether these changes could be detected,” said lead author Dilraj S. Grewal, ophthalmologist at Duke University.

Using the OCTA that uses light waves that reveal blood flow in every layer of the retina, the researches checked more than 200 people.

A lady suffering from Alzheimer’s. Flickr

They found that in people with healthy brains, microscopic blood vessels form a dense web at the back of the eye inside the retina — as was seen in 133 participants in a control group.

Conversely, in the eyes of 39 people with Alzheimer’s disease, that web was less dense and even sparse in places.

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The OCTA machines, relatively a new noninvasive technology, measures blood vessels that cannot be seen during a regular eye examination.

“It’s possible that these changes in blood vessel density in the retina could mirror what’s going on in the tiny blood vessels in the brain, perhaps before we are able to detect any changes in cognition,” added Sharon Fekrat, ophthalmologist at the Duke University in the US. (IANS)