Food and Behaviour Research

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Zinc in attention-deficit/hyperactivity disorder.

Arnold LE, DiSilvestro RA (2005) J Child Adolesc Psychopharmacol.  15(4) 619-27. 

Web URL: View this and related abstracts via PubMed here

Abstract:

OBJECTIVE: The aim of this study was to review the published evidence for a role of zinc nutrition in attention-deficit/hyperactivity disorder (ADHD).

METHOD: A computer literature search was supplemented by the authors' knowledge.

RESULTS: Numerous controlled studies report cross-sectional evidence of lower zinc tissue levels (serum, red cells, hair, urine, nails) in children who have ADHD, compared to normal controls and population norms. A few studies show correlations of zinc level with either clinical severity or a change thereof in response to stimulant or chemical challenge. Two placebo-controlled trials--one of zinc monotherapy, the other of zinc supplementation of methylphenidate--reported significant benefit. However, diagnostic procedures and sample representativeness were often not clear, and most such reports have come from countries and cultures with different diets and/or socioeconomic realities than are found in the United States (only one American sample in nine published reports). In particular, both positive clinical trials of zinc supplementation came from the Mid-East (Turkey and Iran), an area with suspected endemic zinc deficiency. The largest of these trials used zinc doses above the recommended upper tolerable limit and had a 2 in 3 dropout rate.

CONCLUSION: It is not clear how well the accumulating evidence for a possible role of zinc in ADHD applies to middle-class American children. However, the evidence appears strong enough to warrant further controlled study in well-diagnosed samples representative of the socioeconomic spectrum. Hypothesis-testing clinical trials are needed of this potential treatment that, if found effective, might become a relatively safe, cheap substitute for, or adjunct to, current treatments in some patients. At present, it should remain an investigational treatment.

FAB RESEARCH COMMENT:

As this review notes, the two randomised controlled trials of zinc supplementation for ADHD to date have involved Middle Eastern populations, which may limit their generalisability. See:

As these authors point out, however, there is now sufficient other evidence linking ADHD with zinc deficiency to merit serious investigation - especially as there are suggestions that zinc status could affect the response to other treatments, including stimulant medication. See