Self-reported Memory Problems Eight Months after Non-Hospitalized COVID-19 in a Large Cohort

Background Neurological manifestations of COVID-19 range from ageusia and anosmia, experienced by most patients, to altered consciousness and rare and severe encephalopathy. A direct affection of the central nervous system (CNS) in the disease has been supported by animal models and MRI findings in patients with mild and severe symptoms. Here we report eight-month data on memory problems for non-hospitalized COVID-19 patients compared to SARS-CoV-2 negative patients and untested volunteers. Objective To explore the association between non-hospitalized COVID-19 eight months previously and self-reported memory problems. Methods We followed a cohort of 13156 participants that was invited after (1) being tested for SARS-CoV-2 with a combined oropharyngeal- and nasopharyngeal swab or (2) randomly selected from the Norwegian population (untested). Participants completed online baseline- and follow-up questionnaires detailing underlying medical conditions, demographics, symptoms, and items from the RAND-36 questionnaire on health-related quality of life and known confounders for memory problems. Results After repeated invitations, the participation rate was 40% (N=794) of SARS-CoV-2 positive, 26% (N=7993) of negative, and 22% (N=4369) of untested randomly selected invitees. All participants completed the baseline questionnaire as a part of inclusion. The follow-up period was 248 days (SD=18) from baseline, and the follow-up questionnaire was completed by 75% of SARS-CoV-2 positive participants, 65% of negative participants, and 73% of untested randomly selected participants. At follow-up, 49 (11.5%) of the SARS-CoV-2 positive participants reported memory problems in contrast to 173 (4.1%) of the SARS-CoV-2 negative participants and 65 (2.4%) of the untested randomly selected participants. In a multivariate model, SARS-CoV-2 positivity remained strongly associated with reporting memory problems at eight months follow-up compared to the SARS-CoV-2 negative group (odds ratio (OR) 4.0, 95% confidence interval (CI) 2.8-5.2) and the untested group (OR 4.9, 95% CI 3.4-7.2). Compared to the other groups, SARS-CoV-2 positive participants also reported more concentration problems and a significant worsening of health compared to one year ago at follow-up. Feeling depressed, less energy, or pain were reported relatively equally by the different groups. Summary We find that 11.5% of COVID-19 patients experience memory problems eight months after the disease. SARS-CoV-2 is a new virus, and the long-term consequences of infections are therefore unknown. Our results show that a relatively high proportion of non-hospitalized COVID-19 patients report memory problems eight months after the disease.