Cognitive impairment in long-COVID: frequency, trajectories and risk factors in a cohort study from Italy

Background: Data on cognitive impairment in patients with Long-COVID remain controversial. Methods: The study analyzed in patients followed for Long-COVID the frequency and risk factors for cognitive impairment (defined by a Montreal Cognitive Assessment [MoCA] score < 24 points), its associations with subjectively reported cognitive and psychological symptoms, and the evolution of cognitive impairment and cognitive symptoms over time. Results: At a mean interval of 259 days from COVID-19, the mean MoCA score recorded among 118 individuals was 25.5, with 32.2% of them showing scores < 24 points. Eighty-five patients (72.0%) presented persisting symptoms, predominantly represented by fatigue (35.6%), dyspnea (28.8%) and cognitive symptoms (24.6%). A MoCA score < 24 was significantly associated with older age, hospitalization during acute disease and female sex. Individuals with persisting cognitive symptoms had significantly lower MoCA scores compared to individuals without such symptoms, with a mean difference of 1.4 points. Anxiety and depression were not associated with lower MoCA scores. In a subsequent evaluation conducted in 66 individuals (55.9%) at an average interval of 959 days from COVID-19, the mean MoCA score decreased by 1.3 points (95%CI 0.5-2, p = 0.001), the frequency of a MoCA score < 24 increased from 25.8% to 36.4% (p = 0.090), and the prevalence of cognitive symptoms increased from 27.3% to 53.0% (p = 0.002). Discussion: Cognitive impairment in Long-COVID appeared common and persisting. Cognitive symptoms, unlike psychological symptoms, were associated with lower cognitive scores and tended to accumulate during follow-up. Advanced age, severity of acute SARS-CoV-2 disease and female sex should be considered as potential risk factors.