mrsD has mentioned taurine and Tourette Syndrome above so just wanted to add on here. Bonnie Grimaldi published an hypothesis regarding magnesium deficiency and Tourette Syndrome. She always recommended magnesium taurate. My undersanding on my very basic level is that the taurine was less "excitatory" than other forms of magnesium so has a more calming affect on neuromuscular excitability.

http://www.ncbi.nlm.nih.gov/pubmed/11863398
Med Hypotheses 2002 Jan;58(1):47-60.