Neurological conditions are now the leading cause of ill health and disability worldwide, surpassing cardiovascular disease and leading to a call for a change in health strategies, especially in lower and middle income countries, notes MedicalBrief.
In 2021, more than 3bn people worldwide were living with a neurological condition – the number of cases of diabetic neuropathy, for instance, having more than tripled globally since 1990, rising to 206m cases in 2021, according to a major study released by The Lancet Neurology.
The World Health Organisation (WHO) contributed to the analysis of the Global Burden of Disease, Injuries, and Risk Factor Study (GBD) 2021 data, which found that neurological conditions are now the leading cause of ill health and disability worldwide, and that the overall amount of disability, illness and premature death (known as disability-adjusted life years, DALYs) caused by neurological conditions, has increased by 18% since 1990.
More than 80% of neurological deaths and health loss occur in low- and middle-income countries, and access to treatment varies widely: high-income countries have up to 70 times more neurological professionals per 100 000 people than low- and middle-income countries.
“Neurological conditions cause great suffering to the individuals and families they affect, and rob communities and economies of human capital,” said Dr Tedros Adhanom Ghebreyesus, WHO Director-General.
“This study should serve as an urgent call to action to scale up targeted interventions to allow the growing number of people with these 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.”
The top 10 neurological conditions contributing to loss of health in 2021 were stroke, neonatal encephalopathy (brain injury), migraine, dementia, diabetic neuropathy (nerve damage), meningitis, epilepsy, neurological complications from preterm birth, autism spectrum disorder, and nervous system cancers.
Overall, neurological conditions cause more disability and health loss in men than in women, but there are some conditions, like migraine or dementia, where women are disproportionately affected.
Since 1990, the absolute number of individuals with, or dying from, neurological conditions has increased, while age-standardised DALY rates have dropped. This means that increases in absolute numbers are mainly driven by demographic change and people living longer.
Diabetic neuropathy was the fastest growing neurological condition. The number of people with diabetic neuropathy has more than tripled globally since 1990, rising to 206m cases in 2021. This increase is in line with the worldwide increase in diabetes.
Other conditions, such as neurological complications from Covid-19 (for example, cognitive impairment and Guillain-Barré syndrome) did previously not exist and now account for more than 23m cases.
At the same time, neurological burden and health loss due to other conditions decreased by 25% or more since 1990 as a result of improved prevention (including vaccines), care and research: tetanus, rabies, meningitis, neural tube defects, stroke, neurocysticercosis (parasitic infection that affects the central nervous system), encephalitis, and neonatal encephalopathy.
The study also examined 20 modifiable risk factors for potentially preventable neurological conditions like stroke, dementia and idiopathic intellectual disability.
Eliminating key risk factors – most importantly, high systolic blood pressure and ambient and household air pollution – could prevent up to 84% of stroke DALYs.
Similarly, preventing exposure to lead could reduce the burden of idiopathic intellectual disability by 63.1%, and reducing high fasting plasma glucose levels could reduce the burden of dementia by 14.6%. Smoking significantly contributed to stroke, dementia and multiple sclerosis risk.
More investments needed to improve treatment, care, quality of life
At the World Health Assembly in 2022, Member States adopted the Intersectoral global action plan on epilepsy and other neurological disorders 2022–2031 (IGAP) with an ambitious scope to address the long standing neglect of neurological disorders.
“This plan sets out a roadmap for countries to improve prevention, early identification, treatment and rehabilitation of neurological disorders. To achieve equity and access to quality care, we also need to invest in more research on risks to brain health, improved support for the healthcare workforce and adequate services,” said Dévora Kestel, director, WHO Department of Mental Health and Substance Use.
A ScienceAlert report says the main reason that nervous system conditions surpassed cardiovascular disease in the latest analysis was a recent World Health Organisation classification change that moved stroke into the neurological category, Steinmetz told AFP.
The massive number of healthy years lost from these conditions was partly because several can kill children under five, such trauma during birth leading to neonatal encephalopathy, asphyxia or meningitis, she said.
"Because deaths occur at a young age, this creates a large contribution to years of life lost," she added.
Children accounted for nearly a fifth of all healthy years lost, the study found.
'Growing very fast'
More than 11m people died from the 37 neurological conditions in 2021, according to study.
However cardiovascular disease remained the leading cause of death, killing 19.8m people worldwide in 2022, the IHME said last year.
The most common neurological disorders were tension headaches and migraines.
Study details
Global, regional, and national burden of disorders affecting the nervous system, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021
GBD 2021 Nervous System Disorders Collaborators
Published in The Lancet on 14 March 2024
Summary
Background
Disorders affecting the nervous system are diverse and include neurodevelopmental disorders, late-life neurodegeneration, and newly emergent conditions, such as cognitive impairment following COVID-19. Previous publications from the Global Burden of Disease, Injuries, and Risk Factor Study estimated the burden of 15 neurological conditions in 2015 and 2016, but these analyses did not include neurodevelopmental disorders, as defined by the International Classification of Diseases (ICD)-11, or a subset of cases of congenital, neonatal, and infectious conditions that cause neurological damage. Here, we estimate nervous system health loss caused by 37 unique conditions and their associated risk factors globally, regionally, and nationally from 1990 to 2021.
Methods
We estimated mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs), with corresponding 95% uncertainty intervals (UIs), by age and sex in 204 countries and territories, from 1990 to 2021. We included morbidity and deaths due to neurological conditions, for which health loss is directly due to damage to the CNS or peripheral nervous system. We also isolated neurological health loss from conditions for which nervous system morbidity is a consequence, but not the primary feature, including a subset of congenital conditions (ie, chromosomal anomalies and congenital birth defects), neonatal conditions (ie, jaundice, preterm birth, and sepsis), infectious diseases (ie, Covid-19, cystic echinococcosis, malaria, syphilis, and Zika virus disease), and diabetic neuropathy. By conducting a sequela-level analysis of the health outcomes for these conditions, only cases where nervous system damage occurred were included, and YLDs were recalculated to isolate the non-fatal burden directly attributable to nervous system health loss. A comorbidity correction was used to calculate total prevalence of all conditions that affect the nervous system combined.
Findings
Globally, the 37 conditions affecting the nervous system were collectively ranked as the leading group cause of DALYs in 2021 (443 million, 95% UI 378–521), affecting 3·40 billion (3·20–3·62) individuals (43·1%, 40·5–45·9 of the global population); global DALY counts attributed to these conditions increased by 18·2% (8·7–26·7) between 1990 and 2021. Age-standardised rates of deaths per 100 000 people attributed to these conditions decreased from 1990 to 2021 by 33·6% (27·6–38·8), and age-standardised rates of DALYs attributed to these conditions decreased by 27·0% (21·5–32·4). Age-standardised prevalence was almost stable, with a change of 1·5% (0·7–2·4). The ten conditions with the highest age-standardised DALYs in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer's disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications due to preterm birth, autism spectrum disorder, and nervous system cancer.
Interpretation
As the leading cause of overall disease burden in the world, with increasing global DALY counts, effective prevention, treatment, and rehabilitation strategies for disorders affecting the nervous system are needed.
Lancet PIIS1474442224000383
ScienceAlert – Major US Study Confirms a New #1 Cause of Disease Worldwide
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