Long-term brain fog and cognitive impairment in previously hospitalized COVID-19 patients

PLoS One. 2024 Aug 29;19(8):e0309102. doi: 10.1371/journal.pone.0309102. eCollection 2024.

Abstract

Objectives: Limited research exists on COVID-19 associated brain fog, and on the long-term cognitive and psychiatric sequelae in racially and ethnically diverse patients. We characterize the neuropsychological sequelae of post-acute COVID-19 in a diverse cohort and investigate whether COVID-19 clinical severity remains associated with brain fog and cognitive deficits approximately 2 years post infection.

Methods: A cross-sectional study of patients with a history of COVID-19 hospitalization (March-September 2020). COVID-19 clinical severity was indexed using the National Early Warning Score 2 and a comprehensive neuropsychological tele-battery was administered 2 years post discharge. Pearson's r correlations assessed association, while independent sample t-tests examined group differences. Significant outcomes were further analyzed using multiple regression and ANCOVAs, adjusting for key covariates.

Results: In 41 adult patients (19 female, 30 Hispanic, 13 Black, mean age of 65 (SD = 15), COVID-19 level of severity was associated with greater number of endorsed brain fog symptoms (Pearson's r = .34, 95% CI [.04, .59]), worse overall cognitive functioning (global cognition: r = -.36, 95% CI [-.61, -.05]) and reduced performance on an attention and working memory task (digit span backwards: r = -.41, 95% CI [-.66, -.09]) at 2-year follow-up. Brain fog symptoms most associated with COVID-19 severity included difficulty focusing (r = .46, 95% CI [.18, .67]), detached (r = .41, 95% CI [.12, .64]) and feeling sleepy (r = .40, 95% CI [.11, .63]). Patients' cognitive performance was generally below average (global cognition z-score: M = -.96, SD = .66), with group differences based on sex and ethnicity evidenced on individual cognitive tests.

Discussion: This study emphasizes the importance of continued research on the long-term effects of COVID-19 infection on neuropsychological outcomes, particularly among underrepresented, health-disparate groups. Greater understanding of these associations could improve detection and treatment of those at increased risk of cognitive decline or impairment.

MeSH terms

  • Aged
  • Brain / pathology
  • COVID-19* / complications
  • COVID-19* / epidemiology
  • COVID-19* / psychology
  • Cognitive Dysfunction*
  • Cross-Sectional Studies
  • Female
  • Hospitalization*
  • Humans
  • Male
  • Middle Aged
  • Neuropsychological Tests*
  • SARS-CoV-2 / isolation & purification
  • Severity of Illness Index

Grants and funding

The author(s) received no specific funding for this work.