Thousands of hyperactive children are not receiving the care they need, a report suggests.
Around 500,000 British children may have the disorder
The National Attention Deficit Disorder Information and Support Service says doctors are to blame because they are failing to diagnose the condition.
It follows its own survey of 125 hospital doctors across the UK.
It found that over half thought that the condition is underdiagnosed
Attention Deficit Hyperactivity Disorder is caused by an imbalance in some of the brain's chemicals.
It is characterised by hyperactive or impulsive behaviour such as fidgeting, talking excessively and being easily distracted.
The disorder is estimated to affect 5% of school-age children in the UK -
around 500,000 youngsters, with many experiencing symptoms into adulthood.
The National Institute for Clinical Excellence recommended that 1% of children with severe ADHD - around 100,000 - should receive treatment, which includes the use of drugs like Ritalin.
However, according to the NADDIS report just 70,000 children are receiving medication.
Many of the doctors who took part in the survey said a lack of specialists was to blame. Others pointed the finger at GPs, who they suggested were unsure about which patients to refer on.
They also highlighted a lack of knowledge among GPs, parents and teachers about the condition.
The 50 child and adolescent psychiatrists and 75 paediatricians surveyed for the report said undiagnosed and untreated ADHD had serious consequences for
Some 98% said these children would be more likely to drop out of school
earlier, 99% said they would do less well academically and 93% thought they were
more likely to get involved in criminal behaviour.
Andrea Bilbow, director of ADDISS, said: "ADHD is a real condition, which if
not diagnosed and treated can impact a child's whole life - from achieving their
potential at school, to their relationships, self-esteem and their ability to
function in social and family settings.
"Despite growing understanding of the condition among experts, many other
professionals and carers still remain unaware of the condition and the
treatments that are available to help manage it.
"This means that many people do not have access to the support which they
need to cope with a condition that can affect all aspects of their lives."
Almost all (98%) of the specialists questioned thought that behavioural therapy and medication was the most effective treatment of ADHD.
Dr Val Harpin, a consultant paediatrician from Sheffield Children's Trust,
said: "The findings of the report firmly emphasise the need for better
treatment practices and an accurate diagnosis at the earliest stage possible,
and this demands a co-ordinated approach from health, social and education
"At the moment, too many children are 'slipping through the net' and as a consequence, they are simply learning to fail."
ADDISS called for action to improve care for those living with ADHD, greater
support for parents and more education and resources for teachers.