Cognitive dysfunction associated with COVID-19: A comprehensive neuropsychological study

Abstract

Objective: Recent evidence suggests that patients suffering post-acute COVID syndrome frequently report cognitive complaints, but their characteristics and pathophysiology are unknown. This study aims to determine the characteristics of cognitive dysfunction in patients reporting cognitive complaints after COVID-19 and to evaluate the correlation between cognitive function and anxiety, depression, sleep, and olfactory function.

Methods: Cross-sectional study involving 50 patients with COVID-19 reporting cognitive complaints 9.12 ± 3.46 months after the acute infection. Patients were evaluated with a comprehensive neuropsychological protocol, and scales of fatigue, depression, anxiety, sleep and an olfactory test. Normative data and an age- and education matched healthy control group were used for comparison.

Results: COVID-19 patients showed a diminished performance on several tests evaluating attention and executive function, with alterations in processing speed, divided attention, selective attention, visual vigilance, intrinsic alertness, working memory, and inhibition; episodic memory; and visuospatial processing. Cognitive performance was correlated with olfactory dysfunction, and sleep quality and anxiety to a lesser extent, but not depression.

Conclusions: Patients with COVID-19 reporting cognitive symptoms showed a reduced cognitive performance, especially in the attention-concentration and executive functioning, episodic memory, and visuospatial processing domains. Future studies are necessary to disentangle the specific mechanisms associated with COVID-19 cognitive dysfunction.

Keywords: COVID-19; Cognitive; Long-term COVID; Neuropsychological assessment.

Fig. 1

Radar chart representing the percentage of patients showing age- and education-adjusted scaled score ≤5 in healthy controls (green) and COVID-19 (blue) in standard tests. Each concentric line represents a 10%. Percentage in healthy controls is an estimate according to normative data. Abbreviations: BNT: Boston Naming Test; DSF: Digit Span Forward; DSB: Digit span backwards; CF: Corsi forward; CB: Corsi Backwards; FCSRT: Free and Cued Selective Reminding Test (FR1: Free Recall Trial 1; FTR: Free Total Recall; TR: Total Recall; DFR: Delayed Free Recall; DTR: Delayed Total Recall); JLO: Judgment Line Orientation; LF: letter fluency; ROCF: Rey-Osterrieth Complex Figure (c: copy accuracy; t: copy time; 3: memory at 3 min; 30: memory at 30 min; rec: recognition); SDMT: Symbol Digit Modalities Test; SF: Semantic Fluency; Stroop A (word reading); Stroop B (color naming); Stroop C (interference); VOSP: Visual Object Space Perception Battery (DP: discrimination of position; NL: number location; OD: object decision; PS: progressive silhouettes).

Fig. 2

Radar chart representing the percentage of patients showing z-scores ≤1.5 (or ≥1.5 when appropriate) in healthy controls (green) and COVID-19 (blue) in the computerized battery. Each concentric line represents a 10%. Abbreviations: COG: Cognitrone (i: total correct rejection; t: mean time correct rejection); DT: determination test; NBV: N-back verbal; FGT (DFR1: Delayed Free Recognition at 5 min, DFR2: Delayed Free Recognition at 30 min; LT: Learning Total; R: Recognition); RT: Reaction Test; TMT: Trail Making Test; ToL: Tower of London.

Fig. 3

Heatmap of Pearson correlations between STAI, PSQI, MFIS, BSIT, and BDI with neuropsychological tests (A: Standard tests; B: Computerized battery).