Failure to respond to drugs with a 5-HT2 mechanism when added to SSRI including nefazodone, trazodone, mirtazapine/mianserin, SSRI + atypical neuroleptics (clozapine, risperidone, olanzapine, ziprasidone) at therapeutic doses for 4 weeks or longer. (the SSRI must be at clinically appropriate doses and the 5-HT2 antagonist must be at doses that antagonize a significant % of receptors (trazadone greater than 125 mg, nefazodone greater than 300 mg, mirtazapine greater than 30 mg, clozapine greater than 50 mg, risperidone greater than .5 mg, olanzapine greater than 5mg, ziprasidone greater than 20 mg).