About 61.5 million American adults, or 23.4% of the adult population, had a mental illness in the past year. That figure comes from SAMHSA’s 2024 National Survey on Drug Use and Health, the largest annual survey tracking mental health across the country. Of those, 14.6 million (5.6%) had a serious mental illness, meaning a condition that substantially interfered with one or more major life activities.
What Counts as “Any Mental Illness”
The survey uses two categories. “Any mental illness” (AMI) covers the full spectrum, from mild anxiety that flares during stressful periods to chronic conditions like schizophrenia. “Serious mental illness” (SMI) is a narrower subset: conditions severe enough to seriously limit everyday functioning, such as holding a job, maintaining relationships, or managing basic self-care. The 61.5 million figure captures everyone across that range, so it includes millions of people whose symptoms are manageable alongside millions who are significantly disabled by their condition.
Who Is Most Affected
Mental illness is not evenly distributed across age groups. Young adults ages 18 to 25 have the highest rate at 36.2%, more than double the rate for adults over 50 (13.9%). Adults 26 to 49 fall in between at 29.4%. The pattern holds for serious mental illness too: 11.4% of young adults qualify, compared to just 2.5% of those 50 and older.
Women are diagnosed at higher rates than men. About 26.4% of women had any mental illness in the past year, compared to 19.7% of men. For serious mental illness specifically, 7.0% of women versus 4.0% of men.
Rates also vary by race and ethnicity. People identifying as two or more races report the highest rate of any mental illness at 35.2%, followed by white adults at 24.6%. Asian Americans report the lowest rate at 16.8%. For serious mental illness, American Indian and Alaska Native adults have the highest rate at 9.3%.
Children and Teenagers
The numbers above only count adults. Nearly 1 in 5 children ages 3 to 17, about 21%, have been diagnosed with a mental, emotional, or behavioral health condition. Anxiety is the most common, affecting 11% of children in that age range. Behavior disorders affect 8%, and depression affects 4%. Girls are more likely to be diagnosed with anxiety and depression, while boys are more likely to be diagnosed with behavior disorders.
Among adolescents, the picture is more striking. In 2023, the CDC found that 40% of high school students reported persistent feelings of sadness or hopelessness, and 20% had seriously considered attempting suicide. One in five adolescents ages 12 to 17 reported symptoms of anxiety in the prior two weeks, and roughly the same proportion reported symptoms of depression.
Mental Illness and Substance Use Often Overlap
A significant portion of people with mental illness also struggle with substance use. Approximately 21.2 million American adults have both a mental illness and a substance use disorder at the same time. That overlap complicates treatment, since addressing one condition without the other tends to produce worse outcomes. These “co-occurring disorders” are common enough that most treatment programs now screen for both.
The Treatment Gap
Having a diagnosable condition and getting help for it are two very different things. Research on global treatment gaps found that more than half of people with major depression (56.3%), generalized anxiety disorder (57.5%), and bipolar disorder (50.2%) go untreated. Alcohol use disorders have the widest gap: 78.1% of people who meet diagnostic criteria never receive care.
Part of the problem is access. Nearly 149 million Americans live in areas formally designated as mental health professional shortage areas, meaning there simply aren’t enough providers to meet demand. Closing that gap would require adding roughly 7,400 practitioners nationwide. Rural communities, low-income urban neighborhoods, and tribal lands are hit hardest.
The Economic Cost
Mental illness costs the U.S. economy an estimated $282 billion per year, equivalent to about 1.7% of GDP. Research from Columbia Business School put that figure in perspective: it’s roughly equal to the economic damage of an average recession. Those costs come from lost earnings, reduced productivity, increased healthcare spending, and disability. The burden falls on individuals, families, employers, and public systems simultaneously.
Mental Health and Suicide
Mental illness is commonly assumed to be the primary driver of suicide, but the relationship is more complicated than most people realize. A study examining over 70,000 male suicide deaths between 2016 and 2018 found that 60% of victims had no documented mental health condition. Men account for 80% of all suicide deaths in the U.S., and for the majority of them, factors like relationship problems, financial stress, legal troubles, and chronic pain appear to play a larger role than a diagnosed mental illness. This doesn’t mean mental health is irrelevant to suicide prevention, but it does mean that screening for diagnosable conditions alone misses most of the people at risk.