Global prevalence and disability burden of brain disorders: Impact of neurological, mental, and substance use disorders.

Brain disorders-encompassing neurological, mental, and substance use disorders-account for 10 of the top 25 causes of disability worldwide according to the Global Burden of Disease (GBD) 2021 study. Despite such an impact, they have not been centrally analyzed in prior GBD studies. This paper synthesizes the latest disability-focused GBD study to quantify the prevalence and disability burden of 35 conditions from 2010 to 2021, a period marking the first decline in global health outcomes in three decades. It further incorporates disability metrics from 2021 to 2023 to contextualize post-pandemic trends. The paper covers the prevalence and disability burden of neurological, mental, and substance use disorders along with COVID-19 using disability-adjusted life-years (DALYs) and years lived with disability (YLDs) metrics. From 2010-2021, Parkinson's, Alzheimer's, and migraine (in neurological disorders), major depressive, anxiety, and eating disorders (in mental disorders), and opioid and drug use disorders (in substance use disorders) showed the greatest increases in age-adjusted prevalence rates across both sexes. In 2021, neurological disorders were the largest contributor to DALYs among brain-disorder categories, while depressive and anxiety disorders ranked as the 2nd and 6th leading causes of global YLDs. Alzheimer's disease/dementias, Parkinson's disease, autism spectrum disorder (ASD), depressive and anxiety disorders, and opioid and drug use disorders showed the largest increases in burden within their respective categories between 2010 and 2021. In both 2021 and 2023, females had higher prevalence rates of overall neurological disorders, headache/migraine, multiple sclerosis, depressive/anxiety disorders, and anorexia nervosa, while males had higher rates of stroke, Parkinson's disease, ASD/ADHD, and substance use disorders. In DALY/YLD metrics, females showed higher rates for anorexia nervosa and multiple sclerosis, and males for ASD, certain neurological disorders, COVID-19, and substance use disorders. In the 2021-2023 extension analysis, disability data showed increases in prevalence and disability of several brain disorders, mostly anxiety disorders, while the COVID-19 disability burden declined markedly by 2023. Further sex-specific disability burden metrics, key insights from each disorder, and limitations/confounds are discussed.