Conditions: Major Depressive Disorder
Keywords: Major Depressive Disorder Cognitive Impairment Partial Response Residual Symptoms
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 35
Healthy volunteers: no

Brief summary:
This study aims to test the effect of a newly-approved stimulant medication, lisdexamfetamine dimesylate (Vyvanse), on specific residual symptoms of depression found in some patients who are undergoing treatment with, but have only partially responded to, a selective-serotonin reuptake inhibitor (SSRI) or selective-norepinephrine reuptake inhibitor (SNRI) antidepressant. Specifically, the investigators hypothesize that symptoms potentially related to deficient dopaminergic activity, such as lassitude, apathy, reduced positive affect and impaired executive function, in particular, will improve. This protocol is designed to test the hypothesis that this cluster of co-occurring residual symptoms sometimes found in treated depression will respond as a group to adjunctive psychostimulant therapy. The investigators propose to demonstrate this cluster of residual depressive symptoms and to measure the effect of stimulant therapy on it. The investigators hope to better understand the specific symptoms in this clinical population that are likely to improve with stimulant therapy.

Detailed description:
This protocol is designed to test the hypothesis that a cluster of co-occurring residual symptoms sometimes found in treated depression will respond as a group to psychostimulant therapy. This cluster includes apathy, reduced drive, fatigue, impaired executive function and other cognitive measures, and low positive affect. We propose to measure this cluster of symptoms in a population of residually depressed subjects demonstrating them, and then to measure the effect of stimulant therapy on this cluster, and each constituent symptom, as well as to measure its effect on subjects' overall functional impairment, and to document treatment emergent adverse effects. The goal is to gather data about the response of these residual symptoms to stimulant therapy. Since each subject will be exposed to active treatment and matched placebo, a benefit to individual participants will be to learn if their specific symptom burden is ameliorated by stimulant therapy, and what adverse effects may emerge for them. We hope to develop an understanding of the specific symptoms in this clinical population that are likely to improve with stimulant therapy. We also hope to be able to characterize the side effect burden of stimulant therapy in this clinical population.

Arms:
arm 1: Participants receive Lisdexamfetamine Dimesylate 20-50 mg capsule each morning for 4 weeks. After a washout period of 2 weeks, they receive Placebo capsule (matching Lisdexamfetamine Dimesylate (Vyvanse) capsule) each morning for 4 weeks. arm 2: Participants receive Placebo capsule (matching Lisdexamfetamine Dimesylate (Vyvanse) 20-50 mg capsule) each morning for 4 weeks. After a washout period of 2 weeks, they receive Lisdexamfetamine Dimesylate capsule each morning for 4 weeks.

Interventions: intervention 1: Lisdexamfetamine Dimesylate (Vyvanse) intervention 2: Placebo
Intervention descriptions: intervention 1: Lisdexamfetamine Dimesylate (Vyvanse) capsules dose ranging from 20mg to 50 mg. intervention 2: Lisdexamfetamine Dimesylate (Vyvanse)-matched placebo capsules.

Protocol document: