American patients who have had COVID-19 report “brain fog,” depression, and mental impairments significantly more often compared to those who recovered in India or Nigeria. This is the conclusion reached by the authors of a major international study overseen by experts from Northwestern Medicine. The work was published in the journal FHN.
This research marks the first cross-continental comparison of neurological manifestations of COVID. Over 3,100 adult patients, examined at academic medical centers in the USA, Colombia, Nigeria, and India, were included in the study. The analysis encompassed both hospitalized and non-hospitalized individuals who contracted COVID-19 between 2020 and 2025.
Among those who were not treated as inpatients, 86% of US subjects reported experiencing “brain fog.” In Nigeria, this figure stood at 63%, in Colombia at 62%, whereas in India, it was only 15%. A comparable disparity was evident concerning psychological symptoms: nearly 75% of American patients exhibited depression or anxiety, contrasting with about 40% in Colombia, and less than 20% in both Nigeria and India.
The study’s originators, specialists from Northwestern University’s Feinberg School of Medicine, attribute the higher symptom burden observed in the US not to inherently more severe illness patterns, but rather to cultural and systemic variances.
In the United States and Colombia, expressing concerns about mental well-being and cognitive difficulties is generally accepted, whereas in Nigeria and India, attitudes toward such symptoms differ. Religious beliefs, lower levels of health literacy, and a shortage of mental health professionals also play a role.
Across all nations, the most frequent neurological complaints were “brain fog,” fatigue, muscle and headaches, dizziness, numbness, and tingling sensations. Approximately 60% of non-hospitalized patients in the US complained of insomnia, while in Colombia, Nigeria, and India, fewer than one-third reported this issue.
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