Ok, this is not as good a reference as my original references, but here is one showing protection of the brain from glutamate toxicity by estrogen. http://www.springerlink.com/content/h88p5450j0384nmm/ If you want to look for other studies (and there are other ones, better ones), the keywords to look for are "NMDA receptors" and you are looking for things that don't depolarize them. There is a magnesium ion protecting the NMDA receptors, protecting them from a calcium influx which kills brain cells. If you have a magnesium deficiency you will be prone to this. You can get a magnesium deficiency even if you supplement plenty of magnesium if you (1) eat a high protein diet since the breakdown product of protein is ammonia and it takes magnesium and BH4 to eliminate ammonia via the urea cycle. So the ammonia will bind up the magnesium and outstrip your supply. (2) If you have genetic issues creating BH4 (as I do) ammonia can build up and it will depolarize the magnesium on the NMDA receptors (actually strip it off) and leave the receptors wide open to damage. There may be other things that strip that magnesium away -- I did not mean to imply by making a list that I studied the whole issue -- just my problem regarding it. But estrogen fixes it. I take DHEA to make my own estrogen and it does the job. (I mean you don't need a prescription to ward off glutamate toxicity). P.S. I take 1g. of magnesium/day and I still almost died of glutamate toxicity before I went on DHEA. It is because I have 3 genes lowering BH4 (so genetically you may need more than magnesium but it is a good start).