Abstract
Background Persistent formal thought disorder (FTD) is a core feature of schizophrenia. Recent cognitive and neuroimaging studies indicate a distinct mechanistic pathway underlying the persistent positive FTD (pFTD or disorganized thinking), though its structural determinants are still elusive. Using network-based cortical thickness estimates from ultra-high field 7-Tesla Magnetic Resonance Imaging (7T MRI), we investigated the structural correlates of pFTD.
Methods We obtained speech samples and 7T MRI anatomical scans from medicated clinically stable patients with schizophrenia (n=19) and healthy controls (n=20). Network-based morphometry was used to estimate the mean cortical thickness of 17 functional networks covering the entire cortical surface from each subject. We also quantified the vertexwise variability of thickness within each network to quantify the spatial coherence of the 17 networks, estimated patients vs. controls differences, and related the thickness of the affected networks to the severity of pFTD.
Results Patients had reduced thickness of the frontoparietal and default mode networks, and reduced spatial coherence affecting the salience and the frontoparietal control network. A higher burden of positive FTD related to reduced frontoparietal thickness and reduced spatial coherence of the salience network. The presence of positive FTD, but not its severity, related to the reduced thickness of the language network comprising of the superior temporal cortex.
Conclusions These results suggest that cortical thickness of both cognitive control and language networks underlie the positive FTD in schizophrenia. The structural integrity of cognitive control networks is a critical determinant of the expressed severity of persistent FTD in schizophrenia.
Competing Interest Statement
Conflicts of interest: LP reports personal fees from Janssen, Otsuka Canada, Canadian Psychiatric Association and SPMM Course (UK); investigator-initiated educational grants from Sunovion, Janssen Canada, Otsuka Canada not related to the submitted work. Other authors report no relevant conflicts.
Funding Statement
Funding information: This work was supported by the Wellcome Trust [grant number WT096002/Z/11] and an internal grant from the School of Community Health Sciences, University of Nottingham. LP is supported by the Tanna Schulich Endowment, Academic Medical Organization of South-Western Ontario (Opportunities Fund), Bucke Funds, and Chrysalis Foundation Funds. PFL receives support from the National Institute of Health Research Nottingham Biomedical Research Centre.
Author Declarations
All relevant ethical guidelines have been followed; any necessary IRB and/or ethics committee approvals have been obtained and details of the IRB/oversight body are included in the manuscript.
Yes
All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.
Yes
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Yes
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Yes
Footnotes
Funding information: This work was supported by the Wellcome Trust [grant number WT096002/Z/11] and an internal grant from the School of Community Health Sciences, University of Nottingham. LP is supported by the Tanna Schulich Endowment, Academic Medical Organization of South-Western Ontario (Opportunities Fund), Bucke Funds, and Chrysalis Foundation Funds. PFL receives support from the National Institute of Health Research Nottingham Biomedical Research Centre.
Conflicts of interest: LP reports personal fees from Janssen, Otsuka Canada, Canadian Psychiatric Association and SPMM Course (UK); investigator-initiated educational grants from Sunovion, Janssen Canada, Otsuka Canada not related to the submitted work. Other authors report no relevant conflicts.
Data Availability
Reasonable requests for the anonymised data reported in this manuscript can be made to the corresponding author