Long COVID Brain Symptoms Differ Widely Between Countries

Long COVID continues to confound doctors worldwide. Many people recover from a COVID infection but find, months afterwards, that they still have difficulties with memory, concentration, sleep or mood.

These neurological symptoms can disrupt education, employment and everyday activities more severely than persistent breathing difficulties.

Northwestern Medicine researchers, collaborating with teams in four countries, now report that the frequency with which people disclose these brain-related symptoms differs greatly between nations. The disparity is evident even where the virus spread in comparable patterns.

Long COVID brain fog differs

The researchers assessed more than 3,100 adults with long COVID in four countries: patients in Chicago, United States; Medellín, Colombia; Lagos, Nigeria; and Jaipur, India.

Although most participants had not needed hospital treatment during their initial infection, every participant continued to experience neurological symptoms months after recovery.

Brain fog was among the complaints reported most frequently, encompassing difficulties with memory, concentration and clear thought.

Of non-hospitalised COVID patients in the United States, 86 percent reported brain fog. Comparable symptoms were reported by around six in ten patients in Colombia and Nigeria, compared with only about 15 percent in India.

These variations do not mean that illness was less severe in India or Nigeria. SARS-CoV-2 variants circulated internationally in broadly similar patterns, and biology alone cannot account for gaps of this scale. Instead, the researchers identify social, cultural and healthcare influences as probable reasons for the differences.

Mood symptoms vary by country

Depression and anxiety were reported much more frequently in higher-income settings. Almost three-quarters of patients in the United States described mood-related symptoms, while levels in Colombia were moderate. Rates reported in Nigeria and India were substantially lower.

Sleep difficulties showed the same general trend. More than half of U.S. patients experienced insomnia, whereas it was reported much less often in the other locations.

Taken together, the patterns indicate differences in recognising and reporting symptoms, rather than genuine differences in whether the condition is present.

“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,” said Dr. Igor Koralnik, the study’s lead author.

He said that stigma, misunderstandings, religious beliefs, low health literacy and cultural denial of mood symptoms can all lead to biased reporting. These issues are compounded by a lack of mental health professionals and few treatment options perceived to be available.

In places where discussing mental health openly is supported, people are more likely to report symptoms. In settings dominated by stigma and silence, distress may instead be expressed through physical pain or fatigue.

Long COVID brain biology is similar

Despite the differences in reporting, patients in every region shared common symptoms. Worldwide, people experienced fatigue, muscle pain, dizziness, headaches, numbness, tingling and brain fog. This commonality suggests shared biological mechanisms.

Persistent immune activation, low-grade inflammation and stress affecting the nervous system are likely to cause long COVID brain symptoms across populations. Differences in viral behaviour between regions are not large enough to explain the reporting disparities.

Objective cognitive assessments reinforce this conclusion. Problems with memory and attention occurred in every region, although higher-income regions recorded greater rates of abnormal test results.

Lower-income regions had fewer abnormal results, in part because simpler screening methods may fail to identify subtle impairments.

Healthcare access changes visibility

Availability of healthcare is also important. Neurology services, mental health screening and follow-up appointments are more widely available in wealthier settings. Increased testing produces increased detection, while restricted access limits diagnoses even when symptoms continue.

Non-hospitalised patients accounted for most long COVID cases in each country. A mild initial illness did not protect people from long-term brain problems. Previous hospital care raised the symptom burden, but it did not solely determine risk.

Gender and access to care also shaped the findings. Women made up most non-hospitalised cases in the United States and Colombia.

Men accounted for most of the Indian samples. In parts of South Asia, substantial barriers still prevent women from accessing healthcare, likely lowering clinic attendance rather than reducing disease burden.

Social factors outweigh geography

Statistical analysis placed the United States and Colombia in one group, and Nigeria and India in another. Symptom burden corresponded more closely with income level than with geography. This clustering favours a social, rather than viral, explanation.

Neurological examinations identified memory loss and sensory changes in all regions, but detection rates varied considerably. Long COVID is present worldwide, though recognition is inconsistent.

When long COVID stays hidden

Millions of people could be living with long COVID without receiving a diagnosis or care. Undetected brain symptoms can still impair productivity, learning and quality of life.

Health systems around the world may underestimate the burden of long COVID in resource-limited settings.

The researchers advocate culturally adapted screening tools and common testing standards. Improved tools could uncover hidden illness and help inform long-term care planning.

As the study’s authors emphasized, long COVID affects young and middle-aged adults in their prime, causing significant detrimental impacts on the workforce, productivity, and innovation worldwide.