Sergey Malykh, Valeriia Demareva, Victoria Ismatullina, Timofey Adamovich, Tamara Malykh, Tatiana Tikhomirova
Our results support the hypothesis that long COVID is associated with objective working memory impairment, particularly among individuals with a clinical diagnosis. These findings add to the growing body of evidence linking long COVID to objective cognitive difficulties. Moreover, the study advocates the use of rapid, single-task online cognitive assessments as a practical, scalable, and low-burden approach for evaluating working memory function in this population.
Post-COVID symptoms frequently include cognitive complaints, yet evidence on objectively measured cognitive performance in large samples of young adults remains limited. This study examined associations between self-reported post-COVID consequences and objective cognitive performance in university students, with particular attention to acute COVID-19 severity. The sample comprised 7482 students aged 17-23 years: 3945 reported no previous COVID-19, 1676 reported previous COVID-19 without post-COVID consequences, and 1861 reported previous COVID-19 with post-COVID consequences. Visuospatial working memory was assessed using the Corsi Block Tapping Test (CTB), and choice-response performance was assessed using accuracy and mean correct-response latency in a four-choice reaction time task. Analyses accounted for age, sex, and clustering by university; among previously infected participants, models additionally adjusted for perceived acute COVID-19 severity. The primary adjusted analyses included 7117 participants for CTB and 6361 participants for the cleaned choice-response accuracy and latency analyses. In the three-group analysis, students reporting post-COVID consequences had slightly lower CTB scores than those without previous COVID-19 (B = -0.146, 95% CI [-0.277, -0.015], p = 0.029), although the effect was small and was not fully robust in an ordinal sensitivity model (OR = 0.91, 95% CI [0.82, 1.00], p = 0.052). No reduction in choice-response accuracy or robust slowing of response latency was observed in the post-COVID consequence group. Among previously infected participants, post-COVID consequences were not significantly associated with CTB performance (B = -0.149, 95% CI [-0.311, 0.013], p = 0.071), choice-response accuracy (OR = 0.80, 95% CI [0.60, 1.07], p = 0.126), or response latency (-0.79%, 95% CI [-2.06%, 0.49%], p = 0.224) after adjustment for acute severity, age, and sex; none of these associations remained significant after false discovery rate correction. Acute COVID-19 severity was likewise not significantly associated with the cognitive outcomes. Overall, self-reported post-COVID consequences were associated with, at most, small and outcome-dependent differences in objective cognitive performance in this young university sample. The findings do not support a broad objective cognitive deficit associated with self-reported post-COVID consequences after accounting for acute disease severity and demographic factors.