New research on iron and Alzheimer's disease is absolutely fascinating.  If you have too high a level of iron, it exacerbates the disease; lowering iron levels in affected persons helps.  But too little iron chronically can also apparently be a factor in developing the disease ... 

Read the research here

and remember :  if you are a man check your iron levels before using supplements at any age.  If you are a woman, once you have stopped menstruating, the same advice holds good.