preliminary results of new research suggest.
The findings provide important insight into the long-term cognitive impact of COVID-19, said study investigator Gabriela Gonzalez-Alemán, PhD, professor at Pontifical Catholic University of Argentina, Buenos Aires.
The more information that can be gathered on factors increasing risks for this cognitive impact, “the better we can track it and begin to develop methods to prevent it,” she said.
The findings were presented at the Alzheimer’s Association International Conference.
Memory, attention problems
COVID-19 has infected more than 570 million people worldwide. Related infections may result in long-term sequelae, including neuropsychiatric symptoms, said Dr. Gonzalez-Alemán.
In older adults, COVID-19 sequelae may resemble early Alzheimer’s disease, and the two conditions may share risk factors and blood biomarkers.
The new study highlighted 1-year results from a large, prospective cohort study from Argentina. Researchers used measures to evaluate long-term consequences of COVID-19 in older adults recommended by the Alzheimer’s Association Consortium on Chronic Neuropsychiatric Sequelae of SARS-CoV-2 infection (CNS SC2).
Harmonizing definitions and methodologies for studying COVID-19’s impact on the brain allows consortium members to compare study results, said Dr. Gonzalez-Alemán.
The investigators used the health registry in the province of Jujuy, situated in the extreme northwestern part of Argentina. The registry includes all SARS-CoV-2 testing data for the entire region.
The investigators randomly invited adults aged 60 years and older from the registry to participate in the study. The current analysis included 766 adults aged 55-95 years (mean age 66.9 years; 57% female) with an average of 10.4 years of education. The education system in Argentina includes 12 years of school before university.
Investigators stratified subjects by polymerase chain reaction testing status. Of the total, 88.4% were infected with COVID and 11.6% were controls (subjects without COVID).
The neurocognitive assessment of participants included four cognitive domains: memory, attention, language, and executive function, and an olfactory test that determined degree of olfactory dysfunction. Cognitive impairment was defined as z scores below –2.
Researchers divided participants into groups according to cognitive performance. These included normal cognition, memory-only impairment (single domain; 11.7%), impairment in attention and executive function without memory impairment (two domains; 8.3%), and multiple domain impairment (11.6%).
“Our participants showed a predominance of memory impairment as would be seen in Alzheimer’s disease,” noted Dr. Gonzalez-Alemán. “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 the subjects that had a severe cognitive impairment also had anosmia [loss of smell],” said Dr. Gonzalez-Alemán. “We established an association between olfactory dysfunction and cognitive performance and impairment.”
The analysis showed that severity of anosmia, but not clinical status, significantly predicted cognitive impairment. “So, anosmia could be a good predictor of cognitive impairment after COVID-19 infection,” said Dr. Gonzalez-Alemán.
For individuals older than 60 years, cognitive impairment can be persistent, as can be olfactory dysfunction, she added.
Results of a 1-year phone survey showed about 71.8% of subjects had received three vaccine doses and 24.9% two doses. About 12.5% of those with three doses were reinfected and 23.3% of those with two doses were reinfected.