Attention deficit hyperactivity disorder

Editor, – We were most concerned to read Dr Hazell's statement ('Letters' Aust Prescr 1996;19:5) that 'The important take home message ... is that clinicians, educators and parents should not expect conduct or learning problems to respond to stimulants in the absence of ADHD'. This comment perpetuates the myth that a response to stimulant medication confirms the diagnosis of ADHD. Medications which alter the balance of neurotransmitters in the brain modify symptoms, not diagnoses. Stimulants, like most centrally-acting medications, do not obey any particular diagnosis-therapy couplings. As there is considerable overlap in symptom complexes between the various disruptive behaviour syndromes of children, as well as with other emotional disturbances, there is no logical basis for assuming that the effects of stimulants are married to any particular diagnosis. In fact, it has been shown that even 'normal' children often demonstrate improvements in cognitive performance and behaviour when given stimulants.¹ These somewhat unpalatable truths strike at the very heart of the on-going debate regarding the reasonable and proper use
of these medications.

Certainly, there is now a large body of research evidence that the majority of children with ADHD display clinically significant and often dramatic improvements in impulse control, sustained attention, task completion, compliance and social acceptability when treated with stimulants. However, children with other related problems may also show response. We feel it is important that discussion be informed by what is known from the literature rather than biased by misinformation.

Dr Daryl Efron
Dr Rick Jarman
Paediatricians Centre for Community Child Health & Ambulatory Paediatrics Royal Children's Hospital Melbourne, Vic.

Dr P. Hazell, the author of the article on attention deficit hyperactivity disorder (Aust Prescr 1995;18:60-3), comments:

Drs Efron and Jarman have inferred from my comments in a previous letter that I consider stimulant responsiveness to validate the diagnosis of ADHD. This is not my view, and such a view could hardly be sustained in the presence of the significant placebo response seen in samples of children with ADHD. However, I am grateful to the correspondents for raising the question of whether children with behavioural or academic problems in the absence of ADHD may derive clinically significant benefit from treatment with stimulants, since this has prompted me to look further into the issue.

Treatment studies of children without comorbid ADHD are rare, but one inpatient study of 22 conduct-disordered adolescent males (15 of whom were reported not to have comorbid ADHD) found a greater decrease in aggressiveness in response to methylphenidate than to placebo.² The authors cautioned that there was improvement in only some aspects of the conduct problems, but the findings do suggest a treatment effect independent of ADHD. In the light of these findings, I accept that the specific comment I made, at least in relation to conduct disorder, should be tempered. I have not been successful in locating any treatment study that demonstrates an effect on learning disorder or disability independent of effects on ADHD symptoms. Perhaps the readership can help me with this.