It's been known for at least the past year that the drug Ketamine (Special-K being one of its street monikers) significantly improves symptoms of severe depression. And it does so in hours to days rather than weeks or months as with most anti-depressants. Now it looks like the key to its activity may have been found. Since this is a subject near, if not dear to my heart, I did a search to find supplements that might help increase BDNF. The first one I found was for curcumin (a type of spice). Got that from the wikipedia page on BDNF which referenced this article. I'm not recommending this. I don't even know if it would have the desired effect. I'm just putting it out there as a possible lead. Interesting side note: High levels of BDNF seem to be associated with increased itching in eczema. (also from the wiki article).