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People who hear voices but are not diagnosed with a psychotic illness could boost the knowledge of psychiatrists. Istock

To understand why people who suffer from psychosis sometime hear voices, scientists at the University of Yale have worked with "psychics" to find out why such voices appeared. This unconventional approach was tried out because very little progress has been made in recent years to treat psychosis.

Psychosis is a mental health problem which causes people to perceive things in a different way than those around them. Hallucinations and delusions are common features – very often patients have "auditory hallucinations". They are tormented by voices that only they can hear.

The condition is more common that people realise, with roughly 1 new case for 2,000 people diagnosed each year in England. Schizophrenia is the most common psychiatric disease associated with psychosis.

Other research has shown that as many as one in 25 people hear voices at any given time and up to 40% may report hearing a voice at some time in their lives. However, the great majority are not diagnosed with a mental illness. Scientists believe they can learn a lot from these people and their voices, to improve treatment for patients with a diagnosis of psychosis.

"We have known for some time that people in the general population can have the experience of hearing voices — sometimes frequently — without the need for psychiatric intervention," explains Albert Powers, the lead author of the study.

The problem is that recruiting healthy people who have heard voices at some point in their lives has proven complicated. This is why in the study, due to be published in Schizophrenia Bulletin, the researchers have sought the help of "psychics" – people who had no problem saying they heard voices and have no diagnosis of psychotic disease.

Clairaudient psychics

The team worked with a group of participants known as "clairaudient psychics", who report receiving daily messages from voices. They recruited 17 psychics, 16 schizophrenic patients who heard voices, 16 schizophrenic patients who didn't hear voices and a control group of 18 people who neither had a diagnosis nor heard voices.

The participants were given tests from forensic psychiatry to identify those who made false claims about hearing voices. They were also asked about their experiences hearing voices.

Patients diagnosed with a psychotic illness were much more likely to report negative experiences when hearing voices or discussing the voices with other people. In contrast, "psychics" were much more likely to perceive the voices as positive or helpful and appeared to have more control over them. Another notable difference was the fact people with schizophrenia reported having first heard voices later in life than psychics – around the age of 19 vs around the age of six.

The scientists believe taking such an original approach – studying psychosis through the lens of voice-hearing – will allow them to understand why healthy patients who hear voices are able to function so well without the need for psychiatric care, and how they could serve as model for coming up with future treatments.

"These individuals have a much higher degree of control over the voices. They also have a greater willingness to engage with and view the voices as positive or neutral to their lives,'' senior author Philip Corlett concludes. "We predict this population will teach us a lot about the neurobiology, cognitive psychology and eventually treatment of distressing voices."