Self-reported immune status and COVID-19 associated subjective cognitive functioning in post-COVID-19 syndrome: Examination of an Irish cohort.

Introduction: Cognitive changes are very frequently reported by people with post-COVID-19 syndrome (PCS), but there is limited understanding of the underpinning mechanisms leading to these difficulties. It is possible that cognitive difficulties are related to immune status and/or low mood. The aim of the present study was to examine the relationship between immune status and cognitive functioning in PCS, while considering whether depression symptoms also influence this association.

Methods: Participants were recruited in an online study of cognitive and psychological consequences of PCS, involving individuals attending a post-COVID clinic in an acute general hospital in Ireland, and a comparison sample of age- and sex-matched community controls who had also been infected with COVID-19 but had not experienced PCS. Participants with PCS (n = 71) and community controls (n = 50) completed the immune status questionnaire, Cognitive Failures Questionnaire (CFQ), Hospital Anxiety and Depression Scale (HADS), and the Functional Assessment of Chronic Illness Therapy-Fatigue Scale (FACIT-F).

Results: Significant differences were observed between groups in terms of perceived immune status, perceived cognitive function, depression scores, and fatigue, with the "PCS" group reporting lower immune status, more cognitive difficulties, and higher levels of depression and fatigue. Regression analysis in the PCS group indicated that immune status and depression significantly contributed to variance in subjective cognitive functioning, with immune status remaining a significant predictor of cognitive functioning scores even when accounting for depression, fatigue, and other covariates related to PCS, such as Body Mass Index (BMI).

Conclusion: Our findings suggest that subjective cognitive functioning is influenced by self-reported immune status in PCS, emphasising the importance of immune status, cognitive, and mood screening as part of routine clinical care in PCS.