Stimulant Medications for ADHD

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Although the research evidence suggests that medication is effective alone, and may be the most effective part of comprehensive multimodal management (Wilens and Biederman 1992; Greenhill 1992), it is the general consensus that educational and behavioural strategies add to the success of management and are essential if medication is ineffective.

There is considerable pressure to treat ADHD with its disruptive symptoms, associated learning, behavioural and emotional problems, family stress, and possible persistence into adolescence and adulthood. For a minority the outcome is antisocial behaviour, criminality and substance abuse. The multiplicity of aetiology, heterogeneity of presentations, changes over time, and intervention and range of possible treatments, make management complex and confusing. Approaches to diagnosis and treatment are not equally validated and support is compromised by the lack of, or long waiting lists for, support services. This context emphasises the use of medication which can have powerful short-term benefits for disrupted behaviour and performance.

The need for medication and its effectiveness is relative to the nature and severity of problems and the use of other interventions. A multimodal approach, especially with educational and behavioural supports, should be used if available. Although medication is the most effective short-term treatment for the disruptive behaviours of ADHD, other approaches may add to the success of medication and be essential if medication is ineffective.

Comprehensive assessment and management is emphasised in managing ADHD. Day-to-day support for the vulnerable individual at home, and in other settings, should be provided. Management is, however, complex and time consuming and requires collaboration. Medication, whilst the best validated of the various interventions, is likely to be better accepted when accompanied by advice regarding other supports. Referral to supports should be vigorously pursued, though other services may be scanty (Hazell, McDowell, Walton et al 1996). The prescribing of medication is exclusive to the medical practitioner, but few can provide intensive, prolonged behavioural and emotional management. ADHD usually requires, among other services, psychological or psychiatric support.

North American practice and research dominates paediatric psychopharmacy, particularly in ADHD, reflecting the prevalence of disruptive behaviours responding to medication. The stimulants are methylphenidate, which is most studied, and dexamphetamine, which is less so, and other medications are used (Werry 1994). A very recent extensive review by Spencer, Biederman, Wilens et al (1996) describes medication in the treatment of ADHD for children and adults. This refers to 155 controlled studies in over 5700 individuals documenting the efficacy of stimulant medications. Other authors have stated that stimulants are safe and effective drugs (Gadow 1992) and have few side-effects when used in children under proper medical supervision (Werry 1988).

The place of medication may decrease in importance as other vulnerabilities in the child or the childâs environment are dealt with, and as the child moves away from the threshold of the disorder. Indeed, stimulant medications have been shown to have similar types of effect in children with diagnosed ADHD and individuals regarded as normal controls (Peloquin and Klorman 1986; Rapoport, Buschsbaum and Monte 1980; Rapoport, Buschsbaum and Zahn 1978). These results emphasise that the diagnosis of ADHD cannot be determined by a positive response to medication.

Stimulant medication

Pharmacology and stimulant use

Medications for many disorders act on immature or inefficient neurotransmitters, which are localised or distributed throughout the brain, and which have widespread effects on performance and behaviour (Gadow 1992; Rogeness, Javors and Pliska 1992; Werry 1988). There have been reports of mutations in dopamine transporter genes, which may predispose to ADHD (Cook, Stein, Krakowski et al 1995) or in receptor genes (Ebstein, Novick, Umansky et al 1996). There is, however, no single neurocognitive defect that accounts for ADHD or which can be corrected by a single medication or intervention (Matochik, Liebenauer, King et al 1994).

Dexamphetamine and methylphenidate (Ritalin¨) act on dopaminergic and noradrenergic neurotransmitter pathways and appear to influence mainly prefrontal, frontal and limbic systems with benefits on disruptive behavioural inhibition, impulse control, selective attention, active working memory and executive functioning. There is no Îparadoxical effectâ of Îstimulantâ appearing to Îsedateâ disruptive behaviour. There are no direct effects on consciousness or moral judgement (Greenhill 1992; Wilens and Biederman 1992).