Ginkgo

Does anyone have advice on Ginkgo as a supplementary treatment?  Some of the posts on this blog mention it, and I recall reading something about it briefly on an ADD newsletter I get, but haven't been able to find anything of substance.  Web searches only really yield info on general memory enhancement and dementia (maybe the non-ADD spouses need to take it LOL!) and I haven't really found anything specifically related to ADD.  My husband takes 18mg Concerta, and I'd like to hear any stories from people on this blog on their experiences.