 - Nonresponse to adequate trial of both study medications i.e., 4weeks on escitalopram 30 mgd, and imipramine 200 mgd; patients having an inadequate response to one study medication could be enrolled and receive the other; patients having responded to an adequate trial of either study medication would be offered a retrial; also excluded will be subjects having non responded to an adequate trial with citalopram i.e., 4 weeks on citalopram 60 mgd 