1 Cognitive NeuroLab, Faculty of Health Sciences, Universitat Oberta de Catalunya, Barcelona, Spain. mcalabria@uoc.edu.
2 Neuropsychology Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
3 Department of Psychology, Concordia University, Montreal, Canada.
4 Centre for Research On Brain, Language & Music, Montreal, Canada.
5 Facultat de Psicologia, Ciències de l'Educació i l'Esport, Blanquerna, Universitat Ramon Llull, Barcelona, Spain.
6 Internal Medicine Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
7 Neuroradiology, Department of Radiology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
8 Universitat Autonoma Barcelona (UAB), Barcelona, Spain.
9 Headache Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.

Fatigue in its many forms of physical, mental, and psychosocial exhaustion is a common symptom of post-COVID-19 condition, also known as "Long COVID." Persistent fatigue in COVID-19 patients is frequently accompanied by cognitive dysfunction and neuropsychiatric symptoms; however, less is known about the relationships between these components of post-COVID-19 condition and fatigue itself. Consequently, the present study sought to (1) distinguish the types of fatigue experienced by participants, and (2) investigate whether cognitive deficits across various domains and neuropsychiatric conditions predicted these different types of fatigue. The study included 136 COVID-19 patients referred for neuropsychological evaluation due to cognitive complaints 8 months on average after SARS-CoV-2 infection. Measures included self-reported fatigue (physical, cognitive, and psychosocial), neuropsychiatric questionnaires (assessing symptoms of depression, anxiety, apathy, and executive functioning), a comprehensive neuropsychological assessment, and self-reported quality of life and everyday functioning. Results showed that reports of clinical significant fatigue were pervasive in our sample (82.3% of participants), with physical fatigue rated highest on average relative to the subscale maximum. Elevated levels of apathy, anxiety, and executive dysfunction in neuropsychiatric measures along with executive and attentional difficulties on cognitive tests were found to be consistently important predictors among different types of fatigue. This implicates both cognitive and neuropsychiatric symptoms as predictors of fatigue in post-COVID-19 condition, and stresses the importance of a holistic approach in assessing and considering potential treatment for COVID-19 patients experiencing fatigue.