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New study finds at least twice as many US adults experience schizophrenia spectrum disorders than previously thought

Research provides up-to-date national estimates of specific mental health disorders for the first time in nearly 20 years

RESEARCH TRIANGLE PARK, N.C. — Researchers at RTI International, a nonprofit research institute, have found that approximately 3.7 million, or 1.8%, of adults in the U.S. ages 18 to 65 have a lifetime history of schizophrenia spectrum disorders — a figure two-to-three times higher than previous studies. Schizophrenia spectrum disorders include schizophrenia, schizoaffective disorder and schizophreniform disorder.

Through the Substance Abuse and Mental Health Services Administration (SAMHSA)-funded Mental and Substance Use Disorder Prevalence Study (MDPS), RTI led a national study in collaboration with Columbia University, the New York State Psychiatric Institute, Duke University, Harvard University, the University of Washington, the University of Chicago and the Treatment Advocacy Center to provide up-to-date national estimates of mental health and substance use disorders among U.S. adults.

“The MDPS finding that schizophrenia spectrum disorders may be more prevalent than previously thought is especially important,” said Heather Ringeisen, Ph.D., vice president, health of populations at RTI and principal investigator of the project. “People with a schizophrenia spectrum disorder experience high levels of disability that present significant challenges in all aspects of their life.”

The research team used a population-based version of the Structured Clinical Interview of the Fifth Edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; SCID-5®) for mental health and substance use disorder diagnostic assessment. The MDPS included a nationally representative sample of households and prisons — as well as local samples of homeless shelters and state psychiatric hospitals — to provide more comprehensive estimates.

According to the study findings, one in four U.S. adults had at least one mental health disorder in the past year, with major depressive disorder and generalized anxiety disorder being the most common. Approximately 11% of adults ages 18 to 65 met the criteria for at least one substance use disorder; alcohol use disorder and cannabis use disorder were the most prevalent. In addition, the MDPS estimated that 11 million U.S. adults had both a mental health and substance use disorder in the past year.

The findings suggest that more individuals are seeking and accessing treatment compared to previous studies, with 61% of U.S. adults with a mental health disorder reporting at least one visit with a treatment provider in the past year. However, considerable treatment gaps still exist for the most common mental health disorders, the research team found. Within the past year, more than 40% of adults with major depressive disorder and more than 30% of those with generalized anxiety disorder did not receive any treatment services.

Past research suggests the life expectancy of individuals diagnosed with a schizophrenia spectrum disorder is 15 to 20 years shorter than adults in the general population. Treatments for schizophrenia spectrum disorders exist but not all people who are diagnosed receive effective treatment.  

“There are high levels of unmet treatment needs among individuals with schizophrenia spectrum disorders that may be due to stigma or the vulnerability of these individuals,” said co-principal investigator and RTI senior research scientist Mark Edlund, M.D., Ph.D. “The MDPS results highlight the need to improve systems of care and access to treatment for people with schizophrenia and other mental health disorders.”

Results from the MDPS provide updated data on the prevalence of mental health and substance use disorders to federal health agencies, researchers, clinicians and the public. The data promotes better understanding of the factors associated with mental health and substance use disorders and patterns of comorbidity to help improve prevention and treatment strategies.

The MDPS dataset will be available to researchers and policymakers in the fall of 2023 via the Institute for Social Research at the University of Michigan.

Read the full MDPS findings report

Learn more about RTI’s behavioral health research