The world's first study of reactive attachment disorders in schoolchildren has revealed that more than 5000 Scottish youngsters of primary school age or under could have a condition that can cause them to form poor or inappropriate relationships with adults.

The research, which assessed all six and seven-year-old children from 29 primary schools in an area of Glasgow, found that 1.4% had an attachment disorder, which is associated with maltreatment in early childhood. This figure is striking by comparison with the number of children who have an Autism Spectrum Disorder in the UK, estimated at 1%.

Dr Helen Minnis, senior lecturer in childhood and adolescent psychiatry at the University of Glasgow, who led the study, was surprised at the high number of cases her research team discovered. She said: "One of the things we were interested in discovering was the prevalence of Reactive Attachment (RAD) Disorder which is a lot higher than we thought.

"It has been described as a very rare disorder and my suspicion is that is probably because we have not been able to look for it properly."

She added: "There have been large and very good studies which looked at child mental health in the UK, but no study has managed to include RAD because they didn't previously have a measure for it."

On the basis of Dr Minnis's research, of Scotland's 378,000 children aged under 12 around 5300 could have Reactive Attachment Disorder, a figure she acknowledges.

Dr Minnis, who will be discussing her findings at a conference on Attachment, Relationships and Behaviour in Schools in Glasgow on June 14, explained that the often-chaotic lifestyles of the families where cases tend to be found make it harder for psychological services to intervene, even when the parents welcomed any support: "What worries me is there are a fair number of children who are a huge burden for themselves, their families and in the classroom but services are not able to catch up with them. It is a hidden population. The sooner we can intervene, the better."

"We felt that some of the families were keen for their children to be referred to childhood mental health services but it was very difficult to have that come to fruition."

However, Dr Minnis does take positives from the situation of many of the children who were identified in the recently completed research, as many are receiving help for other behavioural conditions and 45% are already in foster care.

"We know from our clinical work that RAD is associated with abuse and neglect and in some ways it is reassuring to know that almost half of these children are living with substitute families."

She added: "Of those children we identified, all of them had at least one other disorder, more than half had a likely diagnosis of ADHD, and about a third had a likely diagnosis of conduct disorder."

While Dr Minnis emphasised not all children who had been maltreated by their carers would have RAD, she added that all children who had the condition will have been abused or neglected, with the condition in some children exacerbated by a genetic element.

She said: "It looks like it is a mixture of genes and environment so that some children are more susceptible than others; but you can still only get it if you have been maltreated. I think often parents who maltreat their children have had great difficulty in their own childhood. Also we know that children with RAD are more likely to have parents who had the disorder Maybe their parents had other psychiatric problems when they grew up, making it more difficult to look after their children as well."

While the area of Glasgow where the study was conducted is high on the social deprivation scale, Dr Minnis doesn't think this factor would distort her results, as the mental health of the local population was comparable with the rest of the country.

"The picture we got was that if you looked at the population as a whole, they were quite similar to children in the rest of the UK in terms of their mental health, but there was a tiny minority of children who had these quite severe and complex problems, particularly with social relationships.

"So I think that figure of 1.4% might be a bit less in some areas [of the country] and a bit more in others."

This view is not shared by Marion McLeod, senior policy and parliamentary officer for Children in Scotland, as she believes the living conditions of the residents of an area of high social deprivation could have an adverse affect on the ability of some of them to be good parents.

"I don't think the findings in Glasgow could be extrapolated to the rest of Scotland," she said. "Social and material disadvantage do impact on people's parenting, and consequently what you might expect in some areas you couldn't necessarily assume would be true for the rest of Scotland."

Ms McLeod added the way to reduce the number of children with attachment issues would be to improve the quality of service to all under-fives in Scotland.

She said: "If you provide a universal early education and care service that is staffed by graduate-level qualified professionals, the number of children who will be in need of specialised intervention will be far fewer proportionally across the population.

"If this were to happen, the number of children who would come into the clinical category of disorder would be very much lower than the 1.4% we have at present."

Councillor Stephen Curran, Glasgow City Council executive member for education, whose council collaborated with Dr Minnis in her research said: "We have long recognised that some children in the city have difficulty forming relationships, which is why more than 10 years ago Glasgow embarked upon a major investment in nurture groups.

"We have been leading Scotland with the use of nurture groups to meet the needs of the most vulnerable in our primary schools and the council has invested heavily in this initiative.

"They target the needs of children who are in danger of disengaging from education at a very young age. The reductions in exclusions from school and increased attendance are a testament to their success.

"We also have a number of projects to deliver parenting support, such as the highly successful Triple P scheme [Positive Parenting Programme], which is a fundamental element of Glasgow's early intervention approach."