Loss of smell is a warning sign of Alzheimer’s disease. What would you do if you lost your sense of smell with Covid?

One of Covid’s strange symptoms — loss of sense of smell — symptoms that were considered warning signs of dementia long before the pandemic.

A big question now for researchers is whether Covid-related loss of smell may also be linked to cognitive decline. 5% of Covid patients worldwide — about 27 million people — report loss of their sense of smell lasting six months or more.

New preliminary findings released on Sunday Alzheimer’s Association International Conference San Diego suggests there may be a link, but experts warn more research is needed.

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Previous research Some Covid patients have been found to develop cognitive deficits after infection. We found that loss of the sense of smell may be a stronger predictor of cognitive decline.

“Our data strongly suggest that adults over the age of 60 are more vulnerable to post-Covid cognitive impairment if they had an olfactory impairment, regardless of Covid severity,” he said. Study co-author Professor Gabriela Gonzalez Alemán said. The Catholic University of Católica Argentina in Buenos Aires added that it is too early to tell whether the cognitive impairment is permanent.

In this study, 766 adults aged 55 to 95 years were followed for 1 year after infection. Nearly 90% had confirmed Covid cases, and all completed routine physical, cognitive and neuropsychiatric examinations over the course of a year.

Two-thirds of those infected had some form of cognitive impairment at the end of the year. In half the participants the disability was severe.

The researchers did not have hard data on the cognitive status of the patients before Covid infection to compare with the final findings, but they asked the participants’ families about their cognitive function before the infection. I asked Cognitive deficits evident prior to study.

According to Jonas Olofsson, professor of psychology at Stockholm University, Smell and dementia risk —and although I wasn’t involved in the new research, smell loss is a well-established precursor to cognitive decline. He said there was.

“The question is whether these two studies intersect,” Olofsson said. “This study is very intriguing, but the information I’ve seen so far doesn’t allow me to draw any strong conclusions.”

The connection between smell and the brain

According to Dr. Claire Sexton, senior director of scientific programs and outreach at the Alzheimer’s Association, “Loss of smell signals an inflammatory response in the brain.”

“We know Inflammation is part of the neurodegenerative process in diseases such as Alzheimer’s diseasesaid Sexton. But we need to dig deeper into how they are connected. ”

Another study unrelated to Covid was published last Thursday in the journal Alzheimer’s disease and dementia Probe that connection further. Researchers at the University of Chicago found that not only does a decline in the sense of smell over time predict cognitive loss, but loss of the sense of smell may be a warning sign of Alzheimer’s disease and structural changes in brain regions important for Alzheimer’s disease. I discovered that I have dementia.

Using data from the Memory and Aging Project at Rush University, researchers tracked smell loss in 515 older adults over 22 years.they also measured gray mass in the part of the brain associated with dementia and the part associated with smell.

They found that people whose sense of smell declined rapidly over time had less gray matter in both of these areas of the brain. This is not the case, suggesting that olfaction has a unique connection to cognition in terms of structural differences.

“Changes in olfactory function over time can not only predict the development of dementia, but can also predict the size of important brain regions,” said the study leader, director of rhinology and allergy at UChicago Medicine. said Dr. Jayant Pinto,

Odors that are “important” for cognition

Covid isn’t the first virus to cause smell loss, but virus-related smell loss occurred infrequently before the pandemic, Pinto said. Only recently has it become possible to conduct large-scale studies on how

“The sense of smell is very important for cognition, especially for the brain to process information about the environment.

But whether Covid-related loss of smell could be the cause cognitive decline remain vague.

“That’s an open question: Does damage to the olfactory system by SARS-CoV-2 cause problems not only in the olfactory system, but also in the brain itself?” Pinto said.

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According to Olofsson, the olfactory system—the part of the brain associated with smell, including the olfactory bulb, the part of the brain that processes smells—connects to the part of the brain that processes memory. It’s possible that the new coronavirus could destroy the olfactory bulb and worsen the brain around it, but that’s unlikely, Olofsson said.

“There are many other ways to connect the two things. The cause could be a medical condition unrelated to the effects of Covid,” he said.

Or, Olofsson said, Covid could simply amplify pre-existing loss of smell and cognitive decline that we were unaware of prior to infection. Patients may already be experiencing some degree of cognitive decline when infected with Covid. Or maybe you already have a slight sense of smell, making you more susceptible to Covid-related loss of sense of smell.

“It’s possible that even with atrophy the olfactory function was preserved, but when Covid hit, it was wiped out,” he said.

If it turns out that Covid’s loss of smell can cause cognitive impairment, understanding the relationship could help doctors intervene early on smell loss and prevent cognitive decline in people at high risk. There is a possibility.

“We are dealing with a virus epidemic that will never go away,” Pardo said. “If we learn more about how to quickly restore our sense of smell, we may be able to minimize the damage that loss of smell can cause to cognitive impairment in susceptible people.”

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