Anorexia nervosa is widely cited as the deadliest mental illness, but the full picture is more complicated. A large meta-review covering over 1.7 million patients found that substance use disorders, particularly opioid, cocaine, and amphetamine use, actually carry higher mortality risks than anorexia in some analyses. The answer depends on how you measure “deadliest,” whether by raw death rates, years of life lost, or risk compared to the general population.
Why Anorexia Nervosa Tops Most Lists
Anorexia nervosa has a standardized mortality ratio of 4.37, meaning people with the condition are more than four times as likely to die at any given age compared to the general population. For young women between 15 and 24, the annual death rate among those with anorexia is more than 12 times higher than the death rate from all causes in that age group, and more than 200 times greater than the suicide rate in the general population.
The causes of death split roughly evenly between two categories. In one long-term study published in the American Journal of Psychiatry, out of 16 deaths among participants with eating disorders, four were from suicide (all in people with anorexia) and four were from cardiac causes like arrhythmia and cardiopulmonary arrest. Severe malnutrition weakens the heart muscle, disrupts electrolyte balance, and can trigger fatal heart rhythms. This combination of physical deterioration and high suicide risk is what makes anorexia so lethal relative to other psychiatric conditions.
Substance Use Disorders May Be Deadlier
The claim that anorexia is the single deadliest mental illness requires an asterisk. A 1998 systematic review comparing mortality across 27 mental disorders found that prescription drug abuse and opioid abuse had higher death rates than eating disorders in several analyses. A more recent meta-review from 2014 confirmed this pattern, estimating that opioid use, cocaine use, and amphetamine use all carry greater mortality risk than anorexia nervosa.
The reason anorexia often gets the top spot is partly a classification issue. Substance use disorders are sometimes categorized separately from “mental illnesses” in older research, even though modern diagnostic systems include them. When substance use disorders are included in the comparison, they and anorexia cluster together at the top of the mortality rankings, with both carrying risks comparable to or greater than heavy smoking.
Schizophrenia and the Life Expectancy Gap
If you measure deadliness by total years of life lost rather than the rate of death at a given moment, schizophrenia becomes a strong contender. People with schizophrenia lose an estimated 10 to 25 years of life expectancy compared to the general population. In Finland, where detailed population data allows precise tracking, schizophrenia lowers life expectancy by 15.5 years in men and 10.9 years in women.
Suicide plays a role here. Schizophrenia carries the highest adjusted odds of suicide mortality among all diagnosed mental health conditions, at 15 times the risk of the general population. Bipolar disorder follows closely at about 13 times the risk. But suicide is not the primary driver of early death in schizophrenia. The majority of excess deaths come from physical diseases, especially cardiovascular problems, metabolic conditions, and respiratory illness. People with schizophrenia face barriers to healthcare, higher rates of smoking, medication side effects that promote weight gain and diabetes, and social isolation that compounds every other risk factor.
Bipolar Disorder and Depression
Bipolar disorder carries one of the highest suicide risks of any mental illness and significantly shortens life expectancy through both direct and indirect pathways. The adjusted odds of dying by suicide are about 13 times higher than in the general population. Beyond suicide, people with bipolar disorder have elevated rates of heart disease, diabetes, and other chronic conditions that accumulate over decades.
Major depression, while lower on mortality rankings than schizophrenia or anorexia, affects far more people. Its contribution to premature death is enormous at a population level even if the individual risk is lower. Depression increases the likelihood of heart disease, weakens immune function, and is the most common diagnosis preceding suicide.
Why Physical Disease Drives Most Deaths
Across all severe mental illnesses, the leading causes of premature death are not what most people expect. While suicide draws the most attention, excess deaths in people with mental disorders are mainly attributed to physical diseases. Heart disease, stroke, diabetes, respiratory illness, and infections account for far more lost years than suicide does.
This happens through several overlapping mechanisms. Mental illness often leads to reduced physical activity, poor nutrition, heavy smoking, and alcohol use. Psychiatric medications can cause significant weight gain and metabolic changes. People with severe mental illness frequently receive less preventive healthcare and have symptoms diagnosed later. Social factors like poverty, homelessness, and isolation make all of these worse. The result is a mortality gap that persists even in countries with universal healthcare.
Treatment Makes a Measurable Difference
The deadliness of these conditions is not fixed. Treatment dramatically changes the odds. In schizophrenia, for example, one large study followed over 2,300 people with treatment-resistant illness and found that those not receiving appropriate medication had nearly twice the rate of death compared to those who were treated. Stopping treatment was particularly dangerous: in the year after discontinuing medication, the mortality rate jumped to 2.65 times higher than during treatment. Self-harm rates were also significantly lower during active treatment.
For anorexia nervosa, early intervention and sustained nutritional rehabilitation reduce mortality risk substantially, though the condition remains difficult to treat and relapse rates are high. The critical window matters: the longer someone remains severely underweight, the greater the cumulative damage to the heart, bones, and organs. For substance use disorders, medication-assisted treatment for opioid addiction has been shown to cut overdose deaths by half or more.
The pattern across all of these conditions is consistent. Sustained, appropriate treatment narrows the mortality gap. Gaps in care, treatment discontinuation, and lack of access to both psychiatric and medical services widen it.