The Centers for Disease Control (CDC) and Prevention says that at any given moment about a quarter of American adults are mentally ill and that over the course of their lifetimes about half of all Americans will develop at least one mental illness.
A CDC mental-health fact sheet–Mental Illness Surveillance Among U.S. Adults–says that “published studies report that about 25% of all U.S. adults have a mental illness and that nearly 50% of U.S. adults will develop at least one mental illness during their lifetime.”
The fact sheet also notes that the authors of a 2011 CDC mental health surveillance report pointed out that “currently, no surveillance efforts at the national or state level are directed toward documenting anxiety disorders.” The authors thus call for “initiating national-level anxiety disorder surveillance activities.”
Mental illness, says the CDC, “refers collectively to all diagnosable mental disorders” and that “the most common mental illnesses in adults are anxiety and mood disorders.” Mental illnesses effects “include sustained abnormal alterations in thinking, mood, or behavior associated with distress and impaired functioning.”
In addition, says the agency, “mental illness is associated with increased occurrence of chronic diseases such as cardiovascular disease, diabetes, obesity, asthma, epilepsy, and cancer.”
“The most common mental illnesses in adults are anxiety and mood disorders,” says the fact sheet.