[Role of iron in the treatment of attention deficit-hyperactivity disorder]

Abstract

Introduction: The aetiology of attention deficit hyperactivity disorder (ADHD) is attributed to different factors: genetic, environmental, and biological (neurotransmitters: dopaminergic system). Iron is essential for the correct functioning of the dopaminergic system. Iron deficiency is common in patients with ADHD, and its correction may be useful in the treatment.

Objectives: To analyse a possible relationship between iron deficiency and symptoms of inattention, hyperactivity and impulsivity in ADHD patients, and the potential benefit of iron therapy.

Patients and methods: A prospective study was conducted on non-anaemic and cognitively normal children, newly diagnosed with ADHD, according to DSM-IV criteria. Specific scales were used (SNAP-IV, ADHS) and serum ferritin was determined. Those with ferritin ≤ 30 ng/ml were treated with ferrous sulphate (4 mg/kg/day) for 3 months, with its effect quantified being subsequently quantified.

Results: A total of 60 patients, with a mean age of 9.02 years (range: 6-14), were analysed. The inattentive subtype was the most frequent one (53.3%). Almost two-thirds (63.3%) had iron deficiency, which was more frequent among the inattentive group (38 vs 22, P<.02). The iron treatment was completed by 17 patients. The treatment was not effective in 7 of the 8 non-inattentive subtypes, with a partial response in the remaining one. Of the 9 inattentive subtypes: the treatment was successful in the total control of symptoms in 5 of them, partially effective in other 3, and ineffective in one patient. The probability of complete response after treatment with iron was higher in inattentive patients with ADHD (P=.02).

Conclusions: Treatment with iron supplements can be an effective alternative to treat patients with ADHD and iron deficiency, especially the inattentive subtype.

Keywords: Attention deficit hyperactivity disorder; Dopamina; Dopamine; Ferritin; Ferritina; Hierro; Iron; Restless legs syndrome; Síndrome de piernas inquietas; Trastorno por déficit de atención e hiperactividad.