Bilici M, Yildirim F, Kandil S, Bekaroglu M, Yildirmis S, Deger O, Ulgen M, Yildiran A, Aksu H. (2004) Prog Neuropsychopharmacol Biol Psychiatry. 28(1) 181-90.
BACKGROUND: The most commonly used medications for attention deficit hyperactivity disorder (ADHD) are the psychostimulants. There is, however, considerable awareness in alternative, nonstimulant therapies, because some patients respond poorly to stimulants or are unable to tolerate them. Some studies suggest that deficiency of zinc play a substantial role in the aetiopathogenesis of ADHD. Therefore, to assess the efficacy of zinc sulfate we conducted treatment trial.
METHODS: Patients with a primary DSM-IV diagnosis of ADHD (N=400; 72 girls, 328 boys, mean age=9.61+/-1.7) were randomly assigned in a 1:1 ratio to 12 weeks of double-blind treatment with zinc sulfate (n=202) (150 mg/day) or placebo (n=198). Efficacy was assessed with the Attention Deficit Hyperactivity Disorder Scale (ADHDS), Conners Teacher Questionnaire, and DuPaul Parent Ratings of ADHD. Primary efficacy variables were differences from baseline to endpoint (last observation carried forward) in mean ADHDS and Conners Teacher Questionnaire scores between the zinc sulfate and the placebo groups. Safety evaluations included monitoring of adverse events, vital signs and clinical laboratory values.
RESULTS: Zinc sulfate was statistically superior to placebo in reducing both hyperactive, impulsive and impaired socialization symptoms, but not in reducing attention deficiency symptoms, as assessed by ADHDS. However, full therapeutic response rates of the zinc and placebo groups remained 28.7% and 20%, respectively. It was determined that the hyperactivity, impulsivity and socialization scores displayed significant decrease in patients of older age and high BMI score with low zinc and free fatty acids (FFA) levels. Zinc sulfate was well tolerated and associated with a low rate of side effect.
CONCLUSIONS: Zinc monotherapy was significantly superior to placebo in reducing symptoms of hyperactivity, impulsivity and impaired socialization in patients with ADHD. Although by themselves, these findings may not be sufficient, it may well be considered that zinc treatment appears to be an efficacious treatment for ADHD patients having older age and high BMI score with low zinc and FFA levels.
See also the controlled trial by Akhondzadeh et al, 2004, in which zinc sulphate as an adjunct to stimulant medication (methylphenidate) also reduced ADHD symptoms.
It remains to be seen whether the results from this study may generalise to other populations where zinc deficiency may be less likely. Here, although it was found that dietary supplementation with zinc was superior to placebo treatment, the benefits observed remained limited, as the authors note.
Given the variability within the 'ADHD' diagnosis, no single treatment can reasonably be expected to help all individuals with this condition, but there is other evidence to suggest that zinc deficiency may be worth considering.
For a review of studies in this area, see: