A new study by researchers from the
Johns
Hopkins Children's Center and five other medical
centers concludes that carefully measured low doses of
methylphenidate (Ritalin) are safe and effective for
attention-deficit and hyperactivity disorder in
preschoolers. Investigators warn, however, that 3- to
5-year-olds appear more sensitive to the drug's side
effects, which include irritability, insomnia and weight
loss, than are older children with ADHD and require closer
monitoring.
Children who took the drug also experienced somewhat
slower growth rates. On average, children on the drug grew
half an inch less and gained 2.9 pounds less per year than
expected. Researchers recommend that pediatricians weigh
the risks of slowed growth rates against the benefits of
treatment and that children on long-term treatment be
monitored carefully several times a year to assess growth
changes over time.
Methylphenidate is the most widely prescribed drug for
the treatment of ADHD in children but is not approved by
the Food and Drug Administration for use in children
younger than 6.
Results of the federally funded research, the first
large-scale, long-term study of the safety and value of the
drug in younger children, appear in a special section of
the November issue of the Journal of the American Academy
of Child and Adolescent Psychiatry.
"These results give us the missing links in the
decision to prescribe a drug that's been widely used
off-label in preschool-age children," said Mark Riddle,
director of Child and Adolescent Psychiatry at the
Children's Center and a co-author of the study, which
followed 303 children between ages 3 and 5 over 70 weeks.
"We were able to confirm what many already suspected--that
even lower doses in preschoolers can safely achieve the
desired therapeutic effect and, indeed, that low doses are
often optimal."
Children in the study were started on a low-dose
regimen of medication ranging from 3.75 mg total daily to
22.5 mg total daily. By comparison, the cumulative daily
dose for older children ranges from 15 mg per day to 50 mg
per day. The optimal dose needed to reduce symptoms ranged
widely in preschool-age children, but on average, 14 mg
daily was effective in reining in symptoms.
"One of the surprises was that in some cases doses as
low as even 3 [mg] to 4 mg a day were helpful to some
preschoolers, which goes to show that lower doses need to
be given a chance before higher doses are tried," Riddle
said.
About 11 percent of those enrolled in the study
experienced side effects severe enough to drop out. These
included weight loss, anxiety, skin picking, mood
disturbances and insomnia.
"We want parents to know that trained professionals
can make an accurate diagnosis and prescribe helpful and
safe treatment in preschoolers with ADHD," Riddle said,
"but do expect your prescribing physician to monitor side
effects closely and regularly and to tweak the dose if
necessary."
ADHD is characterized by a wide range of symptoms,
including inability to concentrate, being easily
distracted, fidgeting and restlessness, among others. Left
untreated, ADHD can interfere with academic progress and
social and emotional development. More than 4.4 million
children in the United States have ADHD, according to
estimates by the Centers for Disease Control and
Prevention. About 2 percent of preschool-age children are
believed to have ADHD.
Other Johns Hopkins researchers included Elizabeth
Kastelic; Golda Ginsburg; Margaret Schlossberg; Alexander
Scharko, now at the University of Wisconsin; and Jaswinder
Ghuman, now at the University of Arizona. The study was led
by Laurence Greenhill, of Columbia University and the New
York State Psychiatric Institute. Other study sites were
Duke University, New York University, the University of
California, Los Angeles and the University of California,
Irvine.
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