Even a mild head injury can have long-term effects on children, researchers have warned.
Head injuries 'can affect personality'
University of Warwick experts asked parents what differences they had seen in their children after an injury.
The Journal of Neurology, Neurosurgery, and Psychiatry study, found they emotional, behavioural and learning problems and personality changes.
The researchers said many children received no follow-up after hospital treatment for head injuries.
They studied over 500 children aged 5 to15 years old who suffered head injuries over a six-year period.
Parents were asked to register how their child had changed after the head injury, and what follow-up they had received from clinicians.
They found that, even after a mild head injury, parents said one in five children had a change in personality, often describing the difference as "like having a different child".
Forty-three per cent of children with mild head injury had behavioural or learning problems that led to them being described as having a "moderate disability".
Among children with more serious head injuries, about two thirds had moderate disability, and about half experienced a major change in personality after the head injury.
All of those studied had been treated in a hospital after their head injury, but only a third of parents said that doctors at the hospital had made a follow-up appointments for their child.
The researchers also found that teachers were only aware of the children's injuries in only 40% of cases studied.
Dr Carol Hawley, from Warwick Business School at the University of Warwick, who carried out the study, said: "Many children with mild injury do not receive routine follow-up after discharge home from hospital, yet a significant proportion of them do have some lasting problems which may affect their behaviour and ability to learn.
"This could put them at a disadvantage at school."
The researchers are currently developing a questionnaire for doctors to send to parents after children with head injury are sent home from the hospital.
They say that would allow children found to be at risk of problems to be offered a follow-up assessment, and if necessary, a referral to an educational psychologist or community paediatrician.
Lisa Turan, chief executive of the Child Brain Injury Trust (CBIT) said: "It is no surprise to me that the children identified in this study have received little or no follow up after head injury.
"The difficulties they speak of indicate a growing need for improved services."