Schizophrenia has been considered to be one of the most complex mental disorders with a wide range of cognitive, emotional, and social function impairments at both behavioural and neural levels. Recent clinical diagnostic manual developed by the American Psychiatric Association, the DSM-5, has also highlighted a new conceptualization of classifying schizophrenia as a psychotic spectrum disorder with a continuum of different behavioural and neural manifestations that also share and overlap with other related disorders.
Clinically, it has been reported that high prevalence of comorbidity of schizophrenia with other mental disorders such as obsessive compulsive disorder (OCD). Empirical evidence has also suggested patients with comorbidity of schizophrenia and OCD have unique brain structure and functional changes associating with poorer prognosis and functional outcome. However, there are only limited studies examining the neural mechanism of these patients, and none of them have attempted to compare patients with schizophrenia, OCD, and patients with comorbid schizophrenia and OCD directly with matched healthy controls. It is still largely unknown for the underlying brain connectivity between these three clinical samples.
To bridge such a gap of knowledge, Dr. Raymond CHAN from the Neuropsychology and Applied Cognitive Neuroscience (NACN) Laboratory, CAS Key Laboratory of Mental Health, the Chinese Academy of Scienceshas worked with the local and international collaborators to specifically examine the resting-state functional connectivity (rsFC) changes between default mode network (DMN) sub-regions and whole brain voxels in these clinical patients. They scanned the brains of 22 patients with schizophrenia comorbid with OCD (SOC), 20 patients with schizophrenia, 22 patients with OCD, and 22 healthy controls and analyzed the rsFC in these participants.
Their findings showed that patients with SOC exhibited the highest rsFC strength within sub-regions of the DMN and the lowest rsFC strength between the DMN and sub-regions of the Salience Network (SN) compared with the other three groups. Moreover, when compared with HCs, all the patients with schizophrenia, OCD, and SOC were found to show increased rsFC between sub-regions of the DMN and the Executive Control Network (ECN). Patients with SOC and pure schizophrenia diagnosis both exhibited increased rsFC between sub-regions of the DMN and the middle temporal gyrus, but patients with pure OCD exhibited decreased rsFC between them. These ﬁndings provide additional information for clinicians and researchers to understand the shared and unique underlying functional connectivity exhibited by patients with schizophrenia, OCD, and SOC. In particular, these findings highlight a specific alteration in functional connectivity in the DMN in patients with SOC, and provide new insights into the dysfunctional brain organization of different mental disorders. Dr. Chan’s team is now working on a set of cognitive and emotional measures as well as task-based functional neuroimaging methods to systematically compare and contrast these clinical patients. The research findings will finally guide for the development of a precision brain science approach for clinical diagnosis and intervention psychosis spectrum disorders and OCD.
This study was supported by the National Key Research and Development Programme, the Beijing Municipal Science & Technology Commission Grant, the Beijing Training Project for the Leading Talents in Science & Technology, the Strategic Priority Research Programme (B) of the Chinese Academy of Science, and the CAS Key Laboratory of Mental Health.
The paper is now available from Schizophrenia Bulletin
Wang, Y. M., Zou, L. Q., Xie, W. L., Yang, Z. Y., Zhu, X. Z., Cheung, E. F. C., Sørensen, T. A., Møller, A., Chan, R. C. K.* (2018). Altered functional connectivity of the default mode network in patients with schizo-obsessive comorbidity: A comparison between schizophrenia and obsessive-compulsive disorder. Schizophrenia Bulletin, DOI: 10.1093/schbul/sbx194