KEEPING the dose of stimulant medication as low as possible in adolescents with attention deficit hyperactivity disorder may counteract their slower rate of physical development, according to the authors of a new study published in this week’s MJA. (1)
Paediatricians from the Sydney Medical School Nepean and the Westmead Children’s Hospital found that stimulant medication treatment lasting more than 3 years resulted in significantly lower body weight, height and body mass index in adolescents with ADHD.
“We found that, in boys who had taken stimulant medication for ADHD for a minimum of 3 years until age 12.00-13.99 years, there was lower weight but comparable growth in height and pubertal development compared with controls”, the study said.
“Subjects aged 14.00-15.99 years were significantly behind the controls in their growth in height and pubertal development, with an inverse relationship between the dose of medication and height velocity.
“These findings suggest that stimulant medication delays the rate of maturation during puberty, including the timing of the peak height velocity, but not the onset of puberty.”
Study coauthor Dr Alison Poulton, a clinical senior lecturer at Sydney Medical School Nepean, told MJA InSight treatment for ADHD remained a balancing act between positive and negative effects.
“The thing about puberty is that it’s so variable, even within one family”, she said.
“We have to look at the treatment’s consequences. Is the medication helping ease the suffering enough to mitigate the consequences of the medication?
“The question of treatment affecting pubertal development is perhaps even more emotive as delay may be associated with significant psychopathology”, Dr Poulton said.
She said a delay in the rate of physical maturation during puberty could have social implications for teenage boys with ADHD as they might be less tall and less well developed than their peers.
“The treatment should be determined by whether or not it is helping the child. If the problem is bad enough, you consider the treatment even if there are consequences”, Dr Poulton said.
The study authors wrote that one positive aspect to the delaying effect of the stimulant medication was the “slower rate of weight gain”.
A consultant paediatrician told MJA InSight that adults with untreated ADHD were more likely to be obese, so if stimulant medication slowed the rate of weight gain, adolescents with treated ADHD were less likely to grow into obese adults.
The paediatrician, who preferred to remain anonymous because “it’s a controversial subject”, said a bone-age analysis would have been a useful addition to the study.
“If their bone age was down after stimulant medication treatment it would indicate that they have some room to grow and that once off the stimulant, or on a lower dose, they would catch up”, he said.
The study reiterated the notion that the negative impact of stimulant medication on growth had reached its maximum by 3 years of treatment.
“This could be reassuring for children who may have been on treatment for 7 years or more by the time they reach puberty”, the study authors wrote. “Similarly, intermittent treatment appeared to bestow no advantage for growth.”
As low a dose as therapeutically possible remained the best solution for teenagers with ADHD, the study concluded.
“It is important to use the lowest dose that is compatible with therapeutic efficacy, so that an adequate growth rate is maintained”, the authors wrote.
– Cate Swannell
Posted 21 January 2013