Konofal E, Lecendreux M, Arnulf I, Mouren MC. (2004) Arch Pediatr Adolesc Med. 158(12) 1113-5.
BACKGROUND: Iron deficiency causes abnormal dopaminergic neurotransmission and may contribute to the physiopathology of attention-deficit/hyperactivity disorder (ADHD).
OBJECTIVE: To evaluate iron deficiency in children with ADHD vs iron deficiency in an age- and sex-matched control group.
DESIGN: Controlled group comparison study. SETTING: Child and Adolescent Psychopathology Department in European Pediatric Hospital, Paris, France. PATIENTS: Fifty-three children with ADHD aged 4 to 14 years (mean +/- SD, 9.2 +/- 2.2 years) and 27 controls (mean +/- SD, 9.5 +/- 2.8 years).
MAIN OUTCOME MEASURES: Serum ferritin levels evaluating iron stores and Conners' Parent Rating Scale scores measuring severity of ADHD symptoms have been obtained.
RESULTS: The mean serum ferritin levels were lower in the children with ADHD (mean +/- SD, 23 +/- 13 ng/mL) than in the controls (mean +/- SD, 44 +/- 22 ng/mL; P < .001). Serum ferritin levels were abnormal (
CONCLUSIONS: These results suggest that low iron stores contribute to ADHD and that ADHD children may benefit from iron supplementation.
Iron deficiency is known to cause problems with attention and concentration, learning disabilities, poor motor coordination and motor restlessness.
Iron is important in the metabolism of dopamine – a substance which plays a key role in many brain signalling systems. The stimulant drugs used to treat ADHD are thought to help because they increase dopamine levels.
In this study, iron stores (serum ferritin) were found to be significantly lower in children with ADHD – in fact, they had only half as much stored iron as the control group. Abnormally low ferritin was found in more than 4 out of 5 ADHD children, but less than 1 in 5 of the control children. Actual blood levels of iron, however, were still in the normal range (i.e. these children were not anaemic).
Importantly, ADHD symptoms (inattention, hyperactivity and impulsivity) were more severe in the ADHD children with lower iron stores. The researchers calculated that low iron could explain around 30% of the variability in ADHD symptoms.
These findings suggest that routine testing for low iron stores in ADHD would be worthwhile. Testing is very important - because either too little or too much iron can cause problems.
In those children with ADHD who have low iron stores, supplementation with iron might be helpful - as some very small open studies have already indicated - but properly controlled trials would be needed to confirm this, as the current authors recommend.
However, getting more iron from the diet is usually a better method of increasing iron stores than supplementation, whenever this is possible. (This can most easily be done simply by eating more red meat).
For more information on the possible role of iron in ADHD symptomatology, see: