Zinc Supplementation for ADHD
Supplementing Methylphenidate with Zinc to Treat Childhood ADHD
What is the problem and what is known about it so far?
Attention-deficit hyperactivity disorder (ADHD) occurs early in childhood and is characterized by inattention, hyperactivity, and impulsiveness. It is the most common behavioral childhood disorder, affecting approximately 3-7% of school-age children. Current information suggests that certain vitamin and mineral deficiencies including zinc are associated with ADHD. The hormone melatonin, which requires zinc for its production, helps regulate the neurotransmitter dopamine and the sleep cycle of children with ADHD. Decreased dopamine levels in the brain may cause ADHD symptoms. Although psychostimulants are the most commonly used medications to treat ADHD, some patients respond poorly to or cannot tolerate them. Thus there is a need to explore other treatment options for ADHD.
Why did the researchers do this particular study?
This study examined the effects of zinc coupled with conventional medication. Researchers wanted to assess the benefits of prescribing supplementary zinc (a mineral) with methylphenidate (Ritalin) in treating children with ADHD. Earlier Middle Eastern research reported that zinc sulphate alone reduced symptoms in ADHD patients, especially those with low zinc levels.
Who was studied?
44 outpatient children (26 boys and 18 girls) ages 5-11 from Roozbeh Psychiatric Hospital in Tehran, Iran newly diagnosed with ADHD and who had not taken medication for their condition before enrolling in this study. None had known psychiatric disorders, mental retardation, or chronic medical conditions.
How was the study done?
During the six-week trial, half the children took zinc sulphate (55mg/day) plus methylphenidate; the other half took a placebo of sugar (55mg/day) plus methylphenidate. A child psychiatrist assessed the children’s condition every two weeks.
What did the researchers find?
The researchers found that the children’s behavior in both study groups improved throughout the trial. The children taking zinc supplements, however, showed greater improvement in their condition after six weeks, compared with those taking the placebo. Nausea may have been more common in the children taking zinc sulphate, but the findings were inconclusive. The majority of children taking supplementary zinc complained about its metallic taste.
What were the limitations of the study?
The limitations of this study included the small number of participants, use of only a moderate dose of methylphenidate, short follow-up period, and lack of plasma zinc concentration.
What are the implications of the study?
Zinc sulphate plus methylphenidate increase the improvement rate of children with ADHD. Past studies have suggested a link between zinc deficiency and the pathophysiology of ADHD. The findings in this study may reflect a benefit from zinc replacement or from additional zinc as body zinc was not documented. More research on a greater number of participants and with different zinc dosages is needed to validate the positive effects of zinc supplements in children with ADHD.
Summarized by Kimberley Cullen, College of Medicine, University of Vermont
Summarized from “Zinc Sulfate as an Adjunct to Methylphenidate for the Treatment of Attention Deficit Hyperactivity Disorder in Children: A Double Blind and Randomized Trial”. Akhondzadeh, S. et al. BMC Psychiatry, April 8, 2004. Volume, Number 9.
