Hallucinations and delusions are more common than we thought

Salvador Dali. Portrait of Pablo Picasso in the Twenty-first Century, 1947. Quim Llenas/Cover/Getty Images

Hallucinations and delusions are more common than previously thought, according to study led by The University of Queensland and Harvard Medical School.

The research found that hearing voices and seeing things others cannot impacts about 5% of the general population at some point in their lives.

John McGrath, a Queensland Brain Institute professor, says the study of more than 31,000 people from 19 countries is the most comprehensive completed.

“We used to think that only people with psychosis heard voices or had delusions, but now we know that otherwise healthy, high-functioning people also report these experiences,” McGrath says.

“Of those who have these experiences, a third only have them once and another third only have two-to-five episodes across their life. These people seem to function reasonably well.

“So it’s incredibly interesting that not only is hearing voices more common than previously thought, but it’s not always linked to serious mental illness.”

The study found that auditory hallucinations are more common in women than men and they are also more common in people from wealthier countries.

Professor McGrath says the findings could help generate new research into the causes of the symptoms.

“In particular, we are interested in learning why some people recover, while others may progress to more serious disorders such as schizophrenia,” he says.

“We need to understand why it’s temporary for some people and permanent for others. We can use these findings to start identifying whether the mechanisms causing these hallucinations are the same or different in both situations.”

The study is published in the journal JAMA Psychiatry.

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