Long-term cognitive functioning following COVID-19: Negligible neuropsychological changes over time

Abstract

Objective: Objective cognitive impairment has been shown in a minority of hospitalized COVID-19 patients, and longitudinal studies with a relatively long follow-up duration are scarce. We sought to investigate the presence and long-term change of objective cognitive functioning. Method: Forty-six initially hospitalized (18 ± 19 days) COVID-19 survivors (male/female: 30/16; age: 61 ± 11) underwent extensive neuropsychological assessment (including performance validity) approximately 1 (T1) and 2.5 years (T2) post-infection. Cognitive domains assessed were: memory, attention, executive functioning, processing speed, and language (n = 14 (sub)tests). We used normative data to derive age, sex, and education-adjusted T-scores (T ≤ 35 [≤-1.5SD], deficit cut-off). Repeated measures AN(C)OVAs were used to investigate cognitive functioning over time. Results: Mean neuropsychological performance (n = 14 tests) was within normal range at both timepoints, and number of individuals with objective cognitive deficits ranged from 0-20% (T1), and 2-22% (T2). Number of subjective cognitive complaints remained unchanged. A minority (17%) showed objective cognitive deficits on ≥2 tests at both 1 and 2.5 years post-infection, but not consistently within one cognitive domain. Longitudinal analyses on the total sample showed improvement in performance over time on phonemic fluency (p<.001), but stable cognitive performance on all other tests, independent of prior comorbidities, subjective cognitive complaints, depressive symptoms, and ICU admission. Conclusions: There were no consistent objective cognitive deficits or major cognitive disorders years after SARS-CoV-2 infection in the majority of cases. Neuropsychological functioning remained essentially unchanged over time. Future larger longitudinal studies are necessary to unravel COVID-19-related cognitive phenotypes of persisting deficits and how these can be modulated.