Otherwise healthy people who experience hallucinations or delusions are more likely to have later suicidal thoughts or attempts, an international study has found.
The University of Queensland-led research found that having a psychotic experience doubled the risk of suicidal thoughts and behaviours.
UQ Queensland Brain Institute researcher Professor John McGrath said children were at even greater risk.
"The risk of suicidal thoughts was five or six times higher in children under 12 who had experienced psychosis," Professor McGrath said.
The research examined the links between psychotic experiences and suicide risk in the general population, and involved more than 33,000 people in 19 countries.
"Psychotic experiences appear to be a marker of general psychological distress," Professor McGrath said.
"Our previous research has found that hearing voices and seeing things that others can't is more common than expected, as about one in 20 people experience this at some point in their lives."
Queensland Brain Institute Director Professor Pankaj Sah said the research could have significant impact on public health guidelines for doctors screening for suicide risk.
"Suicide attempts are relatively rare outcomes, but because they are rare they are hard to predict," Professor Sah said.
Professor McGrath said questions about psychotic experiences in routine screening could improve prediction of subsequent suicide risk.
He said the higher risks for children under 12 underscored how the pattern of mental disorders changed throughout the lifetime.
Study participants were asked about psychotic experiences, mental disorders, as well as any suicidal thoughts, plans and attempts.
"We were able to adjust the data for a range of common mental disorders, such as depression," Professor McGrath said.
"Even in adjusting for these mental illnesses, people who'd had a psychotic experience still had a greater subsequent suicide risk."
The study was based on community samples, but excluded people diagnosed with schizophrenia or other psychotic disorders.
The research, published in JAMA Psychiatry, was funded by the National Health and Medical Research Council and the Danish National Research Foundation.