Neurocognitive deficits in severe COVID-19 infection: Case series and proposed model.

To date, very few studies investigating neurocognitive deficits in COVID-19 have been published. This case series addresses cognition in post-COVID-19 patient by describing three patients in acute rehabilitation to inform a model of cognitive sequelae of COVID-19. Three English-speaking inpatients with severe symptoms and long-term intensive care unit (ICU) treatment are described. All patients had a premorbid history of hypertension and hyperlipidemia and experienced delirium and hypoxemia when hospitalized. Patient 1 is a 62-year-old male with 15 years of education with additional history of obstructive sleep apnea and type 2 diabetes. Patient 2 is a 73-year-old female with 12 years of education with a premorbid medical history of alcohol use disorder and Guillain-Barre syndrome. Patient 3 is a 75-year-old male with 14 years of education. No patients had premorbid psychiatric histories. The three patients demonstrated deficits on formal neuropsychological testing, particularly with encoding and verbal fluency. Memory measures improved with a more structured story memory task compared to a less-structured verbal list-learning task, suggesting executive dysfunction impacted learning. None of the patients demonstrated rapid forgetting of information. Two patients endorsed new depressive and/or anxiety symptoms. The results suggest evidence for neurocognitive deficits after severe COVID-19 infection, particularly in encoding and verbal fluency. These results were interpreted with caution given the limited number of patients and the telephone-based battery. The specific mechanism that caused these cognitive deficits in these individuals remains unclear. A proposed three-stage model of cognitive dysfunction is described to help guide future research.