One-fifth of Australian children, many with cold, angry or overprotective parents, are at serious risk of adult mental illness, says a new study.
The findings also reveal that risk factors for adult mental illness are already highly prevalent among infants.
Describing the results as "alarming", the authors say they point to the need for much earlier and more intensive intervention programs to modify the risk factors.
The study, by the Centre for Population Health Research at the University of South Australia, is part of a wider project aimed at working out how adult mental illness can be reduced.
Questionnaire data from the federal government's longitudinal study of 10,640 children was analysed in relation to a list of well-established childhood determinants of mental illness.
"They are essentially adversities that can be faced in childhood, including harsh parenting, financial stresses and parental drug and alcohol use," co-author Professor Leonie Segal told AAP.
The study, published in the Australian and New Zealand Journal of Psychiatry, found about 15 per cent had none of these adversities, while about 20 per cent have at least five factors.
"Negative parenting behaviours were among the most prevalent risks and common among all children," the study found.
"Low parental warmth increased across the age groups so that by the time children were 12-13 years, one in three experienced parenting characterised by low warmth."
Data related to this factor included asking how often a parent hugged their child for no reason.
"If a child is exposed to an angry, non-engaged parent, that's not good for the child but the answer isn't to say that it is the parent's fault," Prof Segal said.
"Parents are carrying a lot of stuff too, they can have their own childhood trauma history which often has not been addressed and that's why they are angry."
Half the infants already had multiple risks, with the most prevalent being parent problematic alcohol use, parent mental illness and mental ill-health during pregnancy.
Two-thirds of children aged 12-13 were regularly exposed to hostile/angry parenting and about 25 per cent of 4-12 year-olds to overprotective parenting.
"We are saying a lot of these things are inter-generational and if we don't put the resources in the right places they won't go away," Prof Segal said.
