However, many people not suffering from diagnosable mental illness may sometimes hear voices as well.
Most individuals with a diagnosable mental illness pose no risk to society.
Roughly a quarter of all adults 18 and over in the US suffer from a diagnosable mental illness.
Researchers report that more than 90 percent of suicide fatalities had depression or "another diagnosable mental illness or substance abuse disorder."
An estimated 26.2 percent of Americans ages 18 and older - about one in four adults - suffer from a diagnosable mental illness in any given year.
Engagement in life itself, he suggested drily, has become a diagnosable mental illness.
However, the exact nature of the relationship between schizotypy and diagnosable psychotic illness is still controversial.
The study also found that people with diagnosable mental illness were about twice as likely to smoke as other people.
Preliminary reports say most of those examined have ordinary, diagnosable illnesses, while a small portion have symptoms that are unexplained.
However, individuals may hear voices without suffering from diagnosable mental illness.