Experts addressing a recent conference at the Institute of Psychiatry in London warned that a tenth of children under five might be harboring a serious psychiatric illness .
In more than 11 % of cases, the children suffered symptoms bad enough to disrupt their daily lives, and failure to spot and treat these conditions early might be cause of unnecessary distress and suffering.
In a stunning revelation, Dr Adrian Angold, from Duke University in North Carolina, told the conference that large numbers of pre-school children meet the criteria for mental and behavioral disorders seen in school-age children, adolescents and adults.
In the survey, psychiatrists asked the parents of 307 pre-school children to fill in questionnaires. The questions were cautiously designed to spot telltale behavioral traits commonly associated with different kinds of mental illness and disability.
The researchers found that about 17 % met standard criteria for having a mental disorder. Many of the children were found to have an array of problems, often displaying symptoms of more than one kind of disorder.
The children were found to suffer from depression, serious disruptive behaviour, attention deficit hyperactivity disorder (ADHD) and anxiety, including generalized fear, phobias and terror at being separated from parents. Children with depression showed typical symptoms of sadness, irritability, disturbed sleep and lack of appetite.
Older children with similar difficulties were held back at school, socially isolated and unable to forge relationships.
Dr Angold believes that early intervention is a must for screening and treatment of these disorders in babies and infants.