Post-acute sequelae of COVID-19 in young adults: Mental fatigue and decreased cognitive flexibility

Background and purpose - Post-acute sequelae of COVID-19 (PASC) describes the occurrence of persistent symptoms following COVID-19 infection. Neurological and psychiatric symptoms may include fatigue, post-exertional malaise, cognitive complaints, sensorimotor symptoms, headache, insomnia, depression, and post-traumatic stress disorder. The aim of this study was to evaluate the long-term effects of COVID-19 infection on mental fatigue and cognitive flexibility in young adults. Methods - Simple random sampling method was used to enroll university students into the study between December 25 and 31, 2022. The time since active infection, central neurological findings (such as headache, dizziness, and loss of smell or taste), and the presence of lung involvement were recorded. The Mental Fatigue Scale (MFS) and the Cognitive Flexibility Inventory (CFI) were administered to all participants. Results - The study included 102 cases and 111 controls. The case group had a significantly higher total MFS score (12.95; 9.69 respectively) (p<0.001) and significantly lower total CFI score (100.01; 109.84 respectively) (p<0.001) than the control group. The case group experienced more frequent mental fatigue than the control group (p<0.001). Among all participants, a history of COVID-19 infection was identified as a risk factor for developing mental fatigue (odds ratio/OR: 2.74). In the case group, female sex (OR: 0.38) and lung involvement (OR: 10.74) were risk factors for developing mental fatigue. Conclusion - This study demonstrates that COVID-19 infection might have long-term negative effects on cognitive health, likely due to a combination of organic and psychogenic mechanisms.