Neurologic diseases and disorders are now the leading cause of disability nationwide, affecting half the US population.

A systematic analysis showed that 1 in 2 people, ie, nearly half the US population, is affected by a neurologic disease or disorder.

Headache disorders are by far the most prevalent, while stroke, dementia, diabetic neuropathy, and migraine account for the greatest disability.

The findings are “an urgent call to action,” Natalia Rost, MD, MPH, president of the American Academy of Neurology, said in a news release.

“It emphasizes the importance of accelerating research and discovery to achieve scientific breakthroughs in preventing and treating neurologic diseases and disorders. With these efforts, led by neurologists and neuroscientists, the experts in brain health, we can improve brain health for all,” she added.

The study was published online on November 24 in JAMA Neurology.

A Comprehensive Analysis

Nervous system disorders span the entire lifespan, from neonatal and congenital conditions to neurodevelopmental disorders, migraine, epilepsy, stroke, dementia, and the neurologic effects of systemic illnesses such as diabetes.

Global data suggest that about one third of people worldwide live with a disorder affecting nervous system function. However, prevalence in the US is nearly 10% higher than that in other countries.

Until now most national assessments have primarily focused on age-related neurologic diseases and have largely overlooked the contribution of congenital, neonatal, neurodevelopmental, and systemic conditions from birth to older age, the investigators noted.

To address this research gap and understand the true national impact of neurologic diseases, the authors used Global Burden of Disease 2021 data to aggregate 36 conditions and quantify the prevalence, disability, mortality, and years lived with disability (YLDs) attributable to neurologic disorders.

They estimated the number of disability-adjusted life-years (DALY), a measure used to assess disease burden, by summing YLDs and YLLs for each condition, age, sex, location, and year.

Results showed that in 2021, 54.2% of individuals in the US, or 180.3 million individuals were affected by at least one neurologic disorder or disease. The most prevalent conditions were tension-type headache at 121.9 million people affected, migraine at 57.7 million and diabetic neuropathy at 17.1 million. Stroke was the leading cause of net health loss at 3.9 million DALYs. 

Sharp Increase in Disease Burden

From 1990 to 2021, there was a sharp rise in the US neurologic disease burden. The prevalence of neurologic disorders increased by 34.4% (95% uncertainty interval [UI], 31.7%-37.4%), and DALYs climbed by 55.2% (95% UI, 48.3%-62.5%) — a far greater increase than seen globally. 

During the same period, deaths from these conditions rose by 64.2% (95% UI, 55.1%-72.8%), while both YLDs and YLLs increased by 67.5%.

“However, when accounting for the effects of an aging population, the increase was much smaller. This pattern shows that much of the rise in neurologic disease burden is linked to an older US population that is more vulnerable to conditions affecting the nervous system,” study investigator John Ney, MD, MPH, of Yale University in New Haven, Connecticut, said in the release.

Deaths over the same period decreased by 14.6% after accounting for age changes in the population. States in the “Stroke Belt” — notably Mississippi, Alabama, and Louisiana — experienced the highest levels of health loss.

In addition to stroke, the analysis showed that Alzheimer’s disease and other dementias were major drivers of health loss, accounting for 3.3 million DALYs. These conditions were followed by diabetic neuropathy and migraine, which contributed to 2.2 million and 2.1 million DALYs, respectively.

Overall age-standardized prevalence of nervous system disorders remained essentially unchanged since 1990, but YLDs increased by nearly 10%, reflecting a shift toward chronic, disabling conditions rather than mortality.

The researchers also found notable sex differences, with migraine and multiple sclerosis more common in women, while Parkinson’s disease, attention-deficit/hyperactivity disorder, and autism spectrum disorder were more common in men.

Study limitations included the omission of some neurologic disorders from the health-loss analysis and the exclusion of deaths for certain conditions. The authors urged increased investment in research, more clinical trials for effective therapies, and better access to neurologists and disability care.

This work was supported by the Gates Foundation (OPP 1152504). See study for full list of author disclosures.