A new study published in the journal BMC Psychiatry looked at the prevalence of the mental illnesses, which include depression, bipolar disorder, schizophrenia, and PTSD.
The study found that there were approximately 1.6 million people with mental illnesses in the US.
The researchers found that nearly a third of people in the study were diagnosed with depression.
The most common mental illnesses were schizophrenia and PTSD, the researchers found.
They also found that more than half of the people with depression had a history of bipolar disorder.
The report also found some similarities between mental illnesses and other health issues, such as substance abuse and suicidal thoughts.
The prevalence of mental illness was highest in areas of the country with higher rates of mental health services, such the Northeast, Midwest, and South.
The authors said the study could help inform the development of better mental health care, as well as how to improve the care for those with mental illness.
“Our research highlights that mental health disorders are a complex constellation of complex causes and conditions, which may not be well understood by the general public and which often require ongoing and appropriate care,” said the report’s author, Dr. Susan A. Sorenson, a professor of psychiatry at Northwestern University.
Mental illness is a common and chronic health problem that affects an estimated 13 million Americans.
Mental health professionals have been concerned about the high rates of suicide and other mental illnesses among adults with mental health problems, especially in the U.S.
A 2013 study found nearly 50% of Americans over age 65 have a mental illness in some form.
In the report, the authors say there is a need to better understand how mental illness affects people of all ages and race groups, and how it is managed.
Sorenson and her colleagues are continuing to conduct their research, and hope to continue to identify new ways to help people who are struggling with mental disorders.