Some health boards have admitted they are even scrambling to fund treatment other than the prescription of drugs for the psychiatric and neurobehavioural disorder.
Official guidelines say sufferers should be offered psychological help and their parents behaviour management training – but investment appears to vary around the country.
Youngsters with the condition, which tends to emerge before the age of seven, have short attention spans, are hyperactive or suffer both traits. It affects 5% of school-aged children, with the severest form afflicting 1.5%.
Healthcare Improvement Scotland (HIS), which carried out the research, said services in the 14 health boards in Scotland were stretched despite it admitting that the number of youngsters identified as suffering from ADHD falls "far short of what we would expect".
The internal health watchdog added that while it has identified some improvements in the care of sufferers and their families since the last review four years ago, many issues remain.
It said: "There is no doubt that the provision of care for ADHD is changing for the better, but there is still some way to go to make sure that all children, young people and adults with ADHD can easily access the support and services that they need."
Estimates suggest around 5200 children have been diagnosed with the problem north of the Border – less than 1% of under 18s. This indicates thousands are living with the condition without any support.
The proportion of children diagnosed varies massively in different parts of the country and is particularly low in NHS Greater Glasgow and Clyde (GGC) and NHS Lanarkshire.
Despite this, HIS found pressure on resources was a problem in NHS GGC and guidelines on treating patients had not been fully met.
In other areas, services appeared to be under even greater strain.
In NHS Lothian, parenting groups had to be suspended this year for staff to catch up on the number of children who needed assessment and follow-up appointments, the report said. In NHS Highland there was a "lack of capacity to deliver scheduled parenting programmes" in some communities. Challenges providing "non-pharmacological" treatments were blamed on high caseloads in Tayside, and on resource issues in Forth Valley and Grampian.
Dr Premal Shah, who leads a working group on ADHD in adults for the Royal College of Psychiatrists in Scotland, said psychological and behavioural therapies were meant to be the first line of treatment and that these made a big difference to families.
He said: "In general, health boards are struggling to deliver in many areas of mental health care and my understanding is that delivering non-pharmacological approaches for ADHD is one of those areas. That is quite a common problem."
Hazel McLinden, fundraising co-ordinator for Brighter Days, an ADHD support group in West Lothian, said she had to wait seven months after her daughter, Eve, was diagnosed before attending a parenting course and the nine-year-old had been waiting to see a play therapist for nine months.
But she said some parents who attended Brighter Days had not been offered this support.
She said: "A lot of our parents will decide to come to us because there is not an awful lot [of help] once you are diagnosed. Apart from medication, you are pretty much on your own." She said she hoped the report would raise awareness, adding: "They will grow into adults but they will not grow out of the condition."
Dr Chris Steer, a consultant paediatrician for NHS Fife with a particular interest in ADHD, said: "The picture of ADHD services across Scotland is extremely variable. In a children's and young people's context the diagnostic rates differ markedly from area to area."