Episodic long-term memory in post-infectious SARS-CoV-2 patients

Abstract

Background: Episodic long-term memory (LTM) difficulties/deficits are frequent in COVID-19-recovered patients and negatively impact on prognosis and outcome. However, little is known about their semiology and prevalence, also being still debated whether they arise from primary amnesic features or are secondary to dysexecutive/inattentive processes and disease-related/premorbid status. Hence, this study aimed at (1) assessing LTM functioning in post-infectious SARS-CoV-2 patients by accounting for premorbid and disease-related confounders and (2) exploring its cognitive etiology.

Methods: Measures of global cognition (Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA)) and LTM (Babcock Memory Test (BMT)) of fifty-four COVID-19-recovered patients were retrospectively collected. Patients were subdivided into those being already at risk or not for cognitive decline (RCD + ; RCD -). Cognitive measures were converted into equivalent scores (ESs).

Results: LTM sub-clinical/clinical deficits (ESs = 0/1) were mildly-to-moderately prevalent in both RCD + (MoCA-Memory, 31.8%; BMT, 31.8%) and RCD - (MoCA-Memory, 28.6%; BMT, 39.3%) patients. MMSE and MoCA total scores, but not the MoCA-Attention subtest, were associated with the BMT. RCD + asymptomatic patients performed better on the BMT (p = .033) than those requiring O₂ therapy (but not ventilation).

Discussion: COVID-19-recovered individuals might show LTM deficits of both primary and secondary etiology and should be thus screened for them, especially those having suffered mid-to-moderate COVID-19 and those already being at risk for cognitive decline. Both I- and II-level measures of verbal LTM can be adopted, although the former might be more sensitive.

Keywords: Attention; COVID-19; Cognitive assessment; Memory; SARS-CoV-2.