Neurological conditions, such as Alzheimer’s disease, migraines, stroke and multiple sclerosis are now the leading cause of ill health and disability around the world, affecting 3.4 billion people, according to a new study.
The study, published Thursday in Lancet Neurology, found that these neurological conditions affected 43 per cent of the world population and caused more than 11 million deaths in 2021
“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 Valery Feigin, the director of Auckland University’s National Institute for Stroke and Applied Neuroscience in New Zealand.
“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,” he said in a Thursday media release.
The study, Global Burden of Disease, Injuries and Risk Factors Study (GBD) 2021, builds on previous versions to provide the “largest and most comprehensive analysis” of the prevalence and impact of nervous system disorders across countries worldwide from 1990 to 2021, it said. The analysis also broadened its scope by examining 37 neurological conditions, a substantial increase from the previous 15.
It found the number of people living with or dying from neurological conditions such as dementia and meningitis has risen 18 per cent over the last 30 years. The increase, the authors say, is largely due to an aging and growing population worldwide.
The top 10 contributors to neurological health loss in 2021 were stroke, brain injury, migraine, Alzheimer’s disease and other dementias, diabetic neuropathy (nerve damage), meningitis, epilepsy, neurological complications from preterm birth, autism spectrum disorder, and nervous system cancers.
Neurological consequences of COVID-19 ranked number 20, accounting for 2.48 million years of healthy life lost in 2021.
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The most prevalent neurological disorders in 2021 were tension-type headaches (around two billion cases) and migraines (about 1.1 billion cases). Diabetic neuropathy is the fastest-growing of all neurological conditions, the study found.
Over 80 per cent of neurological deaths and health loss occur in low and middle-income countries. This is largely attributed to disparities in access to treatment, the study found. High-income countries have up to 70 times more neurological professionals per 100,000 people compared to low and middle-income nations.
“This study should serve as an urgent call to action to scale up targeted interventions to allow the growing number of people living with neurological conditions to access the quality care, treatment and rehabilitation they need. It is more important than ever to ensure brain health is better understood, valued and protected, from early childhood to later life,” Dr. Tedros Adhanom Ghebreyesus, WHO Director-General, said in a Thursday press release.
What about Canada?
Joshua Armstrong, a research scientist at the Alzheimer Society of Canada (ASC), told Global News the Lancet study shows how far-reaching neurological disorders are and brings to light the different conditions impacting the nervous system. He stressed the need for a global focus to prevent and deal with these conditions as they increase in numbers.
In Canada, rates of neurological diseases like dementia are on the rise. With the rapid rise of Canada’s aging population, ASC projects the number of people living with dementia in the country will increase by 187 per cent by 2050.
Other neurological conditions, like strokes and Parkinson’s disease, are also increasing in the country, which has largely been attributed to a growing and aging population.
“We’re still seeing numbers of people living with dementia increase because of the aging population. More and more people over the age of 65 and over 75,” Armstrong said. “We expect that to continue to increase as the baby boomers get into their 80s and 90s.”
Apart from age, Armstrong said several other factors can increase the risk of neurological conditions. Environmental elements like pollution, smoking, and alcohol consumption, along with lifestyle factors such as obesity, exercise habits, and social isolation, all play significant roles.
What's next?
Understanding these risk factors is key to reducing the burden of some neurological disorders, the WHO says.
“Because many neurological conditions lack cures, and access to medical care is often limited, understanding modifiable risk factors and the potentially avoidable neurological condition burden is essential to help curb this global health crisis,” the Lancet study’s co-lead author, Dr. Katrin Seeher, a mental health specialist at WHO’s Brain Health Unit, said in a press release.
The study measured 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 suggested that modifying 18 risk factors over a person’s lifetime — most importantly high systolic blood pressure — could prevent 84 per cent of global rates from stroke.
Additionally, it suggested that controlling lead exposure could reduce the burden of intellectual disability by 63 per cent, while reducing high fasting plasma glucose to normal levels could reduce the burden of dementia by around 15 per cent.
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