Long COVID Brain Fog Far More Common in US than India, Other Nations
Large study of patients in the US, Colombia, Nigeria and India finds symptom burden highest in high-income countries

Patients with long COVID-19 in the US report far higher rates of brain fog, depression and cognitive symptoms than patients in countries such as India and Nigeria, according to a large international study led by Northwestern Medicine.
The authors note that higher reported symptom burden in the US may reflect lower stigma and greater access to neurological and mental health care, rather than more severe disease.
The study, the first cross-continental comparison of long COVID neurological manifestations, tracked more than 3100 adults with long COVID evaluated at academic medical centres in Chicago; Medellín, Colombia; Lagos, Nigeria; and Jaipur, India.
Among patients who were not hospitalised during their COVID infections (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: Nearly 75% of non-hospitalised patients in the US reported symptoms of depression or anxiety, compared with only 40% in Colombia and fewer than 20% in Nigeria and India.
“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,” said Dr Igor Koralnik, senior study author and chief of neuro-infectious disease and global neurology at Northwestern University Feinberg School of Medicine.
“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.”
The study was published in Frontiers in Human Neuroscience.
Additional key findings
- Brain fog, fatigue, myalgia (muscle pain), headache, dizziness and sensory disturbances (such as numbness or tingling) were the most common neurological symptoms across all countries
- Insomnia was reported by nearly 60% of non-hospitalised US patients, compared with roughly one-third or fewer of patients in Colombia, Nigeria and India
- Statistical clustering showed clear separation between high- and upper-middle-income (US, Colombia) and lower-middle-income (Nigeria, India) countries
Building on this work, Koralnik and his international collaborators are now studying cognitive rehabilitation treatments for long COVID brain fog in Colombia and Nigeria, using the same protocols developed for patients treated at the Shirley Ryan AbilityLab in Chicago.
Source: Northwestern University



