A patient is prepared for functional near-infrared spectroscopy, which assesses brain activation during motion capture, at the Motion Analysis Lab at the National Institutes of Health. Photo courtesy of National Institutes of Health
March 14 (UPI) -- Neurological conditions that affect 3.4 billion people are the No. 1 cause of ill health and disability around the world, ahead of cardiovascular diseases, a new study released Thursday shows.
In what researchers say is the most comprehensive study to date, systematic analysis of data from a 2021 study suggests that overall disability, illness and premature death from neurological conditions rose by 18% from 375 million years of healthy life lost in 1990 to 443 million years in 2021.
Published in The Lancet, the study by scientists at the University of Washington, Aukland University and the WHO Brain Health Unit, found the burden imposed by 37 conditions was much greater than previously understood, affecting 43% of the global population, according to a news release.
These include stroke, brain injury, migraine, Alzheimer's disease and other dementias, and nerve damage, the researchers said.
Of the 443 million years lost, neurodevelopmental and pediatric conditions were estimated to account for almost one-fifth of the total, equivalent to 80 million years of healthy life lost in 2021.
The authors attributed the nervous system epidemic principally to the growth and aging of the global population and increased exposure to environmental, metabolic and lifestyle risk factors.
However, the burden is not evenly distributed geographically, with central and western sub-Saharan Africa carrying the heaviest load with the least facilities and resources, while Asia Pacific and Australasia had the lowest burden but were much better positioned to cope, the researchers found.
Asia Pacific-Australasia's rate of disability-adjusted life years and deaths came mainly from stroke, migraine, dementia, diabetic neuropathy and autism disorders. In sub-Saharan Africa, where afflictions were five times higher, stroke, neonatal encephalopathy, dementia and meningitis were the biggest contributors.
The medical systems of high-income countries have 70 times as many neuro-specialists per 100,000 population as developing countries. About 25% of countries have a budget specifically to treat neurological conditions and about half have clinical guidelines, the authors said.
They called for neurological health to be made a global public health priority to mitigate the enormous and growing impact.
"Every country now has estimates of their neurological burden based on the best available evidence," said lead author Dr Jaimie Steinmetz, of the Health Metrics and Evaluation Institute at the University of Washington.
"As the world's leading cause of overall disease burden, and with case numbers rising 59% globally since 1990, nervous system conditions must be addressed through effective, culturally acceptable and affordable prevention, treatment, rehabilitation, and long-term care strategies," he said.
The top contributors to neurological health loss in 2021 were stroke, neonatal encephalopathy, migraine, dementia conditions including Alzheimer's, diabetic neuropathy, meningitis, epilepsy, neurological complications from preterm birth, autism spectrum disorder and nervous system cancers.
Cognitive impairment and Guillain-Barre syndrome resulting from COVID-19 accounted for 2.48 million years of healthy life lost in 2021, followed by tension headaches and migraines, with around 2 billion and 1.1 billion cases, respectively, but the fastest growing area of concern was nerve damage from diabetes.
"The number of people with diabetic neuropathy has more than tripled globally since 1990, rising to 206 million in 2021," said co-senior author Dr Liane Ong from the health institute at the University of Washington.
"This is in line with the increase in the global prevalence of diabetes," Ong said.
However, controlling for age and other demographic impacts, global rates of disability-adjusted life years and deaths from neurological illness are down 27% and 34%, respectively, worldwide since 1990, mostly due to better awareness, vaccination and global prevention efforts, with outstanding progress achieved for some conditions, the researchers said.
Disability-adjusted life years from tetanus fell 93%, 62% for meningitis and 39% for stroke, the data showed.
Women were found to suffer fewer neurological conditions than men globally -- 5,186 compared with 6,101 per 100,000 people -- but women were impacted more by COVID-19, multiple sclerosis and migraine, while attention deficit hyperactivity and autism spectrum disorders and traumatic brain injury were twice as high in men.
"The worldwide neurological burden is growing very fast and will put even more pressure on health systems in the coming decades," said co-senior author Dr. Valery Feigin, director of Auckland University's National Institute for Stroke and Applied Neuroscience.
"Yet, many current strategies for reducing neurological conditions have low effectiveness or are not sufficiently deployed, as is the case with some of the fastest-growing but largely preventable conditions like diabetic neuropathy and neonatal disorders," Feigin said.
"For many other conditions, there is no cure, underscoring the importance of greater investment and research into novel interventions and potentially modifiable risk factors."
The study was funded by the Bill and Melinda Gates Foundation.
