On a smartphone app, participants completed a battery of cognitive tests measuring several domains, including working memory, attention, reasoning, and motor control, with a composite score of accuracy and reaction times being the main outcome measure. Age, sex, education, ethnicity, socio-demographic factors and prior health conditions were included in the model. At Round 1, individuals who tested positive for SARS-CoV-2 had lower cognitive accuracy (β = −0.14 standard deviations (SD)) than negative controls. Individuals experiencing symptoms ≥ 12 weeks had large effect sizes (β = −0.22 SDs), which were comparable to hospital presentation during illness (β = −0.31 SDs), and 10 years age difference (β = −0.21 SDs). These deficits were only detectable in SARS-CoV-2 positive individuals who subjectively felt not recovered from COVID-19, whereas individuals who reported full recovery had no cognitive deficits. The longitudinal analysis between Round 1 and Round 2 showed no evidence of cognitive change over time, suggesting that cognitive deficits for affected individuals persisted at almost 2 years since initial infection.
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Observational study: prospective longitudinal cohort