A Novel Therapeutic Mechanism for Nicotine Craving in Schizophrenia

Tobacco use is a leading cause of mortality in schizophrenia, but treatments are partially effective. Default mode network (DMN) pathology is linked to tobacco use in schizophrenia, and transcranial magnetic stimulation (TMS) applied to the DMN affects craving in schizophrenia. To advance TMS therapeutics for tobacco use in schizophrenia, we used TMS experiments to 1) determine optimal stimulation parameters then 2) compare our optimal parameters against a well-established, effective TMS intervention for craving.

In Protocol Optimization TMS, nicotine-using individuals with schizophrenia (n=10) received single sessions of DMN-targeted TMS with pre/post neuroimaging and craving assessment. Neuroimaging analysis revealed bilateral parietal DMN connectivity was associated with craving change. In Comparative Effectiveness TMS (n=62), nicotine-using individuals with schizophrenia and non-psychosis controls participated in a crossover study comparing DMN-targeted and left dorsolateral prefrontal cortex (DLFPC)-targeted TMS with pre/post neuroimaging and craving assessment. Mixed effects models were used to determine effects of target, group, and relationship between craving change and connectivity change.

In Protocol Optimization TMS, increased craving was associated with increased bilateral parietal DMN connectivity (mean pFDR<0.012, r=0.60). In Comparative Effectiveness TMS, both interventions reduced craving (DLPFC: p=0.0015; DMN: p=0.0054) and bilateral parietal DMN connectivity (DLPFC: p=0.024; DMN: p=0.022). There was an interaction of bilateral parietal DMN connectivity change, group, and age (p=0.001) where connectivity change was associated with craving change in older individuals with schizophrenia (p=0.041) but not other groups.

Bilateral parietal DMN connectivity is a novel mechanism underlying craving in schizophrenia that can be engaged for therapeutic benefit.