Researchers conducted psychiatric assessments on 2,500 children between the ages of 11 and 16 and found that 23 percent of children age 11-13 heard voices. As the children got older, the number dropped to 7 percent.
The auditory hallucinations varied from hearing a sentence now and then to hearing full conversations that could last for several minutes, according to the study.
It may present like screaming or shouting and other times it could sound like whispers or murmurs, Dr. Ian Kelleher, study coauthor and researcher at the Royal College of Surgeons in Ireland, told the Australian Associated Press. It varies greatly from child to child, and frequency can be once a month to once every day.
Hearing voices is typically associated with mental illnesses such as schizophrenia or mania. Though the exact cause is unknown, certain areas of the brain are more active in patients who hear voices. These areas could cause the brain to not recognize its voice as its own, according to 2007 study.
Of the 23 percent of 11-13 year olds who heard voices, approximately 50 percent would be diagnosed with a non-psychotic disorder, such as depression. Those who heard voices as they got older were much more likely to be diagnosed with a mental health condition -- almost 80 percent of 13-16-year-olds who heard voices were diagnosed with a psychological problem.
In most cases these experiences resolve with time, Mary Cannon, study coauthor and professor of psychiatry at the Royal College of Surgeons, told the AAP. 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.
For the majority of younger children, the voices do not indicate any serious underlying condition, nor do they manifest into any kind of serious disorder, according to the study.
However, for the other children, these symptoms turned out to be a warning sign of serious underlying psychiatric illness, including clinical depression and behavioral disorders, like attention deficit hyperactivity disorder, Kelleher told BBC News.
The study shows that hearing voices is much more common in children than previously thought, the researchers said. It's important to know if your child is hearing voices because even if it continues into an older age, it could be indicative of a psychological condition.
Psychotic symptoms are important risk markers for a wide range of non-psychotic psychopathological disorders, the researchers wrote. These symptoms should be carefully assessed in all patients.
The British Journal of Psychiatry published the study on Thursday.