The goal of this clinical trial is to compare two active types of transcranial magnetic stimulation in two nicotine-using populations: nicotine-using people with psychosis and nicotine-using people without a diagnosis of a psychotic disorder. The main questions it aims to answer are: 1. Can rTMS change functional connectivity in brain circuits associated with nicotine use? 2. Are those rTMS-induced changes in functional connectivity related to craving? Participants will complete tasks assessing their cognitive performance and craving before and after each week of TMS. Researchers will compare the effect of each TMS intervention on participants with and without psychosis to see if one type of TMS has an effect on nicotine craving.
This study proposes to test the hypothesis that the brain circuits most relevant to nicotine use in schizophrenia are distinct from pathways identified in nicotine-using people without psychosis. This study seeks to provide evidence that targeted stimulation of the Default Mode Network (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 left dorsolateral prefrontal cortex (L DLPFC) leads to these changes in nicotine-using people without psychosis. The investigators will test this hypothesis in a crossover design comparing 1) DMN-targeted continuous theta burst stimulation (cTBS) and 2) L DLPFC-targeted intermittent theta burst stimulation (iTBS). cTBS and iTBS are types of rTMS. cTBS has inhibitory effects and reduces functional connectivity, while iTBS is excitatory and increases connectivity (Huang et al. 2005). By applying cTBS to the DMN, a target that modulates craving in schizophrenia, the investigators expect DMN connectivity to decrease, thereby decreasing craving. Excitatory stimulation (e.g. iTBS) to the L DLPFC reduces craving in smokers without psychosis (Tseng et al. 2022). This study will test a model that integrates brain network pathophysiology and cognition to 1) explain the prevalence of nicotine 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. Aim 1: Target Engagement: Determine if rTMS manipulates functional connectivity of each target (DMN, L DLPFC) (n=60). Hypothesis 1A: Functional connectivity of the entire DMN will decrease after 5 days of DMN-targeted cTBS. Hypothesis 1B: Functional connectivity of the L DLPFC to the left insula will increase after 5 days of L DLPFC-targeted iTBS. As an exploratory hypothesis, the investigators will test if there is an effect of diagnosis on connectivity change. Aim 2: Clinical Efficacy: Determine if rTMS affects cue-induced craving and if craving change correlates with change in functional connectivity (n=60). Hypothesis 2A: Both DMN-targeted and L DLPFC-targeted rTMS will significantly reduce craving. Hypothesis 2B: Craving change will be correlated with functional connectivity change. As an exploratory hypothesis, in individuals with schizophrenia, DMN-targeted cTBS will be more efficacious than L DLPFC-targeted iTBS. Aim 3: Determine if individual differences in rTMS-induced network connectivity change are explained by individual differences in network controllability (n=60). There is significant heterogeneity in individual response to rTMS, even with network-targeted approaches. This may be related to network controllability, a metric of the average input energy required to change brain state (Bassett and Sporns 2017). It is critical to understand predictors of network change for optimal rTMS target selection in clinical trials. Hypothesis 3: Individual differences in rTMS-induced change in DMN connectivity will be associated with average controllability of the DMN rTMS stimulation site.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
90
rTMS is a technique of TMS that allows the selective external manipulation of neural activity in a non-invasive manner. During TMS, a rapidly changing current is passed through an insulated coil placed against the scalp. This generates a temporary magnetic field that in turn induces electrical current in neurons and allows the modulation of neural circuitry. The combination of rTMS with functional magnetic resonance imaging allows the selective targeting and modulation of brain networks. The repeated application of rTMS can cause long term changes in behavior and task performance that is reflected in altered brain network connectivity.
Vanderbilt University Medical Center
Nashville, Tennessee, United States
Resting-state functional connectivity
The investigators will evaluate the effect of DMN-targeted cTBS on functional connectivity of the left parietal node of the DMN and the entire default mode network. The investigators will also evaluate the effect of L DLPFC-targeted iTBS on functional connectivity of the L DLPFC.
Time frame: Baseline to one week, and three weeks to five weeks
Cue-induced craving
The investigators will evaluate the effect of DMN-targeted cTBS and L DLPFC-targeted iTBS on self-reported craving before and after presentation of visual nicotine cues. Craving is measured on a scale from 0 to 10, with 10 being the highest level of craving.
Time frame: Baseline to one week, and three weeks to five weeks
Tiffany Brief Questionnaire of Smoking Urges (QSU)
The investigators will evaluate the effect of DMN-targeted cTBS and L DLPFC-targeted iTBS on QSU scores. The QSU-Brief has a range of 10-70, with higher scores indicating higher smoking urges.
Time frame: Baseline to one week, and three weeks to five weeks
Self-reported craving
The investigators will evaluate the effect of DMN-targeted cTBS and L DLPFC-targeted iTBS on self-reported craving, measured by a Visual Analog Scale of nicotine craving. Craving is measured on a scale from 0 to 10, with 10 being the highest level of craving.
Time frame: Baseline to one week, and three weeks to five weeks
Wisconsin Smoking Withdrawal Scale (WSWS)
The investigators will evaluate the effect of DMN-targeted cTBS and L DLPFC-targeted iTBS on self-reported withdrawal symptoms.The WSWS has a range of 0-112, with higher scores indicating higher withdrawal.
Time frame: Baseline to one week, and three weeks to five weeks
Fagerstrom Test for Nicotine Dependence (FTND)
The investigators will evaluate the effect of DMN-targeted cTBS and L DLPFC-targeted iTBS on nicotine dependence severity. The FTND has a range of 0-10, with higher scores indicating greater nicotine dependence.
Time frame: Baseline to one week, and three weeks to five weeks
Self-reported nicotine use
The investigators will evaluate the effect of DMN-targeted cTBS and L DLPFC-targeted iTBS on self-reported nicotine use, measured by the Timeline Follow Back and the Recent Substance Use Questionnaire.
Time frame: Baseline to one week, and three weeks to five weeks
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