Identify the leading cause of disability and premature death worldwide

A study shows that more than 40% of people around the world live with some type of brain condition that causes disability and death.

In 2021, 3.4 billion people worldwide suffered from neurological conditions such as Alzheimer's disease, stroke and migraines, a much larger number than previously thought, making these conditions the leading cause of ill health and disability globally.

Scientists said an aging global population and increased exposure to environmental, health and lifestyle risk factors are likely to be behind these cases.

Data now indicate that total cases - the leading cause of disability, disease and premature death - have increased globally by 18% in the past three decades, from 1990 to 2021.

Neurological conditions also include meningitis, brain injury, and nerve damage, which can be caused by diabetes.

Diabetic neuropathy, where diabetes causes nerve damage, turns out to be the fastest growing of all neurological conditions.

Dr Lian Ong from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington in the US, a co-author of the study, said: “The number of people with diabetic neuropathy has more than tripled globally since 1990, rising to 206 million in 2021. This is in line with the increase in the prevalence of diabetes globally.”

The study, published in The Lancet Neurology, looked at how rates of dementia and 36 other neurological conditions around the world have changed over time.

The researchers looked at data on cases, deaths and disability in 204 countries around the world over a period of 31 years.

They used a measure known as DALYs to evaluate years of healthy life lost due to disability or premature death.

They found that over the past 31 years, the total amount of healthy life lost due to neurological conditions has risen from about 375 million years in 1990, to 443 million years in 2021.

This disproportionately affected poorer countries, partly due to birth-related complications and infections affecting newborns and young children, said Dr Tarun Dua, of the WHO Brain Health Unit, who co-authored the study.

The researchers said that since many of these cases lack a cure, prevention should be a top priority.

According to the team's analysis, modifying 18 risk factors over the course of a person's life, the most important of which is high blood pressure, can prevent 84% of disabilities, diseases and premature deaths in the world due to stroke.

In addition, the researchers said that lowering high blood sugar levels to normal could reduce the burden of dementia by about 15%.