The investigators wish to study acute efficacy for 12 weeks on a double blind basis and continued response after open-label treatment at week 24 follow-up. It is important to establish the acute (12 week) efficacy of desvenlafaxine in non-major chronic depression. Also, given that non-major chronic depression is by definition chronic, it is important to demonstrate that benefit persists at follow-up assessment (24 weeks); this is clinically important in trying to alleviate the significant psychosocial morbidity associated with this disorder.
The investigators believe this study will have significant value in the treatment of patients with non-major chronic depression, and will add significantly to what remains an extremely small scientific literature.
The investigators would also like to study the effects of desvenlafaxine on brain structure and function. Learning that a medication reduces symptoms does not teach us how the medication achieves this outcome. Participants in this study can have the opportunity to participate in MRI scanning that will help to understand the mechanisms by with desvenlafaxine is effective. MRI scans are done prior to starting the clinical trial and then again after completing the double blind clinical trial.
