Neurology Advisor Over 4.4 years of follow-up, the cumulative incidence of MCI was 27% (95% CI, 17%–40%) among patients with long COVID, 5% (95% CI, 2%–10%) among recovered COVID-positive patients, and 1% (95% CI, 0.2%–4%) among COVID-negative control individuals. Long COVID was associated with a higher hazard of MCI compared with individuals without long COVID (hazard ratio [HR], 3.93; 95% CI, 1.86–8.31; P <.001). The hazard of Alzheimer disease (AD)–related MCI was also higher among patients with long COVID (HR, 3.20; 95% CI, 1.14–9.0; P =.027).
Overall, 14% of participants (n=37) were diagnosed with MCI, and 0.4% of participants with long COVID (n=1) were diagnosed with AD dementia. Among those with long COVID, the most common MCI subtype was AD–related MCI.