Grant: CIHR Fellowship

Psychotic depression is a severe psychiatric disorder in which psychotic symptoms (e.g. delusions, hallucinations) emerge during a major depressive episode. Compared to non-psychotic depression, psychotic depression is associated with longer recovery times and an increased risk of suicide. Resting-state functional magnetic resonance imaging (R-fMRI) has been used to examine functional connectivity in brain networks and previous studies have demonstrated relationships between functional connectivity and treatment outcomes. The default mode network (DMN) refers to a set of brain regions that demonstrate functional connectivity with each other. The DMN has been studied extensively in non-psychotic depression and a recent study from our group is the first to specifically examine the DMN in psychotic depression. This preliminary study demonstrates that patients who remit from psychotic depression have replicable patterns of abnormal functional connectivity between the DMN and other brain regions involved in sensory processing. This abnormal functional connectivity may be associated with sustained remission (when patients remain well and are symptom free) or relapse (when patients become acutely ill again with a new episode of psychotic depression). We propose to extend our preliminary findings into the full neuroimaging dataset and examine longitudinal DMN functional connectivity. This novel R-fMRI project will also assess whether changes in functional connectivity are associated with the subgenual cingulate, a brain region that has been consistently implicated in severe depression. The discoveries made in this project will directly impact the lack of neurobiological knowledge about psychotic depression. This study will also allow biomarkers to be associated with treatment outcomes with the goal of advancing clinical practice by using neuroimaging to guide treatment decisions.