The Link Between “Brain Fog” and Long COVID

For COVID-19 patients, experiencing cognitive deficits or “brain fog” in the first 4 weeks of infection may be related to longstanding COVID, according to the original investigation published in The Open JAMA Network.

Researchers from UCLA conducted a prospective cohort study of 766 patients with COVID-19 to describe the characteristics of patients with perceived cognitive deficits in the first 4 weeks after COVID-19 infection and the relationship between these deficits and long COVID. Patients were enrolled in the study between April 2020 and February 2021 after laboratory-confirmed COVID-19 infection.

The study authors say such neuropsychiatric symptoms are common in both acute COVID-19 and longstanding COVID, but the link between this deficit — called “brain fog” — and legacy COVID is currently unknown. Brain fog also affects all age groups, the study authors added, and neurocognitive symptoms can include memory problems, difficulty concentrating, difficulty focusing and PTSD.

The participants were followed up using a nurse-administered questionnaire by telephone after 30-, 60-, and 90 days after discharge from the hospital (or in the case of non-hospitalized patients, from the date of the first positive COVID-19 test). The questionnaire asked participants whether they felt their health had returned to normal, whether they were able to complete strenuous activities (such as running), moderate activities (such as moving tables, climbing stairs, etc.), and bathing and dressing independently.

The study authors noted that patients were also asked about symptoms in the previous 4 weeks such as: fever, chills, or night sweats; loss of smell or taste; fatigue; hard to breathe; chest pain; numbness or tingling; nausea, vomiting or diarrhea; Muscle ache; and rash.

Finally, the questionnaire asked participants if they had difficulty organizing things, had trouble concentrating on activities such as watching television or reading a book, and whether they had forgotten what they had talked about during telephone conversations during the previous 4 weeks. Participants can answer “never”, “rarely”, “sometimes”, “often”, and “almost always”.

At baseline, the researchers observed that 23.5% of participants reported being able to complete strenuous activities, and 48% reported being able to complete moderate activities.

Additionally, 64% of participants reported no perceived cognitive deficits on the 3 items of the questionnaire. About a third of patients reported difficulty keeping things organized, and a third reported difficulty concentrating on activities, while a quarter reported forgetting what they had talked about during a phone call. The most common symptoms of acute COVID-19 so far are fatigue, shortness of breath and muscle aches, the study authors noted.

For longstanding COVID patients, the study authors found that patients who reported cognitive impairment were more likely to report prolonged COVID symptoms at 60 and 90 days compared to those who did not perceive any cognitive impairment. There were 233 patients who reported prolonged COVID symptoms at 60 and 90 days, and half reported cognitive deficits at 30 days. In comparison, of 543 patients who did not report symptoms of old COVID at 60 or 90 days, only 29% reported cognitive deficits at the 30-day survey.

“In a longitudinal cohort study of patients with COVID-19 in 1 healthcare system, we found an association between perceived cognitive deficits early in the disease and old COVID, indicating a direction for exploring the underpinnings of old COVID,” the study authors concluded.

For further reading on COVID-19 and brain fog, see past reports from Transmission: “COVID-19 Infection Aggravates Dementia.”