Prolonged COVID-19 symptoms associated with cognitive deficits

1. In this retrospective study, in patients with prolonged symptoms of coronavirus disease 2019 (COVID-19), cognitive deficits lasting a year or longer were more likely to be reported.

2. The greatest associations with cognitive deficits were found in individuals affected by COVID-19 near the beginning of the pandemic and those hospitalized.

Evidence Rating Level: 2 (Good)

Study Rundown: Coronavirus disease has been implicated in having negative long-term effects such as brain fog and poor memory. In the present study, participants were tasked with completing eight cognitive tests on their devices. The cognitive aspects included immediate memory, two-dimensional mental manipulation, spatial working memory, spatial planning, verbal analogical reasoning, word definitions, information sampling, and delayed memory. Participants were separated into six groups based on their COVID-19 infection history, with category 1 meaning no COVID-19 up to category 6 meaning the presence of symptoms at least 12 weeks after infection began and had not resolved by the initiation of the cognitive assessment. Approximately 800,000 individuals aged 18 or older were invited to participate in the study by completing an online cognitive function assessment. To limit the amount of confounding, propensity-score matching was used. The study’s results showed that COVID-19 infection was associated with longer-term cognitive defects. Furthermore, as the pandemic continued, the association between COVID-19 and cognitive losses decreased. The study could not assess causality as baseline cognitive data was not recorded, so cognitive change could not be measured. Overall, cognitive deficits had the strongest association with hospitalization, longer illness, and infection during the period of the original or alpha variant.

Click here to read the study in the NEJM

In-Depth [retrospective cohort]: This study included a total of 112,964 individuals who responded to an online survey. The multiple regression analysis found similar deficit results when comparing the resolved-symptoms groups with the no-COVID-19 group (e.g., in the group with resolved symptoms at <4 weeks, -0.23 SD [95% Confidence Interval [CI], -0.33 to -0.13]; and in the group with resolved symptoms at ≥12 weeks, -0.24 SD [95% CI, -0.36 to -0.12]). Participants who were infected with COVID-19 during either the original virus period or the alpha variant period had some of the greatest deficits in cognitive scores compared to those infected during a later variant (e.g., -0.17 SD for the alpha variant vs. the omicron variant; 95% [CI], -0.20 to -0.13). The greatest deficits were also seen when comparing the unresolved persistent symptom group to the no-COVID-19 group (-0.42 SD; 95% CI, -0.53 to -0.31) and among those hospitalized for COVID-19 compared with those not hospitalized (e.g., intensive care unit admission, -0.35 SD; 9% CI, -0.49 to -0.20). Similar deficit results were found when comparing the resolved-symptoms groups with the no-COVID-19 group (e.g., in the group with resolved symptoms at <4 weeks, -0.23 SD [95% CI, -0.33 to -0.13]; and in the group with resolved symptoms at ≥ 12 weeks, -0.24 SD [95% CI, -0.36 to -0.12]). When compared to the no-COVID-19 group, the COVID-19 group with unresolved symptoms experienced a deficit in memory, reasoning, and executive function tasks (-0.33 to -0.20 SD). Overall, COVID-19 infection may lead to cognitive deficits persisting for a year or longer.

Image: PD

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