Memory and metamemory performance in individuals with and without post-COVID-19 subjective cognitive symptoms

Metamemory is the awareness of and ability to evaluate one's own cognitive abilities. This study examined impaired metamemory as a possible mechanism contributing to persistent cognitive symptoms after COVID-19.

Individuals with previous COVID-19 illness were recruited. Participants completed questionnaires regarding physical health, mental health, and their COVID-19 illness. To assess memory and metamemory performance, participants were presented with 50 words and then completed a two-alternative forced choice recognition memory task with a confidence rating after each trial. This was repeated for 3 blocks of 50 trials each. A signal detection theory framework was applied to derive metrics of memory performance (d'), metamemory performance (meta-d'), and metamemory efficiency (M-ratio). We compared participants who self-reported persistent cognitive symptoms at the time of their metamemory assessment (n = 47) to participants who denied persistent cognitive symptoms (n = 87). We used a general linear model to compare groups, covarying for age and days between COVID-19 and metamemory assessment.

Participants with and without self-reported persistent cognitive symptoms did not differ on memory performance (d': p = .24, $\beta$ = 0.22 95% CI [-0.1, 0.6]), metamemory performance (meta-d': p = .28, $\beta$ = 0.20 95% CI [-0.2, 0.6]), or metamemory efficiency (M-ratio: p = .85, $\beta$ = -0.04 95% CI [-0.4, 0.3]). Those with persistent cognitive symptoms reported a higher degree of depression (p < 0.001, $\beta$ = 0.83 95% CI [0.5, 1.2]), anxiety (p = 0.016, $\beta$ = 0.50 95% CI [0.2, 0.9]), and somatic symptom scores (p < 0.001, $\beta$ = 0.92 95% CI [0.5, 1.3]).

Patients with and without self-reported persistent cognitive symptoms had similar memory accuracy and both demonstrated good (synchronous) awareness of their memory test performance. While both cognitive and metacognitive impairment appear unlikely to drive cognitive symptoms after COVID-19, psychological distress (particularly anxiety) remains a compelling candidate perpetuating factor. Future mechanistic research is necessary to understand if and how psychological distress contributes to cognitive symptoms, and vice versa.