COVCOG 2: Cognitive and Memory Deficits in Long COVID: A Second Publication from the COVID and Cognition Study

Abstract

Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been often characterized as a respiratory disease. However, it is increasingly being understood as an infection that impacts multiple systems, and many patients report neurological symptoms. Indeed, there is accumulating evidence for neural damage in some individuals, with recent studies suggesting loss of gray matter in multiple regions particularly in the left hemisphere. There are a number of mechanisms by which COVID-19 infection may lead to neurological symptoms and structural and functional changes in the brain, and cognitive problems are one of the most commonly reported symptoms in those suffering from Long COVID—the chronic illness following COVID-19 infection that affects between 10–25% of sufferers. However, there is as yet little research testing cognition in Long COVID. The COVID and Cognition Study is a cross-sectional/longitudinal study aiming to understand cognitive problems in Long COVID. The first paper from the study explored the characteristics of our sample of 181 individuals who had suffered COVID-19 infection, and 185 who had not, and the factors that predicted ongoing symptoms and self-reported cognitive deficits. In this second paper from the study, we assess this sample on tests of memory, language and executive function. We hypothesize that performance on “objective” cognitive tests will reflect self-reported cognitive symptoms. We further hypothesize that some symptom profiles may be more predictive of cognitive performance than others, perhaps giving some information as to mechanism. We found a consistent pattern of memory deficits in those that had suffered COVID-19 infection, with deficit increasing with severity of self-reported ongoing symptoms. Fatigue/Systemic symptoms during the initial illness and ongoing neurological symptoms were predictive of cognitive performance.

Long term neuropsychiatric consequences in COVID-19 survivors: Cognitive impairment and inflammatory underpinnings fifteen months after discharge

“…Cognitive deficit is one of the most common symptoms reported in research into Long COVID. Those who experienced “post-COVID-19 syndrome”/ “post-acute sequalae SARS-CoV-2”/ “Long COVID” following the COVID-19 infection may have cognitive dysfunction ( Guo et al, 2022 ). Based on our understanding of the mechanism of the virus in the CNS and the emerging evidences available, one can expect to have a variety of cognitive consequences of COVID-19 infection including attention, dysexecutive symptoms and hypoperfusion ( Kumar et al, 2021 ).…”

COVID-19 vaccination may enhance hippocampal neurogenesis in adults

“…The continued hippocampal neurogenesis in adults is crucial for adapting to the new life circumstances and protecting against age-related cognitive decline ( Kumar et al, 2019 ). Emerging evidence suggests a detrimental impact of COVID-19 illness on adult hippocampal neurogenesis (AHN) not only during the acute illness phase ( Fernández-Castañeda et al, 2022 , Klein et al, 2021 ) but also as a long-term impact ( Guo et al, 2022 ). On the contrary, the available literature on respiratory system diseases, such as influenza and tuberculosis, suggests that vaccine-induced adaptive immunity creates a neurotrophic milieu that can not only block the detrimental influence of acute infection on the AHN but also may enhance it ( Qi, 2015 ).…”

“Brain fog” and COVID-19

“…The term “brain fog” has been frequently attributed to COVID-19 infections and widely publicized in mass media as a long term neurological consequence of COVID-19, in addition to other symptoms of long COVID syndrome such as fatigue and cognitive problems. 1 , 2 , 3 Frequently, patients describe their “brain fog” symptoms as “slow and sluggish thinking”, “fuzziness” and “blur” feelings, and “not their usual self”. While “brain fog” is not a scientific diagnosis, the collections of patients’ perceived symptoms (which may also include memory, inattention and language deficits) have attracted considerable attention in the scientific community even though there is no quantifiable definition of “brain fog”.…”

“…We searched the key words “brain fog”, “COVID-19”, in PubMed and Embase from 1st May 2020 to 30 th June 2022 and identified 3 clinical studies (with sample size of >50 subjects and with age >18 years old) 1 , 2 , 3 and 2 biological studies 4 , 5 that examined the association of post COVID-19 infections and “brain fog”.…”