Cognitive Deficits Observed in Aftermath of Both Short- and Long-COVID-19
Cognitive deficits following COVID-19 infection, whether resolved after a short duration or longer-term persistence, have been confirmed through objective measurement. Results from the observational study were published in The New England Journal of Medicine.
“Multiple findings indicated that the association between Covid-19 and cognitive deficits attenuated as the pandemic progressed,” said Professor Adam Hampshire, PhD, Department of Brain Sciences at Imperial College London, and co-authors. “We found smaller cognitive deficits among participants who had been infected during recent variant periods than among those who had been infected with the original virus or the alpha variant.”
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The authors recruited their study cohort from an English national SARS-CoV-2 monitoring program (REACT-1) that ran from May 1, 2020, to March 31, 2022, and included over 3 million randomly-selected adults. For the present study, a subsample of 800,000 adults were invited to complete a follow-up survey and cognitive assessment, both administered virtually. The invited subsample included those who had tested positive for COVID-19 with symptoms persisting for at least 12 weeks, those from the REACT study who either tested positive from a PCR test or were unvaccinated and had tested positive for antibodies, and randomly selected participants from the remaining study population. Study participants were then categorized into 6 groups according to duration of their COVID-19 infection.
Overall, 112,964 adults of the invited sample completed the online cognitive assessment. Researchers made several notable insights based on small, but significant, associations, including:
- Participants who recovered from COVID-19 with symptoms resolution in less than 4 weeks or within at least 12 weeks, had similar small deficits in cognition as compared to participants who were not infected (-0.23 SD [95% confidence interval {CI}, -0.33 to -0.13]; and -0.24 SD [95% CI, -0.36 to -0.12], respectively).
- Larger cognitive deficits were observed in participants with “unresolved persistent symptoms” (-0.42 SD; 95% CI, -0.53 to -0.31) as well as in those who have been hospitalized (e.g., intensive care unit admission, −0.35 SD; 95% CI, −0.49 to −0.20).
- Larger cognitive deficits were also overserved in those infected earlier in the pandemic with the original strain or the B.1.1.7 variant (e.g., −0.17 SD for the B.1.1.7 variant vs. the B.1.1.529 variant; 95% CI, −0.20 to −0.13), with other findings indicating that “the association between Covid-19 and cognitive deficits attenuated as the pandemic progressed.” Infection during “peak strain on health services and a lack of proven effective treatments” were noted as additional contributing factors.
- Memory, reasoning, and executive function appeared to be the cognitive processes most sensitive to alteration by COVID-19 infection. Researchers observed a “small cognitive advantage” among participants who had received 2 or more vaccinations.
- Cognitive deficits appeared to be associated with mood swings, fatigue, and a variety of other symptoms.
“Although previous, often underpowered, studies have offered contradictory evidence for associations between mental health and cognitive deficits after COVID-19, our study was powered to detect small associations with high confidence,” noted Hampshire et al. “It is likely that multiple underlying factors contribute to cognitive deficits after COVID-19.”
The findings from this study may be limited by reliance on subjective reporting and participant self-selection bias. The study was supported by the National Institute for Health and Care Research, UK Research and Innovation, the Department of Health and Social Care in England, and the Huo Family Foundation.
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