A study in Northern Ireland has found that almost half of children in care suffer behavioural difficulties, while some inflict self-harm.
The study tracked 388 children under the age of five who were being looked after by the state between March 2000 and 2002.
There was a high rate of behavioural problems such as temper tantrums and bed wetting among the children, while a number of self-harm incidents were also detected, said Ms Wendy Cousins, of the Institute of Child Care Research at Queen's University in Belfast.
One of the most distressing incidents observed during the study involved a four-year-old girl who tried to slash her wrists. The youngster later made a full recovery.
Ms Cousins said it was rare to see instances of self-harm in children of such a young age but the instances of behavioural problems had risen from 24 per cent to 47 per cent during the two-year study. "The fact that children this young are causing themselves harm is a serious concern," she said.
Ms Cousins said the vast majority of children in the care of social services came from extremely troubled family backgrounds.
A total of 77 per cent of their families had a history of alcohol abuse, 74 per cent were affected by domestic violence, 64 per cent were touched by mental illness, half had a history of offending behaviour and 42 per cent were affected by drug abuse.
The study carried out by the Institute of Child Care Research argued that in recent decades awareness of the physical and sexual abuse of children had grown, but neglect was more common and its dangers should also be highlighted.