Prolonged treatment (more than 3 years) with stimulant medication was associated with a slower rate of physical development during puberty. To maintain adequate height velocity during puberty, we recommend keeping the dose as low as possible.

ObjectiveChildren treated with stimulant medication for attention deficit hyperactivity disorder (ADHD) often lose weight. It is important to understand the implications of this during growth. This prospective study was designed to quantify the changes in body composition and markers of bone metabolism on starting treatment.Methods34 children (29 boys) aged 4.7 to 9.1 years newly diagnosed with ADHD were treated with dexamphetamine or methylphenidate, titrating the dose to optimise the therapeutic response. Medication was continued for as long as clinically indicated. Body composition and bone density (dual-energy X-ray absorptiometry) were measured at baseline, 6 months and 3 years; changes were analysed in Z-scores based on data from 241 healthy, local children. Markers of bone turnover were measured at baseline, 3 months and 3 years.ResultsFat loss of 1.4±0.96kg (total fat 5.7±3.6 to 4.3±3.1kg, p<0.001) occurred in the first 6 months. There were significant reductions over 3 years in the sex and height corrected Z-scores for lean tissue, bone mineral content, bone mineral density and ratio of central to total fat (−0.84±0.86, p=0.003; -0.55±0.31, p<0.0001; -0.41±0.28, p<0.0001 and −0.55±0.62, p=0.006 respectively). Propeptide of type I collagen indicated a significant reduction in bone turnover after 3 months (564±202 to 458±96ng/ml, p=0.019), which was fully recovered after 3 years (619±276ng/ml).ConclusionsStimulant medication was associated with early fat loss and reduced bone turnover. Lean tissue including bone increased more slowly over 3 years of continuous treatment than would be expected for growth in height. There was long-term improvement in the proportion of central fat for height. This study shows that relatively minor reductions in weight on stimulant medication can be associated with long-term changes in body composition. Further study is required to determine the effects of these changes on adult health.

Stimulant medication is known to cause transient weight loss and slowing down of growth, but whether it delays physical maturation is unclear. We studied growth and bone age over the first 3 years of treatment in children with attention-deficit/hyperactivity disorder (patients) compared with healthy siblings (controls). Bone age was estimated blindly by two independent radiologists using Tanner and Whitehouse version 3. Dexamphetamine or methylphenidate was titrated and continued when clinically indicated. Forty out of 73 patients, together with 22 controls, completed the study. There were no significant growth differences between the two groups at baseline. Despite slower growth on treatment [5.1 cm/year, 95% confidence interval (CI): 4.7–5.5, vs. 6.3 cm/year, 95% CI: 5.7–6.8, P=0.002; and 2.7 kg/year, 95% CI: 2.1–3.3, vs. 4.4 kg/year, 95% CI: 3.5–5.3, P=0.005], the patients showed no significant maturational delay (RUS score: 49 U/year, 95% CI: 44–55, vs. 55 U/year, 95% CI: 47–63, P=0.27). A subgroup of patients underwent serial biochemistry and dual-energy X-ray absorptiometry, recording a significant reduction in fat (5.61±3.56–4.22±3.09 kg, P<0.001) and leptin (3.88±2.87–2.57±1.94 ng/ml, P=0.017). The pattern of change in height z-score over time was modified by the dose of medication (P for interaction=0.024). We found no medication effect on the rate of maturation, which was instead predicted by baseline leptin (P=0.035 controlling for age and sex).