Increased Connectivity Between the Nucleus Accumbens and the Default Mode Network in Patients With Schizophrenia During Cigarette Cravings

Abstract

Objective: Compared to the general population, tobacco smoking cessation rates are lower in populations with schizophrenia. Unfortunately, the potential neurophysiologic mechanisms underlying these low cessation rates in schizophrenia have been seldom studied using functional neuroimaging. Recently, it has been shown that tobacco cravings are increased in smokers with schizophrenia compared to smokers with no comorbid psychiatric disorder. Given the critical role of the brain reward system in the neurobiology of addiction, we sought to examine the functional connectivity of core regions of this system in smokers with schizophrenia during the viewing of appetitive smoking cues. Methods: Smokers with (n = 18) and without (n = 24) schizophrenia were scanned using functional magnetic resonance imaging while viewing appetitive cigarette images. Functional connectivity analyses were performed using the bilateral nucleus accumbens as the seed regions. Results: Smokers with schizophrenia and smokers with no psychiatric comorbidity did not differ in subjective cravings in response to appetitive smoking cues. However, in smokers with schizophrenia relative to control smokers, we found an increased connectivity between the nucleus accumbens and regions involved in the default mode network (e.g., middle temporal gyrus and precuneus), which are involved in self-referential processes. Moreover, a positive correlation was observed between the left nucleus accumbens and left middle temporal gyrus connectivity and cigarette cravings across both groups of smokers. Conclusions: These results highlight a key role of the nucleus accumbens in cigarette craving in schizophrenia and suggest that the subjective valuation of cigarette cues is increased in this population. Similar neurofunctional studies on cravings for other psychoactive substances in schizophrenia are warranted.

KEYWORDS:

• Schizophrenia
• cigarette
• nucleus accumbens
• functional connectivity

Acknowledgments

SP is holder of the Eli Lilly Canada Chair on schizophrenia research and a supported member from the Fondation de l'Institut Universitaire en Santé Mentale de Montréal; AD is holder of a Junior 1 Young investigator salary award from the Fonds de Recherche en Santé du Québec

Disclosure statement

AD and SP are holders of grants from Otsuka Pharmaceuticals and HLS Therapeutics unrelated to the current study. AD received speaking honoraria from HLS Therapeutics. JRD and CF declare no potential conflict of interest. None of the authors have any additional income to report.

Funding

The study was funded by a grant from the Fonds de Recherche en Santé du Québec to SP, and the Eli Lilly Canada Chair in schizophrenia research.