Precision Brain Stimulation to Reduce Cannabis Craving in Schizophrenia

The central hypothesis is this: Brain circuits most relevant to cannabis use in schizophrenia are distinct from pathways identified in healthy controls who use cannabis. This study seeks to provide evidence that targeted stimulation of the DMN leads to both altered network activity and a concomitant behavioral change in cue-induced craving and cognitive performance in individuals with schizophrenia and schizoaffective disorder, while targeted stimulation of the L DLPFC leads to these changes in healthy controls who use cannabis. This study will test a model that integrates brain network pathophysiology and cognition to 1) explain the prevalence of cannabis use in schizophrenia and 2) identify a target for engagement in schizophrenia. This study seeks to establish a neuroscientific framework to guide future treatment-oriented studies aimed at reducing craving and improving cognitive performance in individuals with schizophrenia and schizoaffective disorder. This is a study of the effect of 2 rTMS interventions on functional connectivity and craving in individuals with schizophrenia or schizoaffective disorder and healthy controls who use cannabis. Aim 1: Target Engagement: Determine if rTMS manipulates functional connectivity of each target (DMN, L DLPFC) (n=100). Aim 2: Clinical Efficacy: Determine if rTMS affects cue-induced craving and if craving change correlates with change in functional connectivity (n=100). As an exploratory analysis, the factors that explain individual variance in rTMS-induced connectivity change will also be explored.