Research paperCorrelates of poor insight: A comparative fMRI and sMRI study in obsessive-compulsive disorder and schizo-obsessive disorder
Introduction
Insight is defined as the ability of an individual to critically elaborate on his/her mental disorder, such as schizophrenia or obsessive-compulsive disorder (OCD) (APA, 2013). David (1990) differentiated three components of insight into psychosis: recognition that one has an illness, the ability to recognize the symptoms of the illness and the compliance with treatment (David, 1990). Impaired insight is often thought to be related to impaired neurocognitive function, termed as neuropsychological model (Cooke et al., 2005). The cumulative findings seen in several meta-analyses of psychosis revealed mild to moderate associations between poor insight and the neurocognitive domains, including total cognition, intelligence, working memory, verbal memory, non-verbal memory, attention and executive function (Aleman et al., 2006; Nair et al., 2014; Subotnik et al., 2020). Nevertheless, researches in OCD showed that impairment of insight in OCD was only accompanied by impairment of verbal memory (Kashyap et al., 2012; Kitis et al., 2007), conflict resolution/conflict resolution and fluency (Kashyap et al., 2012; Kitis et al., 2007). What's more, no significant difference in the executive functional variables has been reported between OCD with good insight (OCD-GI) and OCD with poor insight (OCD-PI) (Toobaei et al., 2015). It seems that compared with OCD, the range of neurocognitive impairment associated with poor insight is much larger in schizophrenia. Whether the influence of insight on neurocognition is independent of the disease itself. There is no relevant research yet.
Numerous structural neuroimaging studies have described a significant association between impaired insight and multiple structural deficits, while functional MRI studies corroborated structural neuroimaging findings in schizophrenia. These brain areas included the following areas: the prefrontal and cingulate cortices, temporal and parietal lobes, the hippocampi, and cerebellum (Sapara et al., 2014; Xavier and Vorderstrasse, 2016). In particular, poor insight would emerge from impaired function of self-processing areas, including dorsomedial and ventromedial prefrontal cortices, the anterior and posterior cingulate cortices, the anterior insula, the inferior frontal gyrus, and the temporo-parietal junction (Curcic-Blake et al., 2015). White-matter abnormalities in a complex neural circuitry have also been reported to be related to impaired insight in schizophrenia (Antonius et al., 2011; Asmal et al., 2017).
However, there are less researches in OCD. Only a few studies focused on the neuroimaging mechanism of insight in OCD. Reduced spontaneous brain activities in left middle temporal gyrus and right superior temporal gyrus, as well as increased activities in right middle occipital gyrus have been reported associated with poor insight in OCD (Fan et al., 2017b). Decreased cortical thickness of the left superior frontal gyrus, left anterior cingulate cortex, and right inferior parietal gyrus has been reported in OCD-PI (Liu et al., 2019). The aberrant functional connectivity of right anterior insula-right medial orbital frontal cortex has been reported associated with impairment of insight in OCD by a fMRI study (Fan et al., 2017a), while an EEG study suggested no significant different brain functional network characterized by abnormal small-world parameters in OCD-PI compared with OCD-GI (Lei et al., 2017). These findings in OCD are not completely similar to those in schizophrenia studies. Whether this inconsistency is due to the interaction of the insight and diagnosis is still unknown.
The present study was conducted to explore the relationship between insight and clinical, neurocognitive and neuroimaging alterations, and further investigated whether these changes may be insight-specific or diagnosis-related. Previous researchers indicated that obsessive-compulsive (OC) symptoms were independent of psychosis in a sizeable proportion of patients with schizophrenia (Devulapalli et al., 2008; Faragian et al., 2012; Poyurovsky et al., 2007). OC symptoms changed the course and the outcome of schizophrenia, while psychotic symptoms of schizophrenia affected the expression of OC symptoms, accounting for the unique clinical presentation of schizo-obsessive disorder (SOD) (Poyurovsky, 2013). This research on the neural mechanism of insight focused on the insight into illness and OC symptoms, and divides the enrolled subjects into four groups: OCD-GI, OCD-PI, SOD with good insight (SOD-GI), SOD with poor insight (SOD-PI). Amplitude of low frequency (0.01–0.08 Hz) fluctuations (ALFF) and voxel-based morphometry (VBM) were applied independently. ALFF was developed to reflect the regional spontaneous neuronal fluctuations in the BOLD time course (Zang et al., 2007), while VBM offered the opportunity to investigate subtle changes in gray matter volume (Ashburner and Friston, 2000). We speculate that insight is closely related to the clinical symptoms of patients with mental disorder, while the relationship between insight and neurocognition is more affected by disease diagnosis. Besides, insight has its own unique neural mechanism, but partly affected by the specific diagnosis of the disease.
Section snippets
Participants
A total of 111 right-handed patients (81 OCD, 30 SOD) were recruited from the Second Xiangya Hospital of Central South University in Changsha, Hunan, China. Two experienced psychiatrists established diagnoses and comorbidities using Structural Clinical Interview for the DSM-IV (SCID). The OCD and SOD patients met the DSM-IV criteria for OCD and schizophrenia commodity of OCD, respectively. Exclusionary criteria included any other major psychiatric disorder (e.g., major depressive disorder,
Demographic and clinical variables
Basic demographic and clinical characteristics of OCD-GI, OCD-PI, SOD-GI and SOD-PI groups were summarized in Table 1. Significant differences were only found among the four patients' group in the treatment status, relative verbal IQ, YBOCS score (total, obsessive and compulsive subscales), BABS score, DEX score, verbal memory-delay, visual memory-immediate and delay, working memory-total and attention (p < 0.05). Significant difference in scores of SAI-E (p < 0.05) was found between SOD-GI and
Discussion
In the present study, we compared the clinical characteristics, neurocognitive domains, and neuroimaging parameters among OCD-GI, OCD-PI, SOD-GI and SOD-PI. The detailed discussion is as following.
As the core clinical symptoms of both SOD and OCD, scores of YBOCS are affected by the main effect of diagnosis, while they are also closely related to the levels of insight, particularly insight into obsessive-compulsive symptoms. Although there is no significant difference of PANSS-A or PANSS-P
CRediT authorship contribution statement
X.Z.Z. and C.L.T. designed the research; J.G., W.T.L., J.F., performed the research; J.G. analyzed data and wrote the paper; J.Y.Y. participated in the revision and polishing of the article. All authors reviewed the paper.
Role of funding source
Funding for this study was provided by the National Natural Science Foundation of China, Grant 81671341.
Conflict of Interest
The authors declare no competing financial interest.
Acknowledgements
The data that support the findings of the study are available on request from the corresponding author. The data are not publicly available due to privacy and ethical issues of clinical data.
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