A Lancet study has published updated figures on the global prevalence and burden of mental disorders, having systematically analyzed data from 1990 through to 2023. The study looked at 375 diseases and injuries, 12 of which are classed as mental disorders. The study covered 21 regions, and 204 countries and territories. The authors noted the ongoing issue with a wide treatment gap, i.e. the discrepancy between those who have an illness or disorder, and those who receive adequate care for it.
The 12 psychological disorders covered were anxiety disorders, major depressive disorder (MDD), dysthymia, bipolar disorder, schizophrenia, autism spectrum disorders (ASDs), conduct disorder, attention-deficit hyperactivity disorder, anorexia nervosa, bulimia nervosa, idiopathic developmental intellectual disability, and a residual category of other mental disorders.
The authors of the study used the data garnered to estimate years lived with disability (YLDs), a metric used to quantify the degree of non-fatal health cost that arises from the disorder, as well as disability-adjusted life-years (DALYs), which are used to quantify disease burden by quantifying the number of years of full health lost due to the disease.
The study reported that 1.17 billion people had a mental disorder globally in 2023 (95% CI 1.06-1.31 billion), or 14,210.7 cases per 100,000 people. Further, this represented an increase of 95.5% from 1990, with all mental disorders showing increases in this period. Increases were particularly high in anxiety disorders, MDD, dysthymia, anorexia nervosa, bulimia nervosa, schizophrenia, and conduct disorder.
6.1% of all DALYs in 2023 were attributed to mental disorders, making psychological illness the fifth leading cause of years of full health lost to disability or illness. In 1990, mental disorders were the 12th leading cause of DALYs. When looking only at non-communicable diseases, mental disorders were the third leading cause of DALYs, after cardiovascular diseases and neoplasms (i.e. tumors). All countries reported increases in mental disorders between 1990 and 2023.
Within mental disorders, anxiety was the leading cause of DALYs globally (ranked 5th overall), followed by MDD (15th), and schizophrenia (41st). Among the young (15-19), anxiety was the biggest cause of DALYs, followed by MDD, conduct disorder, and ASDs, respectively. These impacts were greater in females than in males among the young, driven by higher rates of anxiety disorders and MDD in females. In males, conduct disorder and ASDs were more prevalent.
The authors of the study write that one of the reasons behind the increase in mental disorders is declining mortality rates from communicable, maternal, nutritional, and neonatal diseases that allow people to live longer. Ongoing issues with large treatment gaps are also noted. They cite a previous study that reported that only 9.1% of individuals with MDD received “medically adequate treatment” in 2021 – with this treatment defined as either one month of medication and four visits to a medical doctor, or eight sessions of psychotherapy. This study reported that 10.2% of females with MDD had received treatment for it in 2021, and 7.2% of males. Globally, only seven countries had reached a treatment rate for MDD of 30% (Australia, Belgium, Canada, Germany, the Netherlands, South Korea, and Sweden), while 90 countries were sitting at lower than 5%. Sub-Saharan Africa was at 2%, meaning the treatment gap for MDD was 98%; of every 100 people with major depression in Sub-Saharan Africa in 2021, two received medically adequate treatment.
The authors of the study suggest the need for stronger surveillance of mental health, particularly in low-income and middle-income countries, as one way to begin addressing this situation. They also note the importance of inclusive policies that especially work on early treatment and prevention, with tailoring to sex and age differences across the globe.
The findings of the report are sobering and highlight the ongoing need for more research and access to evidence-based care – particularly in socioeconomically deprived parts of the world. The findings also highlight the need for systemic change in how we respond to mental health, and in the policies that are enacted to maintain well-being and prevent mental illness.