Mg depletion, particularly in the hippocampus, appears to represent an important pathogenic factor in Alzheimer's disease. It is associated with high aluminium incorporation into brain neurones. This type of Mg deficit cannot respond to mere Mg supplementation, but requires correction of the dysregulation inducing this Mg depletion. Further research should seek to control the alterations of albumin, which may induce this brain Mg depletion.