Cognitive functioning in young adults after mild COVID-19: A case-control study from Iran

Since December 2019, the novel coronavirus (COVID-19) has caused widespread infection across global populations, characterized by its high transmissibility. Despite extensive research on the acute effects of COVID-19, the long-term psychological and neurological sequela remain inadequately explored. This study aimed to investigate cognitive function after COVID-19 infection compared to a control group of non-infected subjects.

This case-control study included 40 individuals who had recovered from COVID-19, referred to Imam Reza Referral and Educational Hospital in Mashhad, Iran, and 40 matched controls who had not experienced COVID-19 symptoms. All participants underwent an initial screening by a psychiatric assistant to exclude significant medical and psychiatric conditions and any history of drug use. A demographic checklist was administered, followed by cognitive assessments using the Stroop Test, Digit Span Test, and Wisconsin Card Sorting Test (WCST). Data were analysed using SPSS Version 20.

No significant differences were observed between the two groups regarding age, sex, education level, marital status, or employment status (p > 0.05). However, COVID-19-infected individuals exhibited significantly longer completion times for the congruent Stroop test and increased reaction times compared to healthy controls (p < 0.05). Additionally, the duration for completing the Wisconsin Card Sorting Test was significantly longer in the infected group compared to the non-infected group (p < 0.001). Although the longest digit span and scores on the Digit Span Test were lower in the infected group, these differences did not reach statistical significance (p > 0.05). Furthermore, reaction times in the Continuous Performance Test (CPT) for the first, second, and third sets of 50 stimuli were significantly greater in the COVID-19 group (p < 0.001).

This study underscores that cognitive performance post-COVID-19 is adversely affected, particularly in terms of processing speed and sustained attention, when compared to healthy individuals. Further research is warranted to elucidate the underlying mechanisms and to explore potential interventions for cognitive rehabilitation in this population.