TUCSON, ARIZ. – Two new studies support the use of methylphenidate in treating hyperactivity in children with autism.
The results contradict much of the historical data showing that psychostimulants are not helpful in this population but confirm what many psychiatrists are using in clinical practice for autism and autism spectrum disorders.
In the first study, 11 preschool children with autism received gradually titrated doses in an open-label fashion with methylphenidate hydrochloride 1.25–10 mg twice daily after a 1-week lead-in phase. Then the children were randomized to their optimal dose for 2 weeks and placebo for 2 weeks, in either order. The children ranged in age from 41 months to 72 months; the mean age was 5 years.
Methylphenidate was successful in reducing the hyperactivity/impulsivity subscale of the Conners' Parent Ratings Scale and the Children's Global Assessment Scale. Further analysis of the double-blind data is needed, but the results of the open-label phase are encouraging, author Dr. Jaswinder K. Ghuman said at a psychopharmacology conference sponsored by the University of Arizona.
“These children have many problems, so parents and teachers feel that any small improvement is worth it, even though the response is not as robust as in children without developmental disabilities,” Dr. Ghuman said in an interview. “With a small improvement, they are more manageable in the classroom, and able to benefit from other psychosocial and educational interventions.”
There were seven mild to moderate adverse events, including reduced appetite (in 2 patients), sleepiness or feeling tired (2), difficulty sleeping (2), and mood lability (1).
None of the events led to discontinuation of the medication but did lead to dose increases being limited, which may have made the response less robust, said Dr. Ghuman of the psychiatry department at the University of Arizona, Tucson, and director of its infant and preschool program.
Anecdotal reports have linked psychostimulants with a high frequency of adverse events. Children with autism may be more likely to respond to stimulants with irritability, mood lability, and worsening of stereotypic and repetitive behaviors, so care needs to be exercised in starting the children at a low dose, with relatively slower titration and frequent regular monitoring, she said.
In a recent separate, double-blind, placebo-controlled crossover study, adverse events led to the discontinuation of methylphenidate in 13 (18%) of 72 children with autism and hyperactivity (Arch. Gen. Psychiatry 2005;62:1266–74). Doses in the study were based on patient weight and ranged from 7.5 mg/day to 50 mg/day in divided doses.
Methylphenidate was superior to placebo in reducing scores on the teacher-rated hyperactivity subscale of the Aberrant Behavior Checklist, with effect sizes ranging from 0.20 to 0.54 depending on the dose and rater.
Overall, 35 (49%) of the 72 children were classified as methylphenidate responders. The placebo response rate was 20%.
Popular belief is that children with a lower IQ and younger children do not respond as well to methylphenidate. But there was no difference in response because of IQ level below or above 50 points, a diagnosis of autism or Asperger's disorder, or age, which ranged from 5 years to 14 years.
Further study is needed to replicate these findings and to see whether they could be generalized to the everyday clinical setting, Dr. Ghuman said.