Brain Drain: Experts warn neurological disorders brutalizing billions

By James Gamble via SWNS

Neurological conditions including stroke and dementia now affect nearly half the world's population, a shocking new study has found.

Research shows nervous system conditions now affect at least 3.4 billion people and are the leading cause of ill health and disability worldwide.

The new study - the most comprehensive of its kind ever undertaken - also shows neurological conditions were responsible for the loss of 443 million years of healthy life in 2021 alone due to illness, disability, and premature death.

The study's authors warned that the enormous public health impacts of these often preventable conditions highlight the urgency for neurological health to be made a global public health priority.

Across the world, the number of people living with - or dying from - neurological conditions such as stroke, dementia, neonatal brain injury and meningitis has risen dramatically over the past 30 years.

This is due to the growth and aging of the global population and an increase in exposure to environmental, metabolic and lifestyle risk factors.

In 2021, 3.4 billion people - around 43 percent of the global population - experienced a nervous system condition, according to a new analysis from the Global Burden of Disease, Injuries, and Risk Factors Study (GBD) 2021.

The analysis, published in The Lancet Neurology journal, suggests that the overall amount of disability, illness, and premature death - a measurement known as disability-adjusted life years (DALYs) - caused by neurological conditions increased by nearly a fifth (18%) over the past 31 years, rising from around 375 million years of healthy life lost in 1990 to 443 million years in 2021.

This figure is on the rise largely due to aging and growing populations worldwide.

However, if this demographic impact is removed through age standardization, rates of DALYs and deaths caused by neurological conditions have declined by around a third (27 per cent and 34 per cent respectively) worldwide since 1990.

This is largely explained as being a result of better awareness, vaccination, and global prevention efforts for some conditions such as tetanus (93 percent decrease in age-standardized rates of DALYs), meningitis (62 percent decrease), and stroke (39 percent decrease).

The study showed the top ten contributors to neurological health loss in 2021 were stroke, neonatal encephalopathy (brain injury), migraine, dementias such as Alzheimer's, diabetic neuropathy (nerve damage), meningitis, epilepsy, neurological complications from preterm birth, autism spectrum disorder and nervous system cancers.

Neurological consequences of COVID-19 (cognitive impairment and Guillain-Barré syndrome) ranked 20th, accounting for 2.48 million years of healthy life lost in 2021.

The most prevalent neurological disorders in 2021 were tension-type headaches (around two billion cases) and migraines (around 1.1 billion cases), whilst diabetic neuropathy is the fastest-growing of all neurological conditions.

Dr. Liane Ong, a co-senior author of the study from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, explained: "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 global prevalence of diabetes.”

Lead author Dr. Jaimie Steinmetz, also from IHME, said: “Every country now has estimates of their neurological burden based on the best available evidence.

“As the world’s leading cause of overall disease burden, and with case numbers rising 59 percent globally since 1990, nervous system conditions must be addressed through effective, culturally acceptable, and affordable prevention, treatment, rehabilitation, and long-term care strategies."

The study additionally revealed striking differences in nervous system burden between world regions and national income levels.

In high-income Asia Pacific and Australasia – regions with the best neurological health – the rate of DALYs and deaths were under 3,000 and 65 per 100,000 people respectively in 2021.

Stroke, migraine, dementia, diabetic neuropathy, and autism spectrum disorders accounted for most health loss in this region.

In contrast, in the worst-off regions of western and central sub-Saharan Africa, the rate of DALYs and deaths were up to five times higher (over 7,000 and 198 per 100,000 people respectively) in 2021, with stroke, neonatal encephalopathy (brain injury), dementia and meningitis the biggest contributors to years of healthy life lost.

"Nervous system health loss disproportionately impacts many of the poorest countries partly due to the higher prevalence of conditions affecting neonates and children under 5, especially birth-related complications and infections,” said Dr. Tarun Dua, Unit Head of the WHO’s Brain Health unit and one of the co-senior authors of the study.

“Improved infant survival has led to an increase in long-term disability, while limited access to treatment and rehabilitation services is contributing to the much higher proportion of deaths in these countries.”

Study researchers quantified the proportion of nervous system burden that was potentially preventable by eliminating known risk factors for stroke, dementia, multiple sclerosis, Parkinson’s disease, encephalitis, meningitis, and intellectual disability.

The analysis suggests modifying 18 risk factors over a person’s lifetime - most importantly high systolic blood pressure (57 percent of DALYs) - could prevent 84 percent of global DALYs from strokes.

Estimates also suggest that controlling lead exposure could reduce the burden of intellectual disability by more than half (63 percent), and reducing high fasting plasma glucose to normal levels could reduce the burden of dementia by around 15 percent.

Senior author Dr. Valery Feigin, Director of Auckland University’s National Institute for Stroke and Applied Neuroscience in New Zealand said: “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.

"For many other conditions, there is no cure, underscoring the importance of greater investment and research into novel interventions and potentially modifiable risk factors.”