Brain iron plays a crucial role in neuronal function. Although brain iron represents less than 2% of total body iron, homeostasis of iron is mandatory for normal physiological brain function. Iron plays an important role in various proteins and enzymes which are involved in neurotransmitter synthesis and the myelination of the axons of motor neurones; such iron-containing enzymes include tryptophan hydroxylase (serotonin synthesis) and tyrosine hydroxylase (dopamine synthesis) as well as the being the precursors of adrenaline and noradrenaline.

Although systemic iron homeostasis has been elucidated over the past decade,¹  its regulation within the brain is still unclear. Figure 5.1 summarizes our current understanding of iron homeostasis in the brain.²