Effects of iron treatment on cognitive performance and working memory in non-anaemic, iron-deficient girls

Abstract

A randomised, double-blind intervention study is described in which 116 adolescent girls with iron deficiency in the absence of anaemia were randomly allocated to iron treatment or a placebo control group. Both cognitive performance and haematological indices of iron status were assessed before and after an eight week treatment period. The four cognitive tests comprised: Hopkins Verbal Learning Test (HVLT), Stroop Task, Visual Search, and Reading Span Task. Between pre- and post-treatment testing sessions participants in the Iron group showed significant improvement in immediate recall of recently heard words from the Hopkins word lists, while those in the Placebo group showed no improvement. In addition, at post-treatment significant relationships were found between haemoglobin levels and recall of recent words and between serum ferritin levels and reading span. These results suggest: (a) that iron deficiency may impair the performance of everyday activities that involve verbal working memory, and (b) that improvement in iron status may bring about an improvement in verbal working memory performance.