Fig. 1

Performance of cognitive tests reflecting interactions of MAOA genotype (low or high transcription rates) and dietary iron (iron sufficient (IS) or iron deficient (ID). a, b Performance is similar in the two genotype groups with an iron-sufficient diet, but diverges with iron deficiency. c, d Performance differs in the two genotype groups with an iron-sufficient diet but converges with iron deficiency. In all 4 tasks, the direction of the effect of ID is consistent within genotype group, increasing performance measures in the hi-MAOA group and decreasing them in the low-MAOA group. * indicates statistically significant genotype by ID interaction