Cortical thickness and formal thought disorder in schizophrenia: An ultra high-field network-based morphometry study

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.

Conceptual disorganization and redistribution of resting-state cortical hubs in untreated first-episode psychosis: A 7T study

“…Our observation does not necessarily negate a role for language networks in thought disorders; instead, it provides empirical support for the role of system-level dysconnectivity at restingstate as a determinant of the severity of FTD. Our results are not directly comparable to the results obtained from studies on patients with persistent thought disorder 33,34 . Ketamine challenge which recapitulates acute thought disorder has been reported to increase functional (BOLD) activity in the same medial sensory association cluster where we observed a higher level of bDC among the more disorganized patient group 35 .…”

Acute conceptual disorganization in untreated first-episode psychosis: A combined magnetic resonance spectroscopy and diffusion imaging study of the cingulum

“…Individual differences in cingulum microstructure have been linked to cognitive control measures among healthy individuals 55 as well as in patients with schizophrenia 56,57 . Disrupted connectivity of the cingulum reported here supports the notion that the severity of CD relates to disrupted domaingeneral control aspects of information processing in schizophrenia 58 .…”

Acute conceptual disorganization in untreated first-episode psychosis: a combined magnetic resonance spectroscopy and diffusion imaging study of the cingulum

“…72,73 Disrupted connectivity of the cingulum reported here supports the notion that the severity of CD relates to disrupted domain-general control aspects of information processing in schizophrenia. 32 We found increased GSH levels in patients with a high degree of CD in acute FEP, despite the normal levels of glutamate in the ACC. This association was specific to CD, as nei-ther negative symptom burden nor positive symptom severity was related to GSH concentrations in this sample.…”

“…31 In particular, disorganized thinking was associated with structural variations in the cognitive control regions, more than in language regions. 32 Abnormalities in the structural integrity of the cingulum have been linked to CD by Bopp and colleagues. 7 Finally, given its protracted development compared to other long bundles, 33 the cingulum is considered to be particularly vulnerable to maturational aberrations relevant for schizophrenia.…”