Michael - St John's Wort is an herb, used extensively in other countries to treat depression (and sometimes here), no matter from whence it came. I used it for a while, and it took 30 days, to begin to take effect, and it isn't nearly as expensive as prescription anti-depressants. The only thing is, it began to interfere with a med I take for an unrelated cause. I'm not the one with PD, my love has it, but I take two meds, that couldn't be compatible with SJW. Best wishes. Jo Ann