Anorexia nervosa has long been cited as the mental illness with the highest mortality rate, with death rates more than 12 times higher than expected for the general population of the same age and sex. But the full picture is more nuanced: when substance use disorders are included in the comparison, opioid, cocaine, and amphetamine use disorders all carry higher mortality risks than anorexia. The answer depends on whether you count substance use disorders as mental illnesses, which modern diagnostic manuals do.
How Mortality Rates Are Measured
Researchers don’t simply count deaths. They use something called a standardized mortality ratio, which compares how many people with a given condition die versus how many deaths you’d expect in a matched group of people without that condition. A ratio of 2.0 means twice the expected death rate. A ratio of 12 means twelve times the expected rate. This method accounts for differences in age and sex, making it possible to compare conditions that affect very different populations.
By this measure, the conditions with the highest all-cause mortality ratios are substance use disorders and anorexia nervosa. Among psychiatric conditions that don’t involve substance use, anorexia stands alone at the top.
Anorexia Nervosa: The Deadliest Non-Substance Disorder
The aggregate annual mortality rate for anorexia nervosa is more than 12 times higher than the annual death rate from all causes for females aged 15 to 24 in the general population. It is more than 200 times greater than the suicide rate in the general population. These numbers make anorexia extraordinarily lethal relative to who it affects: mostly young people who would otherwise have decades of life ahead.
Death from anorexia happens through several pathways. Severe caloric restriction disrupts the balance of essential minerals in the blood, particularly potassium and sodium, which can trigger fatal heart rhythms. The heart muscle itself can weaken and shrink. Organ failure, particularly of the kidneys and liver, becomes a risk as the body breaks down its own tissue for energy. Research from Yale has identified a specific biological mechanism: neurons that help the body access energy from fat stores stop functioning properly during prolonged starvation combined with excessive exercise. When those neurons are suppressed, the body loses its ability to mobilize backup fuel sources, which can be fatal within days.
Suicide also accounts for a significant share of anorexia deaths. The psychological toll of the illness, often compounded by depression and anxiety, makes self-harm a persistent risk throughout the course of the disease.
Substance Use Disorders Carry Even Higher Risk
When substance use disorders are classified alongside other mental illnesses, as they are in the DSM-5, opioid use disorder surpasses anorexia in raw mortality. In 2023, over 105,000 people in the United States died from drug-involved overdoses. Opioid-involved overdose deaths alone reached 79,358 that year, down slightly from a peak of 81,806 in 2022 but still dramatically higher than the 49,860 recorded in 2019.
Cocaine and amphetamine use disorders also carry mortality ratios that exceed anorexia’s. The risk is concentrated in acute events like overdose, but chronic use also damages the cardiovascular system and other organs over time. The sheer scale of opioid deaths in the U.S. has made substance use disorder the leading killer among all psychiatric conditions by both relative risk and absolute numbers.
Schizophrenia and Bipolar Disorder
Schizophrenia and bipolar disorder don’t match anorexia or substance use disorders in mortality ratios, but they still dramatically shorten lives. People with schizophrenia die at roughly 2.9 times the rate of the general population. For bipolar disorder, the figure is about 2.5 times the expected rate. Broader categories of psychotic disorders show even larger increases.
What makes these conditions especially devastating is not a single catastrophic event but a slow accumulation of physical health problems. Cardiovascular disease is the leading cause of excess death in schizophrenia, not suicide, as many people assume. People with schizophrenia have significantly higher rates of heart disease and type 2 diabetes, driven by a combination of medication side effects, reduced access to healthcare, higher smoking rates, and metabolic changes linked to the illness itself. The result is a life expectancy gap estimated at 15 to 20 years shorter than the general population.
Bipolar disorder follows a similar pattern. While suicide risk is elevated, particularly during depressive episodes, cardiovascular disease and metabolic conditions account for the majority of early deaths.
Why the Rankings Shift Depending on the Source
You’ll find different answers to this question depending on where you look, and the reason comes down to classification. Many sources that call anorexia “the deadliest mental illness” are excluding substance use disorders from the comparison. This isn’t wrong, exactly. For decades, addiction and psychiatric illness were treated as separate categories. But current diagnostic frameworks group them together, and when you do that, substance use disorders clearly rank higher.
Study design also matters. Mortality ratios can vary based on whether researchers tracked inpatients, outpatients, or community populations. Follow-up length, the country studied, and the age and sex of participants all introduce variation. A study following hospitalized anorexia patients will show higher mortality than one tracking people diagnosed in outpatient clinics, because the hospitalized group is sicker to begin with.
The most reliable comparisons come from large meta-analyses that adjust for these differences. Across those studies, the ranking is consistent: substance use disorders first, anorexia nervosa second, then schizophrenia and other psychotic disorders, followed by bipolar disorder and major depression.
What These Numbers Mean in Practice
Mortality statistics describe populations, not individuals. A 12-fold increase in death rate sounds terrifying, and it should be taken seriously, but it reflects the average across all people diagnosed with a condition at varying levels of severity. Many people with anorexia recover fully. Many people with substance use disorders achieve long-term sobriety. The elevated risk is real, but it is not a fixed outcome.
What these numbers do reveal is where the healthcare system fails most dramatically. The conditions with the highest mortality rates are also among the most undertreated. Fewer than one in four people with an eating disorder receive treatment. Access to evidence-based addiction care remains limited in much of the country. And people with schizophrenia routinely receive inadequate screening for the cardiovascular conditions most likely to kill them. The mortality gap in mental illness is not just a medical problem. It reflects how seriously these conditions are taken and how aggressively they are treated.