Impact of COVID-19 on Cognition 

Early in the COVID-19 pandemic, reports began emerging of individuals who had recovered from infection but struggled with ongoing difficulties with memory, concentration, and more [1,2]. Colloquially dubbed “brain fog,” these lingering cognitive symptoms were linked to the broad syndrome called post-acute sequelae of SARS-CoV-2 infection (PASC), also known as “long Covid,” which can also manifest as fatigue, shortness of breath, cough, and/or loss of smell or taste [1,3,4,5]. Additional research has further elucidated how COVID-19 impacts cognition specifically, an area of particular importance due to its potential effects on an individual’s ability to return to their normal life and work. 

Cognitive impairment is known to be associated with severe illness in general – hospitalization and intensive care disrupt patients’ normal functioning, involve significant discomfort, and often require periods of immobility and sedation [1,3,4]. Current data show that those with severe COVID-19 are more likely to experience impairments to cognition even after clearing the infection [3,4,5]. In addition, severe infection is associated with a longer-lasting increase in biomarkers of cerebral injury, with some researchers hypothesizing that COVID-19 induces brain inflammation, in addition to inflammation in other organ systems, that then leads to the wide range of neuropsychiatric symptoms seen in patients [3]. 

A recent study sought to better characterize the cognitive deficits experienced by COVID-19 survivors, as well as identify correlates of symptom severity. Researchers administered a battery of tests to 46 participants who had been hospitalized with COVID-19 and to 460 matched controls. COVID-19 patients were less accurate and slower to respond. Results suggested that the cognitive profile of COVID-19 patients was distinct from that of normal ageing and dementia. Furthermore, researchers analyzed whether prior chronic mental health disorders were associated with greater impacts on cognition but found that they were not, though other studies have reported conflicting results [4]. 

However, research also shows that mild to moderate COVID-19 can also impair cognition [1-5]. An early study reported mild impairments in a small cohort of relatively young patients, especially in the areas of short-term memory, attention, and concentration, suggesting that those who are otherwise more healthy, including young people, cannot necessarily avoid serious, long-term difficulties [2]. 

Another study utilized a brain imaging approach to determine whether COVID-19 was associated with structural changes in the brain. Douaud et al. followed participants in an existing study and were thus able to compare scans from before and after infection. Data indicated decreased grey matter in two regions, increased markers of damage in areas related to the sense of smell, and a decrease in overall brain size in those who were infected, as well as a greater decline in cognition. These effects were seen in both severe and mild-to-moderate groups. However, continued follow-up is needed to verify the significance of these results in the long term [6]. 

Fortunately, increased awareness of these issues has led to the development of support structures for those affected by long-term cognitive impairments after COVID-19. Clinics to provide care and facilitate research have been established in many places [1], and the federal government has issued guidance on how the Americans with Disabilities Act may apply [5]. 

References 

[1] Kelly Servick. “COVID-19 ‘brain fog’ inspires search for causes and treatments,” Science, April 2021. https://www.science.org/content/article/covid-19-brain-fog-inspires-search-causes-and-treatments 

[2] M. S. Woo, J. Malsy, J. Pöttgen, et al. Frequent neurocognitive deficits after recovery from mild COVID-19. Brain Communications, Volume 2, Issue 2, 2020. DOI:10.1093/braincomms/fcaa205 

[3] A. Nalbandian, K. Sehgal, A. Gupta, et al. Post-acute COVID-19 syndrome. Nature Medicine, Volume 27, 2021. DOI:10.1038/s41591-021-01283-z 

[4] A. Hampshire, D. A. Chatfield, A. Manktelow, et al. Multivariate profile and acute-phase correlates of cognitive deficits in a COVID-19 hospitalised cohort. eClinicalMedicine, Volume 47, 2022. DOI:10.1016/j.eclinm.2022.101417 

[5] Office for Civil Rights. “Guidance on ‘Long COVID’ as a Disability Under the ADA, Section 504, and Section 1557,” U.S. Department of Health and Human Services, July 2021. https://www.hhs.gov/civil-rights/for-providers/civil-rights-covid19/guidance-long-covid-disability/index.html 

[6] G Douaud, S Lee, F Alfaro-Almagro, et al. SARS-CoV-2 is associated with changes in brain structure in UK Biobank. Nature, Volume 604, 2022. DOI: 10.1038/s41586-022-04569-5