Cognitive function among COVID-19 survivors in the subacute phase during the epidemic of Omicron variant in China

Following the relaxation of pandemic control measures in China, the impact of coronavirus disease 2019 (COVID-19) on cognitive function in the Chinese population has not been investigated. Therefore, this study aimed to assess cognitive function and identify its risk factors in the subacute phase (<3 months) of COVID-19 patients during the epidemic wave of the Omicron variant. In this nationwide smartphone-based online assessment from January 15 to 29, 2023, the Integrated Cognitive Assessment (ICA) and the Number Ordering Test (NOT) were used to assess cognitive function. Among the 9663 participants, 8905 (92.2%) were COVID-19 survivors. These patients performed poorly on most neuropsychological results (P<0.05); however, after controlling for socio-demographics, only the ICA accuracies were lower (P<0.05, partial η²≤0.001). After the initial recovery, 5832 (65.5%) COVID-19 survivors reported inflexible thinking, 5419 (60.9%) noted slowed information processing speed, and 4344 (48.8%) reported insomnia. Female sex, older age, low education level, living in Northwest China, and insomnia were significantly associated with poor performance on the key neuropsychological results (range, absolute β values 0.023‒0.430, P<0.05). In the subacute phase of COVID-19, subjective cognitive complaints were highly prevalent, whereas objective cognitive differences were subtle. Despite the mild overall impact, vulnerable subgroups-such as females, older adults, individuals with low education level, and patients with insomnia-showed greater susceptibility to these cognitive changes.