Auditory hallucinations (hearing voices) can affect up to one-in-five children between the ages of 11 and 13, according to new research published online today by the British Journal of Psychiatry.

For most of these children, the auditory hallucinations stop as they get older – but those who continue to experience them may be at risk of complex mental illnesses.

The HRB-funded research team, led by Professor Mary Cannon, HRB Clinician Scientist at RCSI and Beaumont Hospital, assessed nearly 2,500 children, aged between 11 and 16 years, in four separate studies.

They found that 21-23% of younger adolescents (aged 11-13 years) had experienced auditory hallucinations. Just over half (57%) of the younger adolescents who heard voices were found to have a psychiatric disorder following clinical assessment.

In older adolescents (aged 13-16 years), just 7% reported hearing voices. However, nearly 80% of the older adolescents who heard voices were found to have a psychiatric disorder, showing a clear association between auditory hallucinations and serious mental illness.

Lead researcher on the paper Dr Ian Kelleher, RCSI explains: "We found that auditory hallucinations were common even in children as young as 11 years old. Auditory hallucinations can vary from hearing an isolated sentence now and then, to hearing 'conversations' between two or more people lasting for a several minutes. It may present like screaming or shouting and other times it could sound like whispers or murmurs. It varies greatly from child to child, and frequency can be once a month to once every day.

"For many children, these experiences appear to represent a 'blip' on the radar that does not turn out to signify any underlying or undiagnosed problem. However, for the other children, these symptoms turned out to be a warning sign of serious underlying psychiatric illness, including clinical depression and behavioural disorders, like attention deficit hyperactivity disorder. Some older children with auditory hallucinations had two or more disorders. This finding is important because if a child reports auditory hallucinations it should prompt their treating doctor to consider that the child may have more than one diagnosis."

Professor Mary Cannon adds: "Our study suggests that hearing voices seems to be more common in children than was previously thought. In most cases these experiences resolve with time. However in some children these experiences persist into older adolescence and this seems to be an indicator that they may have a complex mental health issue and require more in-depth assessment."