Loss of Smell, Poorer Physical Fitness Associated With Cognitive Impairment Following COVID-19 Infection

Research presented at the Alzheimer’s Association International Conference (AAIC) 2021 found associations between COVID-19 and persistent cognitive deficits, including the pathology and symptoms of Alzheimer disease. According to the investigators, it was also found that cognitive impairment correlates with persistent loss of smell in recovered COVID-19 patients.

“These new data point to disturbing trends showing COVID-19 infections leading to lasting cognitive impairment and even Alzheimer’s symptoms,” said Heather M. Snyder, PhD, Alzheimer’s Association vice president of medical and scientific relations, in a press release. “With more than 180 million cases and nearly 4 million deaths worldwide, COVID-19 has devastated the entire world. It is imperative that we continue to study what this virus is doing to our body and brain. The Alzheimer’s Association and its partners are leading, but more research is needed.”

In addition to the respiratory and gastrointestinal complications associated with COVID-19, many patients experience short- and/or long-term neuropsychiatric symptoms, including loss of smell and taste, and cognitive and attention deficits, commonly referred to as “brain fog.”

For certain patients, these neurological symptoms are persistent. Investigators are currently working to understand the mechanisms behind the cognitive dysfunction caused by SARS-CoV-2 and what it could mean for long-term cognitive health in these patients.

Investigators evaluated the cognition and olfactory senses of a cohort of nearly 300 older adults who had COVID-19. Participants were observed between 3 and 6 months following COVID-19 infection.

More than half of the study participants had persistent problems with forgetfulness. Further, 1 in 4 patients had additional problems with cognition, including language and executive dysfunction. These difficulties were associated with persistent problems in smell, regardless of the severity of the original COVID-19 symptoms.

“We’re starting to see clear connections between COVID-19 and problems with cognition months after infection,” said Gabriel de Erausquin, MD, PhD, MSc, in the release. “It’s imperative we continue to study this population, and others around the world, for a longer period of time to further understand the long-term neurological impacts of COVID-19.”

It was also found by a separate study that individuals who recovered from COVID-19 and who experienced cognitive decline were more likely to be in poor physical condition and have lower oxygen saturation. The investigators analyzed cognitive impairment and related health measures in 32 previously hospitalized patients who had mild to moderate COVID-19 2 months after discharge from the hospital.

Worse cognitive test scores for these patients were associated with higher age, waist circumference, and waist-to-hip ratio, according to the investigators. Further, after adjusting for age and sex, worse memory and thinking scores were independently associated with lower levels of oxygen saturation during the 6-minute walk test, a metric commonly used to assess the functional capacity of people with cardiopulmonary disease.

“A brain deprived of oxygen is not healthy, and persistent deprivation may very well contribute to cognitive difficulties,” said George Vavougios, MD, PhD, postdoctoral researcher for the University of Thessaly, in the release. “These data suggest some common biological mechanisms between COVID-19’s dyscognitive spectrum and post-COVID-19 fatigue that have been anecdotally reported over the last several months.”

REFERENCE

COVID-19 associated with long-term cognitive dysfunction, acceleration of alzheimer’s symptoms [news release]. AAIC; July 29, 2021. Accessed August 5, 2021.