Healthy people who have occasional hallucinations or delusions are more likely to experience mood and anxiety disorders, University of Queensland researchers have found.

The Queensland Brain Institute’s Professor John McGrath has previously determined that five per cent of the general population occasionally experience hallucinations– sights or sounds that no one else can hear – and about one per cent of the general population also have delusional, or false, beliefs.

Now Professor McGrath’s team have discovered new links between hallucinations, delusions and the risk of having a common mental disorder like anxiety or depression.

The team completed analysis of 31,000 people from more than 19 countries to get the results.

“Once it had emerged that hallucinations were much more common than we thought – one in 20 healthy people will experience them – we wanted to see if they were a warning sign of what might be to come,” Professor McGrath said.

“It became clear that not only were you more at risk of psychotic disorders, like schizophrenia, but also those very common disorders – anxiety, depression, eating disorders.

“But in a fascinating flip, we also found that hallucinations were more likely to first happen after a person develops one of those common disorders.

“This means we, as clinicians, need to rethink our approach to hallucinations and delusions.

“It’s becoming clear they have a much more subtle, yet more complex involvement in mental health issues than we’d recognised.

“Certainly, doctors need to keep an open mind, and to factor in these questions when we talk with people with any mental disorders.

“And as researchers we will continue to drill further into the range of risk factors that come into play.”

The research, drawing on the World Health Organisation World Mental Health surveys is published in The American Journal of Psychiatry.

Professor McGrath is funded by the John Cade Fellowship.

Watch a video of Professor McGrath explaining his work here.

Media: QBI Executive Communications Manager  Kirsten MacGregor, [email protected], 0448 108 441.

This article first appeared on ‘UQ News’ on 21 March 2016.