One out of every five adults who attempt suicide never met the criteria for a mental illness by the time the attempt happened, new research shows.

“This finding challenges clinical notions of who is at risk for suicidal behavior and raises questions about the safety of limiting suicide risk screening to psychiatric populations,” concluded a team led by Dr. Maria Oquendo. She's past president of the American Psychiatric Association and a professor of psychiatry at the University of Pennsylvania.

The study, published Feb. 21 in the journal JAMA Psychiatry, focused on data from nearly 2,000 Americans ages 20 to 65 who had all had a history of suicide attempt.

The study found that 6.2% had no history of a mental illness prior to or after their attempted suicide.

Another 13.4% had made a first attempt at suicide prior to the onset of any mental illness diagnosis. Some did not meet the criteria for a mental illness until years after the attempt, the study found.

That means that a total of 19.6% of adults with a lifetime history of attempted suicide had no prior evidence of mental illness beforehand.

For doctors, this means that they may need to be ask patients questions regarding any prior attempt at suicide, because it may have happened in the absence of a diagnosed mental illness.

According to the researchers, a prior attempted suicide is a big risk factor for future attempts.

Making inquiries about suicide common practice "beyond the current targets" could end up saving lives and health care dollars, the researchers said.

If you or a loved one is having suicidal thoughts, the 988 Suicide and Crisis Lifeline offers free, anonymous 24/7 help.