No reason to suspect that COVID smell loss leads to dementia

A recent article, which has not been peer reviewed, suggests a relationship between Covid-19 related smell loss and increased likelihood of neurodegenerative changes leading to Alzheimers. This article has raised many questions on the AbScent platforms.

The author stated: “We saw pretty early on that some individuals had changes in the brain, or changes in cognition, and loss of sense of smell or taste, which indicates there’s a connection to the brain.”

Different patterns of smell loss

AbScent Trustee Mr Simon Gane, Royal National Ear, Nose and Throat and Eastman Dental Hospitals, University College London Hospital, commented “We know that most of the patterns of smell loss in post-infectious olfactory dysfunction are very different to those in degenerative disease. These are different processes and there is no reason to suspect that Covid smell loss leads to dementia.”

Katie Whitcroft, ENT and author on the subject of brain changes and olfactory dysfunction, commented “We know that there is a link between smell loss and cognitive decline, though most of the data we have is from older patients with smell loss of unknown origin. There are many underlying causes of smell loss, which cause different patterns of impairment. It isn’t clear yet whether these are interchangeable with regards to future cognitive health.

“Don’t panic”

“This new data is interesting, but the conclusions are limited by lack of cognitive testing prior to Covid-19 infection. We need more large-scale work tracking smell and cognition in people before and after Covid-19 and other viral infections. If you lost your sense of smell after Covid-19, don’t panic – it doesn’t necessarily mean you will develop cognitive impairment – cognitive health is affected by many different factors and there are positive steps that can be taken, such as exercising. There is also good evidence that smell training can help people regain their sense of smell, and it may also help to improve cognition.”AbScent feels that the association between Covid-19 related smell impairments and a tendency to cognitive impairment should be viewed with considerable caution until more evidence is available. 

While we await more evidence in this area, smell training and the health of the brain were also addressed in the above mentioned article: “Our best current tool to fight degeneration of olfactory and other parts of the cerebral cortex may be olfactory and environmental enrichment – smelling multiple familiar non-toxic odorants daily in a long therapeutic course (smell training) for olfactory function, plus physical exercise and cognitive training for global brain health.” 

While it is true that Covid can affect the brain, the evidence suggests that the brain’s innate plasticity means that things can change and improve over time. 

Article on NBC platform

August 02, 2022