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Neurologic Diseases Found to Be the Largest Cause of Disability Worldwide



CONTRIBUTIONS OF VARIOUS neurologic disorders to the overall burden from neurological disorders in 2015.

In an analysis of data for 195 countries, the Global Burden of Disorders Study Group found that neurological disorders caused 250.7 million disability-adjusted life years (DALYs) in 2015, an increase of 7.4 percent from 1990. Stroke was reported to be one of the leading causes of DALYs worldwide.

Neurological diseases are the world's largest cause of disability-adjusted life years (DALYs), or years of healthy life lost to due to death or disability, according to a systematic analysis performed for the Global Burden of Disease Study 2015, the most current overview of the way neurological diseases are affecting people around the world.

Neurologists specializing in global health told Neurology Today the analysis brings into sharp focus the immense burden of neurological disorders around the globe. Importantly, they said, its bold statement should help free up resources for neurological care, while the country-by-country breakdown — data for 195 nations are included — will help guide the way forward in addressing the problems faced around the world.

Published in the September 17 online edition of Lancet Neurology, the analysis includes data for disease groupings broken down from a myriad of perspectives: nation, socio-demographics, age, gender, and in proportion to one another.


The analysis is largely a story about the devastating impact of stroke — no longer categorized as a cardiovascular disorder but as neurological by the World Health Organization (WHO) and the Global Burden of Disease study group.

With stroke included for the first time in such a broad and detailed analysis, neurological disorders caused 250.7 million DALYs in 2015, an increase of 7.4 percent from 1990.

“The most surprising findings were the amount of increase in the burden from 1990 to 2015 in virtually all countries of the world and that neurological disorders are now the leading causes of disability among all groups of diseases,” said Valery Feigin, MD, PhD, a lead author of the analysis and director of the National Institute for Stroke and Applied Neurosciences at Auckland University of Technology in New Zealand.

Neurological disorders caused 9.4 million deaths in 2015, up 36.7 percent from 1990, making them the second-leading cause of mortality around the world. Cardiovascular disorders, even without stroke, continue to be the leading mortality cause.

The increase in years of healthy life that have been lost among the world's population due to neurological disorders comes despite decreases in rates of DALYs per 100,000 when they are adjusted for age. This age-adjusted rate fell by 29.7 percent from 1990 to 2015.

“In terms of absolute number of people affected by neurological disorders, most of the increase in the burden was associated with aging of the population and population growth,” the study authors wrote.


DR. JEROME H. CHIN: “Despite improvements in the prevention and treatment of some neurological disorders, for example, stroke, meningitis, and epilepsy, the absolute global burden has increased as a result of population expansion and increasing life expectancies.”

The researchers found that stroke accounted for 118.6 million DALYs in 2015, an increase of 21.7 percent from 1990, and 6.3 million deaths, an increase of 36.4 percent.

Globally, stroke accounted for the largest proportion of DALYs, at 47.3 percent of the total, and deaths, at 67.3 percent.


Migraine, meningitis, and Alzheimer's disease and other forms of dementia accounted for the next highest proportion of DALYs. The second largest contributor to deaths from neurological disorders was Alzheimer's disease and other dementia causes, with the other causes accounting for a much smaller proportion.

Stroke was also found to be the leading cause of age-adjusted DALY rates in 18 of 21 Global Burden of Disease regions.

The lowest age-adjusted DALY rates were seen in high-income countries, while the highest rates were seen in Afghanistan, Central African Republic, Guinea-Bissau, Kiribati, and Somalia. Communicable neurological diseases, such as meningitis, were a big contributor to the disease burden in low-income regions, while they ranked very low in high-income regions.


Jerome H. Chin, MD, PhD, MPH, FAAN, chair of the International Subcommittee of the AAN and adjunct professor of neurology at New York University, said the report illustrates how the burden of neurological disorders is “substantial, varied, and growing.”

“Despite improvements in the prevention and treatment of some neurological disorders, for example, stroke, meningitis, and epilepsy, the absolute global burden has increased as a result of population expansion and increasing life expectancies,” he said. “Currently, 84 percent of the world's population resides in low- and middle-income countries where most of the population growth is occurring. The fastest growing region is sub-Saharan Africa whose population will double in the next few decades. Stroke is clearly the biggest threat to neurological health globally, responsible for 47 percent of the global burden of neurological disorders.”


Wolfgang Grisold, MD, Secretary General of the World Federation of Neurology (WFN), said that with this study, the authors were “courageous enough to reach over the prevalent corset of classification,” thereby “allowing a more expanded and timely view on the prevalence of neurological diseases.”

“The new study provides important evidence that brain diseases have moved on from an under-estimated, under-recognized, and under-resourced group of conditions to a major challenge for health policy worldwide and that sufficient resources have to be provided for disease prevention and management,” he said.


DR. VALERY FEIGIN: “The most surprising findings were the amount of increase in the burden from 1990 to 2015 in virtually all countries of the world and that neurological disorders are now the leading causes of disability among all groups of diseases.”


AGE-STANDARDIZED rates of disability-adjusted life years (DALYs) and (B) deaths per 100,000 people from all neurological disorders combined in 2015.

The WFN cooperates with a wide range of organizations at the global and regional level to address this challenge, he said.

“The important impact of neurological diseases on global health is increasingly being discussed in the framework of international organizations,” he said. The WHO Global NCD (non-communicable diseases) Action Plan 2013-2020 and the Sustainable Development Goals of the United Nations are two projects aimed at the prevention of neurological conditions.

But he added that the recent WHO-WFN Neurology Atlas publication “shows that the resources available for neurological diagnosis, therapy, and access to neurological care are still very unevenly distributed globally. These new data will give us additional arguments to make the point that sufficient resources for brain health have to be provided at all levels.”

WFN is also devoted to improving neurological care worldwide, he said, with a program to “ensure knowledge transfer across national borders,” with low-income countries as the main target.

“The disparity and inequalities of health systems, the lack of financial resources in many countries, cultural and religious hurdles, as well as political aspects are among the major obstacles to making more progress in the field of neurological care on the global scale.”

The World Stroke Organization (WSO) is leading awareness campaigns among the general population and among health professionals, said Bo Noorving, MD, PhD, past president of the WSO.

“We advise decision-makers and governmental bodies on best scientifically-based policies,” he said. “We arrange stroke congresses, and we have many education activities ongoing. The greatest barriers relate to shortage of resources in the health system, the underfunding of stroke services, and the difficulties to change established habits.”

He said that the organization will continue its strong advocacy for stroke resources and that stroke “is no longer invisible under the umbrella of ‘cardiovascular diseases,’ but identified on its own as one of the core NCDs, possible to prevent and treat.”

Dr. Chin, who is now teaching and providing pro bono neurological care in Uganda, where he spends two months a year, said the barriers to basic neurological care in sub-Saharan Africa and South Asia, where he has also worked, are “numerous and complex.”


RANKING OF AGE-STANDARDIZED DALY rates for all neurological disorders by Global Burden Disease region in 2015.

“The neurological workforce gap is a key element, in addition to a lack of universal health care coverage, limited health-sector budgets, and inadequate preventive care and health education,” he said.

For its part, the AAN, the membership of which 20 percent is international, offers reduced membership rates for members in low- and middle-income countries; offers an international scholarship award to attend the annual AAN meeting; provides education programs at its Annual Meeting; supports the annual European Academy of Neurology regional teaching course in Africa; and offers free copies of Continuum, a publication for lifelong learning, to eligible institutions through the WFN.

Dr. Chin said that the AAN Global Health Section, launched by him and four colleagues in 2011, has grown from 50 signatories to 400 members.

“As a result of the formation of the section, there are science and education topic categories in global health at the AAN Annual Meeting, which has stimulated increasing interest in global neurology.”


• GBD 2015 Neurological Disorders Collaborator Group. Global, regional, and national burden of neurological disorders during 1990-2015: A systematic analysis for the Global Burden of Disease Study 2015 Lancet Neurol 2017; Epub 2017 Sep 17.