As a predictor of cognitive decline, COVID is superior to severity of olfactory loss

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Olfactory loss, but not disease severity, predicts persistent cognitive impairment 1 year after SARS-CoV-2 infection, preliminary findings of new research.

Researcher Gabriela Gonzalez-Aleman, PhD, a professor at the Pontifical Catholic University of Argentina in Buenos Aires, said the findings provide important insight into the long-term cognitive impact of COVID-19. Medscape Medical News.

The more information is gathered about the increased risk factors for this cognitive effect, “the better we can start to track it and develop ways to prevent it,” he said.

The findings were presented at the Alzheimer’s Association International Conference (AAIC) in 2022.

Memory, attention problems

COVID-19 has infected more than 570 million people worldwide. Associated infections can have long-term consequences, including neuropsychiatric symptoms, Gonzalez-Aleman said.

In older adults, the effects of COVID-19 may be similar to Alzheimer’s disease (AD), and the two conditions may share risk factors and blood biomarkers.



Dr. Gabriela Gonzalez-Aleman

A new study highlights the 1-year results of a large, prospective cohort study from Argentina. The researchers used measures recommended by the Alzheimer’s Association’s Consortium on Chronic Neuropsychiatric Consequences of SARS-CoV-2 Infection (CNS SC2) to assess the long-term effects of COVID-19 in the elderly.

Harmonizing definitions and methodologies for studying the impact of Covid-19 on the brain will allow consortium members to compare research results, González-Aleman said.

The investigators used a health registry in the province of Jujuy, in the northwesternmost part of Argentina. The registry contains SARS-CoV-2 testing data for the entire region.

The investigators randomly invited men aged 60 years and older from the registry to participate in the study. The current analysis included 766 adults aged 55–95 (mean age 66.9 years; 57% female) with a mean education of 10.4 years. Argentina’s education system includes 12 years of pre-university schooling.

The investigators stratified subjects using polymerase chain reaction (PCR) test condition. A total of 88.4% were infected with COVID and 11.6% were controls (subjects without COVID).

Neurocognitive assessment of participants included four cognitive domains: memory, attention, language and executive function, and an olfaction test that determined the degree of olfactory impairment. Cognitive impairment was defined as Z-scores below – 2.

The researchers divided the participants into groups based on their cognitive performance. These included normal cognition, memory impairment (one domain; 11.7%), attention and executive function impairment without memory impairment (two domains; 8.3%), and multiple domain impairment (11.6%).

“Our participants showed the memory impairment seen in Alzheimer’s disease,” González-Aleman noted. “And a large group showed a combination of memory and attention problems.”

About 40% of the study sample – but no controls – had olfactory dysfunction.

“All subjects with severe cognitive impairment also had anosmia [loss of smell]”, González-Aleman said. “We established a link between olfactory dysfunction and cognitive impairment and impairment.”

Analysis showed that severity of anosmia, but not clinical status, significantly predicted cognitive impairment. “Thus, anosmia may be a good predictor of cognitive decline after COVID-19 infection,” González-Aleman said..

For people over 60, cognitive impairment can be permanent, as can olfactory function, he added.

Results of the 1-year telephone survey showed that 71.8% of subjects received three doses of the vaccine and 24.9% received two doses. 12.5% ​​of those who received three doses and 23.3% of those who received two doses were reinfected.

Longest observation to date

Commenting on research for Medscape Medical NewsHeather Snyder, PhD, vice president of medical and scientific communications at the Alzheimer’s Association, noted that the study is “the longest follow-up we’ve seen” looking at the link between permanent loss of smell and cognitive changes after COVID-19. infection.

The study included a “significantly large” sample size and was “unique” because it was created in one part of the country with centralized testing, Snyder said.

The Argentinian group is one of the frontrunners to connect to CNS SC2, Snyder said.

Members of this Alzheimer’s Association consortium, Snyder said, are sharing updates on ongoing research at various stages and looking at the various neuropsychiatric effects of COVID-19. It’s important to bring these groups together to determine what those impacts are “because no one group can do it on its own,” he said.

“We noticed early on that some people had changes in their brains, or changes in cognition, loss of smell or taste, which suggests that there is a connection to the brain.”

But, he added, “there’s a lot more we don’t know” about the connection.

The study was funded by the Alzheimer’s Association and FULTRA.

Alzheimer’s Association International Conference (AAIC) 2022. Abstract 66868. Presentation July 31, 2022.

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