Cognition and Memory Following COVID-19 in a Large Community Sample

Background Cognitive symptoms post-COVID are well-recognized, but it is unclear whether objectively measurable cognitive deficits exist and, if so, how long they persist. Methods Of 800,000 adults from the REal-time Assessment of Community Transmission (REACT) study in England, 141,583 started (112,964 completed) an online assessment of cognitive function (“Cognitron”). We estimated a global cognitive factor (G) across eight tasks. We hypothesized that people with persistent symptoms (>12 weeks) post-COVID had objectively measurable global cognitive deficits, and secondarily, that there were executive and memory impairments in such participants, especially those reporting recent poor memory or “brain fog.” Results In multiple regression (similarly on propensity score matching), recovered mild COVID-19 cases showed small deficits in global cognition relative to uninfected-unconfirmed participants (-0.23SD 95% Confidence Interval (CI), -0.33 to -0.13). Deficits were larger for participants with unresolved persistent symptoms post-COVID (-0.42SD 95% CI, -0.53 to -0.31), infection during Wildtype- or Alpha-variant periods vs. later variant periods (-0.17SD 95% CI, -0.13 to -0.20), and among hospitalized vs. non-hospitalized cases (-0.35SD 95% CI, -0.49 to -0.20). Memory, reasoning and executive tasks were the most sensitive (unresolved persistent symptom group, -0.20SD to -0.33SD) and correlated weakly with recent symptoms including poor memory and “brain fog.” No adverse events were reported during this observational study. Conclusions Participants with resolved persistent symptoms post-COVID appeared to recover objectively measured cognitive functions to a similar degree as shorter-duration cases, although mild COVID-19 was still associated with small cognitive deficits post-recovery. Longer-term persistence of cognitive deficits and any clinical implications remain uncertain.