It&#x27;s not so much ineffective as insufficiently effective. At least for mood disorders, most patients need to try more than one treatment regimen before finding one that works (in the sense of having a sustained and appreciable reduction in symptoms without intolerable side effects), and a substantial minority never find a treatment regimen that they&#x27;re satisfied with. The biggest study on this  that I know of is STAR*D, which focuses on depression treatments [1].<p>[1] <a href="http:&#x2F;&#x2F;www.edc.gsph.pitt.edu&#x2F;stard&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.edc.gsph.pitt.edu&#x2F;stard&#x2F;</a>