— Cognitive tests show “notable reduction” in memory ability
by Judy George
Seven in 10 people, most of whom said they had long COVID, experienced concentration and memory problems months after acute SARS-CoV-2 infection and many performed worse than their peers on cognitive tests, initial data from the COVID and Cognition Study showed.
Among 181 participants, 78% said they had difficulty concentrating, 69% reported brain fog, 68% reported forgetfulness, and 60% said they had problems finding the right word when speaking, reported Lucy Cheke, PhD, of the University of Cambridge in England, and co-authors
These symptoms were reflected in a significantly lower ability to remember words and pictures in cognitive tests, the researchers reported in Frontiers in Aging Neuroscience.
“This is one of the first studies to actively look at cognition in long COVID,” Cheke told MedPage Today. “We found a notable reduction in memory ability in those with ongoing symptoms.”
“We explored not only performance on a range of tasks, but how they related to symptoms during the acute and ongoing illness,” she continued. “We found that a cluster of symptoms characterized by fatigue, chest pain, body pains, headache and limb weakness experienced during the acute illness — that is, the first 3 weeks of infection — were predictive of cognitive symptoms and memory-test performance up to 6 months later.”
“We also found that experience of ongoing neurological symptoms, such as disorientation, confusion, speech difficulty, and visual disturbances, were predictive of both executive function and memory deficits,” Cheke added. “These findings help us to narrow down the potential processes producing cognitive deficits.
The COVID and Cognition Study included both cross-sectional and longitudinal data to help understand cognitive problems in long COVID. Participants answered questions about demographics, medical history and health-related behaviors (such as smoking and exercise), and details about their symptoms and experience with COVID-19.
Participants were recruited from October 2020 to March 2021. As part of the study, they took language and memory tests (incorporating word list, associative memory, and category fluency variables) and completed executive function tasks (including mental rotation and sorting test variables). Their results were compared with similar people who never were infected with SARS-CoV-2.
The analysis included 181 people (72% women) who had SARS-CoV-2 infection and 185 (64% women) who had not been infected. Most had COVID-19 at least 6 months before the study began, and very few were hospitalized.
Most participants (68%) who were infected with COVID were 18 to 50 years old. About three-quarters lived in the United Kingdom; others lived in North America and other parts of the world. Most people in the study were white.
People who had been infected with SARS-CoV-2 had reduced performance on memory variables after adjusting for demographics, regardless of ongoing COVID symptoms. A closer look revealed that people who had been infected had an increased reaction time when performing a verbal memory task.
Overall, people with more severe ongoing COVID symptoms had worse scores on memory tasks than people who had recovered. Both performance (percentage of correct answers) and reaction time of verbal memory were significantly affected by severity of ongoing illness in a dose-dependent manner.
The picture was less clear for non-verbal associative memory, but pairwise analyses showed that people who were never infected with SARS-CoV-2 performed better than people who had severe ongoing symptoms.
A separate analysis showed that clusters of ongoing neurologic, cardiopulmonary, fatigue, gastrointestinal, autoimmune, mood, and appetite loss symptoms predicted current cognitive difficulties. People who were still experiencing neurologic symptoms were particularly impaired on cognitive tests.
About half of people with long COVID said it was hard to get medical professionals to take their symptoms seriously. Of those with severe ongoing symptoms, 75% said they had long periods of being unable to work.
“Memory difficulties can significantly affect people’s daily lives, including the ability to do their jobs properly,” co-author Muzaffer Kaser, MD, PhD, also of the University of Cambridge, told MedPage Today.
“Our findings suggest that more comprehensive assessments are needed to understand the breadth of problems with memory and other cognitive abilities,” he said. “We will continue to follow-up our participants, which will help us identify which difficulties persist over time and which cognitive problems may be candidates for future treatments.”
The study had several limitations, including reliance on self-reported symptoms. Cognitive testing, some of which occurred during pandemic lockdown periods, was conducted online.
The researchers continue to follow participants and plan to show changes in symptoms and cognitive performance over time. The group is also recruiting adults and children for additional evaluations about cognition and COVID-19.