Cognitive impairment 2 years after mild to severe SARS-CoV-2 infection in a population-based study with matched-comparison groups.

COVID-19 may have long lasting cognitive consequences. Studies with a follow-up longer than 1 year after infection are lacking. This study presents the prevalence of cognitive impairment 2 years after SARS-CoV-2 infection in survivors of the first year of the pandemic and comparison groups matched 1:1 for sex, age, and level of care. Users of the Local Health Unit of Matosinhos (comprising almost all citizens of the municipality) were retrospectively selected according to hospitalization and SARS-CoV-2 infection between March 2020 and February 2021: group #1, hospitalized for COVID-19 (n = 101); group #2, hospitalized, uninfected (n = 87); group #3, non-hospitalized, infected (n = 252); group #4, non-hospitalized, uninfected (n = 258). Between July 2022 and October 2023, all participants completed the Montreal Cognitive Assessment. Those with a score below 1.5 SD of age- and education-specific norms (n = 279) were invited for a comprehensive neuropsychological assessment to identify cognitive impairment. The prevalence of cognitive impairment was higher in group #1 than #2 (19.1% vs. 6.8%; adjusted OR 5.41, 95% CI 1.54, 19.03) and in group #3 than #4 (10.7% vs. 3.2%; adjusted OR 3.27, 95% CI 1.23, 8.67). These results suggest that specific care to timely diagnose and treat cognitive impairment is needed for COVID-19 survivors of the first year of the pandemic.