Toren P, Eldar S, Sela BA, Wolmer L, Weitz R, Inbar D, Koren S, Reiss A, Weizman R, Laor N. (1996) Biol Psychiatry 40(12) 1308-10.
No abstract is available
Earlier reports had already suggested that zinc deficiency may be unusually common in ADHD or hyperactive children. The aim of this study was to investigate serum zinc in a well-defined clinical sample of ADHD children and matched controls.
The study involved 43 children aged between 6 and 16 years of age (average age 10) who were formally diagnosed with ADHD via a full psychiatric assessment. 90% were male, and 21 were receiving stimulant medication. They were compared with 28 normal children (recruited through a pediatric clinic) who were matched for age and sex.
As predicted, serum zinc levels in the ADHD group were significantly lower than in controls. 30% of the ADHD children had serum zinc values below the minimum values found in the control group - whose values were if anything slightly lower than the norms reported in previous studies. although 2 ADHD children (4.6%) were above the control group range.
Just under one third of these ADHD children therefore showed quite marked serum zinc deficiency. This could not be accounted for by any obvious factors concerning diet or health, nor did the results relate to medication status.
Zinc is an essential co-factor in a huge number of different processes in the brain and body. With respect to ADHD symptoms, the authors point out that zinc deficiencies have been linked with a 'hyperadrenal' syndrome and also with reduced production of melatonin and serotonin, either of which could plausibly contribute to the kinds of behavioural disturbances found in ADHD.
Zinc is an essential nutrient with a very large number of functions. In addition to those highlighted above, zinc is necessary for synthesising complex omega-3 and omega-6 fatty acids within the body.
This was pointed out by Colquhoun and Bunday (1981), who found low zinc levels in many ADHD children surveyed by the UK Hyperactive Children's support group.
Zinc deficiency is therefore likely to lead to (or exacerbate) deficiencies of the complex omega-3 and omega-6 fatty acids that the brain needs unless the diet contains a good direct supply of these.
Other clinical signs of zinc deficiency include white spots on the fingernails, stretch marks on the skin, and reduced sensitivity to taste and smell.
Assessment of zinc status in ADHD would seem sensible, especially since other evidence suggests that zinc deficiencies may also reduce the treatment response to Ritalin. (Arnold et al, 2000).