Global Burden of Disease study examines prevalence of neurological disorders in US
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Noncommunicable neurological disorders resulted in “a large and increasing burden” in the United States, according to a systematic analysis of the Global Burden of Disease study from 2017 that was published in JAMA Neurology.
The three most burdensome neurological disorders in the United States, in terms of disability-adjusted life-years (DALYs), during this period included stroke, Alzheimer’s disease and other dementias, and migraine.
“Previous Global Burden of Diseases, Injuries and Risk Factors (GBD) Study articles have reported burden of diseases, injuries and risk factors among U.S. states and global, regional and country-specific estimates of the burden from neurological disorders, but no estimates for a comprehensive list of neurological disorders have been reported for the U.S. states from this study,” the researchers wrote. “This study provides estimates for noncommunicable and communicable neurological disorders at the state level from 1990 to 2017.”
Valery L. Feigin, MD, MSc, PhD, FAAN, director of and professor at the National Institute for Stroke and Applied Neurosciences at the University of Auckland and affiliate professor of global health at the Institute for Health Metrics and Evaluation at the University of Washington, and fellow GBD 2017 U.S. Neurological Disorders collaborators collected data on the incidence, prevalence, mortality and DALYs for major neurological disorders from the GBD 2017 U.S. study. The researchers examined 14 major neurological disorders, including stroke, AD and other dementias, Parkinson’s disease, epilepsy, MS, motor neuron disease, migraine, tension-type headache, traumatic brain injury, spinal cord injuries, brain and other nervous system cancers, meningitis, encephalitis and tetanus.
Researchers found that the burden of almost all neurological disorders, in regard to absolute number of incident, prevalent and fatal cases as well as DALYs, increased between 1990 and 2017, due in large part to the aging population. The five most prevalent disorders included tension-type headache (121.6 million people), migraine (68.5 million people), stroke (7.8 million people), AD and other dementias (2.9 million people), and spinal cord injuries (2.2 million people). The most burdensome in regard to DALYs included stroke (3.6 million DALYs), AD and other dementias (2.6 million DALYs), migraine (2.4 million DALYs), idiopathic epilepsy (0.4 million people) and Parkinson’s disease (0.4 million people).
The five leading causes of death from neurological disorders were from AD and other dementias (258,600 deaths), stroke (172,000 deaths), Parkinson’s disease (30,000 deaths), motor neuron disease (8,400 deaths) and MS (4,000 deaths). The highest incidence was of new-onset tension-type headache (44.5 million cases per year), followed by migraine (5 million cases per year), traumatic brain injury (0.96 million cases per year), stroke (0.60 million cases per year) and AD and other dementias (0.48 million cases per year).
Exceptions to these trends of increasing incidence included the rate of traumatic brain injury (29.1%), the rate of spinal cord injury (38.5%); meningitis prevalence (44.8%), deaths (64.4%) and DALYs (66.9%), and encephalitis DALYs (25.8%).
Feigin and colleagues also observed differences in the metrics for age-standardized rates of disease between states, from a 1.2-fold difference for tension-type headache to a 7.5-fold difference for tetanus. Southeastern states and Arkansas recorded a comparatively greater stroke burden, while northern states recorded a relatively higher burden of MS. Eastern states reported higher rates of Parkinson’s disease, idiopathic epilepsy, migraine and tension-type headache, as well as meningitis, encephalitis and tetanus.
“Falling rates of stroke, AD and other dementias, [traumatic brain injury], [spinal cord injury], meningitis and encephalitis might suggest that primary prevention of these disorders are beginning to show an influence, while between-state variations may be associated with differences in the case ascertainment, as well as access to health care; racial/ethnic, genetic and socioeconomic diversity; quality and comprehensiveness of preventive strategies; and risk factor distribution,” the researchers wrote. “For dementia, improving educational levels of cohort reaching the age groups at greatest risk of disease may also be contributing to a modest decline over time.”
The most burdensome disorders as measured by DALYs — stroke, AD and other dementias and migraine — matched findings from other high-income countries in 2016. The correlation between older age and certain disorders found to be prevalent in the U.S., including AD, stroke, Parkinson’s disease and motor neuron disease, “can be explained by the longer life expectancy in the U.S. compared with the world overall,” Feigin and colleagues wrote, and by better case ascertainment in the U.S., such as improved diagnosis, surveillance or reporting and health care access.
“The information reported in this article can be used by health care professionals and policy makers at the national and state levels to advance their health care planning and resource allocation to prevent and reduce the burden of neurological disorders,” Feigin and colleagues wrote.