Long COVID affects millions of people worldwide, with symptoms persisting for months or even years after an initial infection that may have been mild. One of the most commonly reported and feared symptoms is “brain fog,” a term used to describe problems with memory, concentration, processing speed and executive function. These challenges can make everyday tasks, work, education and social relationships difficult.
However, the new study reveals that reports of brain fog and other neurological symptoms are far from uniform across countries.
Striking Differences by Geography
The study, published in Frontiers in Human Neuroscience, involved 3,157 participants from four countries—the United States, Colombia, Nigeria and India. All participants were experiencing lingering neurological symptoms following COVID-19 infection and were grouped into those who had been hospitalized and those who had not.
Among non-hospitalized patients, 86 percent of participants in the United States reported brain fog. This figure dropped to 63 percent in Nigeria and 62 percent in Colombia. In contrast, only 15 percent of patients in India reported experiencing the symptom.
Similar disparities were observed for anxiety and depression. In the US, 73 percent of patients reported these symptoms, compared with 40 percent in Colombia, 17 percent in India, and just 6 percent in Nigeria.
Not About Disease Severity
The researchers stress that the findings do not suggest that long COVID is more severe in some countries than others. Instead, they point to differences in healthcare access, health literacy, cultural attitudes and stigma surrounding mental and cognitive health as likely explanations.
Senior author Dr Igor Koralnik noted that in countries such as Nigeria and India, cultural denial of mood disorders, stigma, religious and belief systems, and limited access to mental health professionals may lead to underreporting of symptoms. He added that a lack of perceived treatment options may further discourage patients from identifying or disclosing cognitive and psychological difficulties.
Implications for Care and Research
The authors describe the research as the first cross-continental comparison of neurological symptoms in long COVID. They say the findings highlight the need for culturally sensitive screening tools and more equitable long-term healthcare for long COVID patients worldwide.
Building on the results, the research team is now testing cognitive rehabilitation programmes—already shown to benefit patients in the US—in Nigeria and Colombia, with the aim of expanding effective treatment options.
The researchers say future efforts should focus on improving awareness, reducing stigma, and ensuring that long COVID patients everywhere receive appropriate diagnosis and care.