The proposed study aims to 1 (Aim 1) identify dysfunctions in neurocircuitry that engender irritability, and (Aim 2) determine how changes in neurocircuit function related to change in irritability. We will accomplish Aim 1 with resting-state and frustrative nonreward (FNR) task-based fMRI data from n=30 HCs and n=60 subjects with MDD ((Fig 3). For Aim 2, we will randomize the MDD cohort (n=60; same as Aim 1) to 2 weeks of twice-weekly 40-minutes long intravenous infusion of either ketamine (0.5 mg/kg) or midazolam (0.02 mg/kg) in a double-blind parallel-arm fashion, and by repeating clinical assessments and fMRI scans after the last infusion. The central hypothesis of the proposed study is that striatum is a key hub in the neurocircuitry of irritability, and that treatment-related improvement in irritability is associated with normalization of these neurocircuit functioning.
The study is investigating dysfunctions in neurocircuitry in regards to irritability with healthy controls (HC) and individuals with Major Depressive Disorder (MDD) by performing MRIs. The MDD group will also be randomized to receive ketamine or midazolam to investigate changes post-treatment in neurocircuitry with regards to irritability.