Long-COVID patients in the United States report markedly higher rates of neurologic symptoms like brain fog and depression than those in lower-income nations, according to a large analysis led by a team from Northwestern University and published this week in Frontiers in Human Neuroscience.
For one of the first cross-continental comparisons of neurologic symptoms in long-COVID patients, the researchers tracked more than 3,100 adults with long COVID at medical centers in Chicago; Medellin, Colombia; Lagos, Nigeria; and Jaipur, India.
86% in US report brain fog, versus 15% in India
Among long-COVID patients who were not hospitalized during their initial infection (most participants), 86% of those in the United States reported brain fog, compared with 62% in Colombia, 63% in Nigeria, and 15% in India. Symptoms of anxiety or depression were reported by 70% of US participants, compared with roughly 68% in Colombia and less than 20% in Nigeria and India.
The team found symptom patterns clustered by income level, with high-income countries (like the United States) and upper-middle–income countries (like Colombia) grouped together with higher rates of reported symptoms, and lower-middle–income countries (Nigeria and India) forming a separate group with lower rates of reported symptoms.
These disparities likely suggest social and cultural differences in how long COVID is experienced and reported rather than differences in the biology of the virus. They may also reflect differences in access to health care, the authors said.
“It is culturally accepted in the U.S. and Colombia to talk about mental health and cognitive issues, whereas that is not the case in Nigeria and India,” senior author Igor Koralnik, MD, chief of neuro-infectious disease and global neurology at Northwestern University’s Feinberg School of Medicine, said in a news release.
“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.”
Roughly 18% of all adults have had long COVID
Across all four countries, the most frequently reported neurologic symptoms were brain fog, fatigue, muscle pain, headache, dizziness, and sensory disturbances such as numbness or tingling.
Insomnia was also common, particularly among non-hospitalized US patients, 64% of whom reported sleep problems. Less than half of patients in Colombia (46%), Nigeria (26%), and India (12%) reported sleep problems. Symptoms can persist for months or years after an acute COVID infection and affect multiple organ systems.
Long COVID has emerged as a major public health challenge since the pandemic began, the researchers said. A survey conducted between June 2022 and September 2024 by the National Center of Health Statistics estimated that nearly 18% of all adults ever have experienced long COVID.
Neurologic symptoms of long COVID are an underrecognized contributor to decreased quality of life. They also take an economic toll, affecting “young and middle-aged adults in their prime, causing significant detrimental impact on the workforce, productivity and innovation all over the world,” write the authors.
“Our findings highlight the need for culturally adapted screening and diagnosis of Neuro-PASC [neurologic post-acute sequelae of SARS-CoV-2 infection] worldwide, and for the integration of post-COVID care in healthcare systems to enable long term follow-up and therapeutic interventions,” they conclude.
