Cognitive deficits were often reported during the acute and post-acute stages of severe COVID-19 and were often, but not always, associated with signs of brain damage. Population-wide surveys highlighted the need for investigations into the nature, the severity and the evolution of cognitive, behavioural and psychiatric deficits. In this observational study, we describe the outcome at 12 months after severe COVID-19 involving intensive care unit stay and critical chronic illness in six patients, who had no history of prior brain dysfunction. A pervading mental and physical fatigue was consistently reported as well as numerous multidomain complaints, which affect to a certain extent everyday life, and for some of the patients a certain degree of neurobehavioural (apathy) and/or psychiatric (anxiety) dysfunction. Standardized neuropsychological tests revealed for 4 of the 6 patients the occurrence relatively isolated of cognitive dysfunction or performance at the lower limit of the norm in some, but not all attentional, executive and/or working memory tests. Somatic scales highlighted the presence of dyspnoea, muscle weakness, an olfactory disorder and/or minor sleep problems in some but not all patients.