The stress caused by maltreatment greatly impacts the developing brain of very young children, leading to calls for improved early intervention.

Children exposed to abuse and neglect from a very young age are already at a severe disadvantage when they start school because of the impact the stress has on their rapidly developing brains, research shows.

An Australian study conducted in collaboration with the NSW Department of Family and Community Services has found maltreated children are three times more likely to have 'developmental vulnerabilities'.

"The children are already showing vulnerabilities in psycho-social development. What we mean by that is that they are already showing social, emotional and cognitive vulnerabilities when they start school," says lead researcher UNSW Associate Professor Melissa Green.

"It's like you are starting school without the tools to get going," Professor Green told AAP.

The concerning findings, have led to calls for government funding to be directed to early detection and early intervention for children who are maltreated.

Researchers from Neuroscience Research Australia and UNSW used data from 68,000 children in NSW, of whom 2000 had been exposed to substantiated reports of maltreatment between birth and five years of age.

Of the 2000, more than 22 per cent had experienced more than one type of maltreatment.

Child maltreatment, sometimes referred to as child abuse and neglect, includes all forms of physical and emotional ill-treatment, sexual abuse, neglect and exploitation.

Professor Green says maltreatment can have a critical impact on a child because the first five years of life is one of rapid brain development.

"Exposure to maltreatment during this period where brain elasticity is at its peak may critically impair developmental achievements and learning opportunities, with potential ramifications for cognitive and educational outcomes, as well as social development," she said.

Without early intervention, many maltreated children may not only struggle through school but potentially go on to develop a mental illness.

"Childhood maltreatment is severely over-represented among people with mental illness in adulthood," Prof Green said.

Intervening early will help these children reach their full potential, she said.

"If you could detect early the children who have been maltreated and the children who are showing these vulnerabilities at school entry you would hope to be able to bring them back on to a typical trajectory of school development.

"Again, we are not sure you can do that but the idea is that the brain is very plastic up until age 25 and so the earlier you help to fix the foundation the more likely the next stages of development will get back on track."