Why US leads world in long COVID-19 related brain fog

By Stephen Beech

Brain fog linked to long COVID-19 is far more common in people living in high-income countries, according to new research.

The study of more than 3,100 patients in the United States, Colombia, Nigeria and India is first to compare long COVID brain symptoms across continents.

The findings showed that brain fog affected 86% of non-hospitalized American patients, compared with 15% in India

Symptom patterns clustered by income level rather than geography, say scientists.

Patients with long COVID in the US reported far higher rates of brain fog, depression and cognitive symptoms than patients in the other countries covered by the study.

The higher reported symptom burden in the United States may reflect lower stigma and greater access to neurological and mental health care, rather than more severe disease, according to the research team.

The study, led by scientists at Northwestern Medicine, tracked more than 3,100 adults with long COVID evaluated at academic medical centres in Chicago; Medellín, Colombia; Lagos, Nigeria; and Jaipur, India.

Among patients who were not hospitalized while infected with COVID-19, the majority in the study, 86% in the US reported brain fog, compared with only 63% in Nigeria, 62% in Colombia and 15% in India.

Rates of psychological distress showed a similar pattern, according to the findings published in the journal Frontiers in Human Neuroscience.

Nearly 75% of non-hospitalised American patients reported symptoms of depression or anxiety, compared with only 40% in Colombia and less than 20% in Nigeria and India.

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Study senior author Dr. Igor Koralnik said: “It is culturally accepted in the US and Colombia to talk about mental health and cognitive issues, whereas that is not the case in Nigeria and India.

“Cultural denial of mood disorder symptoms as well as a combination of stigma, misperceptions, religiosity and belief systems, and lack of health literacy may contribute to biased reporting.

"This may be compounded by a dearth of mental health providers and perceived treatment options in those countries.”

Researchers also found that brain fog, fatigue, muscle pain, headache, dizziness and sensory disturbances - such as numbness or tingling - were the most common neurological symptoms across all four countries.

Insomnia was reported by nearly 60% of non-hospitalized American patients, compared with around a third or fewer of patients in Colombia, Nigeria and India.

Dr. Koralnik says long COVID affects millions of people worldwide and is characterised by symptoms persisting for weeks or even years after an acute COVID-19 infection.

Previous studies estimate that between 10% and 30% of adults infected with COVID-19 develop long-term symptoms, with neurological and cognitive complaints among the most common.

Dr. Koralnik, chief of neuro-infectious disease and global neurology at Northwestern University Feinberg School of Medicine, says long COVID-19 “affects young and middle-aged adults in their prime, causing significant detrimental impact on the workforce, productivity and innovation all over the world.”

He said American patients consistently reported the highest burden of neurological and psychological symptoms, which “affected their quality of life and ability to work.”

Dr Koralnik added: "The findings underscore the need for culturally sensitive screening tools and diagnostic approaches for long COVID, as well as healthcare systems equipped to support long-term follow-up and treatment."

Dr. Koralnik and his colleagues are now studying cognitive rehab treatments for long COVID-19 brain fog in Colombia and Nigeria, using the same protocols developed for patients treated at the Shirley Ryan AbilityLab in Chicago.