Investigating structural subdivisions of the anterior cingulate cortex in schizophrenia, with implications for treatment resistance and glutamatergic levels.

Background: Abnormalities in the anterior cingulate cortex (ACC) are thought to play an important role in the pathophysiology of schizophrenia. Given regional variations in ACC structure, the present study aimed to examine ACC structural subdivisions and their relationships to treatment resistance and glutamatergic levels in schizophrenia.
Methods: This study included 100 patients with schizophrenia and 52 healthy controls from 2 cohorts. We applied non-negative matrix factorization to identify accurate and stable spatial components of ACC structure. Between groups, we compared ACC structural indices in each spatial component based on treatment resistance or response and tested relationships with ACC glutamate + glutamine levels.
Results: We detected reductions in cortical thickness and increases in mean diffusivity in the spatial components on the surface of the cingulate sulcus, especially in patients with treatment-resistant and clozapine-resistant schizophrenia. Notably, mean diffusivity in these components was higher in patients who did not respond to clozapine compared to those who did. Furthermore, these ACC structural alterations were related to elevated ACC glutamate + glutamine levels but not related to symptomatology or antipsychotic dose.
Limitations: Sample sizes, cross-sectional findings and mixed antipsychotic status were limitations of this study.
Conclusion: This study identified reproducible abnormalities in ACC structures in patients with treatment-resistant and clozapine-resistant schizophrenia. Given that these spatial components play a role in inhibitory control, the present study strengthens the notion that glutamate-related disinhibition is a common biological feature of treatment resistance in schizophrenia.
Competing Interests: Conflict of interest: E. Plitman has received research support from an Ontario Graduate Scholarship (OGS), a Canadian Institutes of Health Research (CIHR) Canada Graduate Scholarship–Master’s, a CIHR Vanier Canada Graduate Scholarship and the Healthy Brains for Healthy Lives Postdoctoral Fellowship. Y. Iwata has received fellowship grants from the CIHR, research support from the Japan Society for the Promotion of Science, the Japanese Society of Clinical Neuropsychopharmacology, Inokashira Hospital Grants for psychiatry research, manuscript fees from Dainippon Sumitomo Pharma and speaker’s fees from Eli Lilly, Meiji-Seika Pharma, Mochida Pharmaceutical and Yoshitomi Yakuhin within the past 3 years. Y. Noda has received a Grant-in-Aid for Young Scientists (KAKENHI); research grants from AMED; an investigator-initiated clinical study grant from Teijin Pharma Ltd.; research grants from the Japan Health Foundation, the Meiji Yasuda Mental Health Foundation, the Mitsui Life Social Welfare Foundation, the Takeda Science Foundation, the Senshin Medical Research Foundation, the Health Science Center Foundation, the Mochida Memorial Foundation for Medical and Pharmaceutical Research, the Taiju Life Social Welfare Foundation, and Daiichi Sankyo Scholarship Donation Program; and equipment-in-kind support for an investigator-initiated study from Magventure Inc, Inter Reha Co., Ltd., Rogue Resolutions Ltd. and Miyuki Giken Co., Ltd. H. Uchida has received grants from Eisai, Otsuka Pharmaceutical, Dainippon-Sumitomo Pharma, Mochida Pharmaceutical, Meiji-Seika Pharmaceutical and Novartis; speaker’s honoraria from Otsuka Pharmaceutical, Eli Lilly, Shionogi, Pfizer, Yoshitomi Yakuhin, Dainippon-Sumitomo Pharma, Meiji-Seika Pharma, MSD and Janssen Pharmaceutical; and advisory panel payments from Dainippon-Sumitomo Pharma within the past 3 years. M. Mimura has received research support from the Japan Society for the Promotion of Science and grants or speaker’s honoraria from Daiichi Sankyo, Dainippon-Sumitomo Pharma, Eisai, Eli Lilly, Fuji Film RI Pharma, Janssen Pharmaceutical, Mochida Pharmaceutical, MSD, Nippon Chemipher, Novartis Pharma, Ono Yakuhin, Otsuka Pharmaceutical, Pfizer, Takeda Yakuhin, Tsumura and Yoshitomi Yakuhin within the past 3 years. A. Graff-Guerrero has received research support from the following external funding agencies: CIHR, the US National Institutes of Health, the Ontario Mental Health Foundation, the National Alliance for Research on Schizophrenia and Depression, Mexico Instituto de Ciencia y Tecnología del Distrito Federal, Consejo Nacional de Ciencia y Tecnología, the Ministry of Economic Development and Innovation of Ontario, the Ontario Academic Health Science Center Alternate Funding Plan Innovation Fund and the W. Garfield Weston Foundation. M. Chakravarty has received research funding from the Weston Brain Institute, the Alzheimer’s Association and the Michael J. Fox Foundation. He is currently receiving support from the CIHR, the National Sciences and Engineering Research Council of Canada and McGill University’s Healthy Brains for Healthy Lives Initiative. He is an associated editor of JPN, but was not involved in the review or decision to accept this paper for publication. S. Nakajima has received grants from the Japan Society for the Promotion of Science, AMED, the Japan Research Foundation for Clinical Pharmacology, the Naito Foundation, the Takeda Science Foundation, the Uehara Memorial Foundation and the Daiichi Sankyo Scholarship Donation Program within the past 3 years, as well as research support, manuscript fees or speaker’s honoraria from Dainippon Sumitomo Pharma, Meiji-Seika Pharma, Otsuka Pharmaceutical, Shionogi and Yoshitomi Yakuhin within the past 3 years. No other competing interests declared.
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