Depression is a very common disorder that is most often chronic or recurrent in nature. Many subjects do not respond adequately to an initial antidepressant treatment trial. Subjects who do not respond adequately to multiple therapeutic interventions are considered to have treatment-resistant depression (TRD). Among the treatment options for subjects with TRD is Vagus Nerve Stimulation (VNS) Therapy.This blinded, randomized, multicenter controlled study is intended to collect evidence that VNS Therapy as an adjunctive therapy improves health outcomes for patients with TRD.

The purpose of this study is to determine whether a new medical technology can help reduce post-operative total knee or hip pain when combined with a Cognitive-Behavioral intervention (CBI).

This new medical technology, is called transcranial direct current stimulation (tDCS), it uses a very small amount of electricity to temporarily stimulate specific areas of the brain thought to be involved in pain reduction. The electrical current passes through the skin, scalp, hair, and skull and requires no additional medication, sedation, or needles.

This study will investigate the effects of tDCS, the Cognitive-Behavioral (CB) intervention and their combination on pain among veterans following total knee arthroplasty (TKA) or total hip arthroplasty (THA). You may benefit in the form of decreased pain and opioid requirements following your knee or hip replacement surgery. However, benefit is only likely if you are randomized to one of the 3 (out of 4) groups.

This study hopes to determine the effects of these interventions and their combined effect on post-operative pain, opioid use and functioning during the 48-hour post-operative period following a total knee or hip replacement.

This study will examine the neural circuitry associated with craving, behavioral disinhibition, and threat-reactivity. The study will involve 2 visits. During the first visit, participants will complete questionnaires and interviews in a private room and do some tests to measure alcohol use. During the second visit, participants will complete a neuroimaging scan of their brain.