Does extended medication with amphetamine or methylphenidate reduce growth in hyperactive children?

The purpose of the present study was to examine growth in children on extended stimulant treatment. Ninety-one hyperactive boys were studied, of whom 68 were treated with amphetamine and 23 with methylphenidate. The age range was 3-10 years. All children were treated with one of these stimulants for a minimum of 1 year. The yearly mean values for height and weight were all between the 25th and 90th percentile of the population norms. During the 1st year of treatment children who used amphetamine showed significantly smaller weight gains than those who used methylphenidate (F = 6.9, df = 64, P < 0.05). Four patients (17%) in the methylphenidate group and 21 (31%) in the amphetamine group had a weight loss during the 1st year, ranging from 0 to 9.5 kg. Within this group of 25 patients there was a significantly higher number of children with a pretreatment weight greater than that of the 50th percentile group (chi-square = 5.59, P < 0.05). All 25 patients showed sufficient weight gain at later examinations. Multiple regression analyses showed that neither cumulative doses nor age had a significant effect on growth when initial weight and height were controlled for. These findings indicate that, for most children, extended treatments with amphetamine or methylphenidate do not have negative effects on growth. However, some children show weight loss during the 1st year of treatment, more often when amphetamine is used. Among those children who may show reduced weight gain, most are above mean weight before treatment begins.