“Manifestation of cognitive dysfunction is present regardless of illness severity,” Dr. Antonio D. Ligsay from the College of Science - University of Santo Tomas, a member of the researcher team who conducted the systematic review on “Clearing the Fog: A Systematic Review on Cognitive Dysfunction in COVID-19, stated.


The review article presented evidences regarding the association between COVID-19 and cognitive dysfunction, and the most frequent cognitive impairment are attention, memory, and executive function or higher-level cognitive skills, used to control and coordinate other cognitive abilities and behaviors in COVID-19 patients.

Cognitive dysfunction or “brain fog” as it is known can manifest as confusion, difficulty finding the appropriate words, disorientation, memory problems, altered mental status, and trouble concentrating.

The systematic review, which was carried out in 2021, involved the identification of 289 studies through a comprehensive search in databases, of which a total of 85 full-text studies were assessed for eligibility.

After critical appraisal, 13 studies were included in the final systematic review which examined the association between COVID-19 and cognitive dysfunction, including the link between the severity of COVID-19 and the occurrence of cognitive impairment and the potential abnormal mechanisms related to brain fog among COVID-19 patients. 

The participants included in the assessed studies were all greater than sixteen years old, and all were diagnosed with COVID-19 infection.

All included studies that utilized the Montreal Cognitive Assessment (MoCA) test showed mild cognitive impairment (MCI) following COVID-19 infection. Among the cognitive domains, attention, executive function, and memory are most likely to be impaired. Increasing evidence also suggests that cognitive dysfunction due to COVID-19 is manifested across disease severity ranging from asymptomatic to critical illness. The interplay between physical and cognitive impairments may lead to functional problems inhibiting health-related standards of life.

Findings from this research may help re-evaluate the impact of the virus and the results may help in earlier treatment, allowing physicians and clinicians to manage the neurological manifestation effectively. The research team added that the knowledge gained from this study may be also used to improve the implementation of comprehensive treatment modalities and rehabilitation throughout the COVID-19 care continuum to remove such barriers and restore the meaningful lives of patients brought about by brain fog.

The team of researchers are from the University of Santo Tomas; University of the Philippines Manila; and St. Luke’s Medical Center.

The full report on this research will appear in the Philippine Journal of Science (PJS), the oldest science journal in the country, on December 2022 Issue-Part A. PJS is published by the Department of Science and Technology-Science and Technology Information Institute (DOST-STII). (Geraldine Bulaon-Ducusin, DOST-STII).