Neurobiology of insight deficits in schizophrenia: An fMRI study

Investigating the association between symptoms and functional activity in brain regions in schizophrenia: A cross-sectional fmri-based neuroimaging study

Schizophrenia is a persistent neurological disorder profoundly affecting cognitive, emotional, and behavioral functions, prominently characterized by delusions, hallucinations, disordered speech, and abnormal motor activity. These symptoms often present diagnostic challenges due to their overlap with other forms of psychosis. Therefore, the implementation of automated diagnostic methodologies is imperative. This research leverages Functional Magnetic Resonance Imaging (fMRI), a neuroimaging modality capable of delineating functional activations across diverse brain regions. Furthermore, the utilization of evolving machine learning techniques for fMRI data analysis has significantly progressive. Here, our study stands as a novel attempt, focusing on the comprehensive assessment of both classical and atypical symptoms of schizophrenia. We aim to uncover associated changes in brain functional activity. Our study encompasses two distinct fMRI datasets (1.5T and 3T), each comprising 34 schizophrenia patients for the 1.5T dataset and 25 schizophrenia patients for the 3T dataset, along with an equal number of healthy controls. Machine learning algorithms are applied to assess data subsets, enabling an in-depth evaluation of the current functional condition concerning symptom impact. The identified voxels contribute to determining the brain regions most influenced by each symptom, as quantified by symptom intensity. This rigorous approach has yielded various new findings while maintaining an impressive classification accuracy rate of 97 %. By elucidating variations in activation patterns across multiple brain regions in individuals with schizophrenia, this study contributes to the understanding of functional brain changes associated with the disorder. The insights gained may inform differential clinical interventions and provide a means of assessing symptom severity accurately, offering new avenues for the management of schizophrenia.

Psychometric evaluation of the Arabic language version of the Birchwood Insight Scale in patients with schizophrenia

BACKGROUND

Clinical insight (i.e., impaired insight into illness) is increasingly recognized by the scientific community as a significant contributor to an array of psychological and clinical outcomes in schizophrenia. Therefore, its assessment using a reliable, rapid, easy and economic tool is important for clinical practice. This study proposes to investigate the psychometric properties of an Arabic translation of the Birchwood Insight Scale (BIS) in Arabic-speaking chronic patients with schizophrenia. Our objectives were to identify the most adequate factor structure of the BIS among the several measurement models previously proposed in the literature, verify the reliability and measurement invariance of the BIS across sex groups, and explore the concurrent validity of the BIS through examining its patterns of correlations with psychotic symptoms.

METHOD

One hundred seventeen Arabic-speaking chronic, remitted patients with schizophrenia took part in this study. An Arabic translated version of the BIS and the Positive and Negative Syndrome Scale (PANSS) were administered to participants.

RESULTS

Confirmatory factor analyses (CFA) showed that, after omitting two items with low loadings (items 1 and 2), the unidimensional factor model of the BIS showed good fit indices and a reliability of α = 0.68 and ω = 0.68. However, analyses failed to show good fit for the full-length one-, two-, and three-factor models of the BIS in its Arabic version. Measurement invariance of the Arabic 6-item one-factor BIS was established between males and females at the configural, metric and scalar levels; no statistically significant difference between males and females was found in terms of BIS scores. Finally, BIS scores correlated significantly with the PANSS scores in our sample, thus demonstrating adequate concurrent validity.

CONCLUSION

This study offers valuable additional psychometric information about the BIS based on results of CFA and other analyses in schizophrenia from a non-Western cultural environment. We believe that making the BIS available in Arabic might benefit clinicians working with Arabic-speaking patients with schizophrenia, open new avenues of research and gain a better knowledge into the nature of clinical insight and its relevance to psychopathology.

Cortical thinning in relation to impaired insight into illness in patients with treatment resistant schizophrenia

Impaired insight into illness is a common element of schizophrenia that contributes to treatment nonadherence and negative clinical outcomes. Previous studies suggest that impaired insight may arise from brain abnormalities. However, interpretations of these findings are limited due to small sample sizes and inclusion of patients with a narrow range of illness severity and insight deficits. In a large sample of patients with schizophrenia, the majority of which were designated as treatment-resistant, we investigated the associations between impaired insight and cortical thickness and subcortical volumes. A total of 94 adult participants with a schizophrenia spectrum disorder were included. Fifty-six patients (60%) had treatment-resistant schizophrenia. The core domains of insight were assessed with the VAGUS insight into psychosis scale. We obtained 3T MRI T1-weighted images, which were analysed using CIVET and MAGeT-Brain. Whole-brain vertex-wise analyses revealed impaired insight, as measured by VAGUS average scores, was related to cortical thinning in left frontotemporoparietal regions. The same analysis in treatment-resistant patients showed thinning in the same regions, even after controlling for age, sex, illness severity, and chlorpromazine antipsychotic dose equivalents. No association was found in non-treatment-resistant patients. Region-of-interest analyses revealed impaired general illness awareness was associated with cortical thinning in the left supramarginal gyrus when controlling for covariates. Reduced right and left thalamic volumes were associated with VAGUS symptom attribution and awareness of negative consequences subscale scores, respectively, but not after correction for multiple testing. Our results suggest impaired insight into illness is related to cortical thinning in left frontotemporoparietal regions in patients with schizophrenia, particularly those with treatment resistance where insight deficits may be more chronic.

Decreased insight, but not self-stigma or belief about medicine, is associated with greater severity of delusions in a sample of long-stay patients with schizophrenia: a cross-sectional study

BACKGROUND

There are, to date, limited and inconsistent findings concerning the relationship between insight and psychotic symptoms, despite some evidence in favor of the clinical and therapeutic relevance of the insight construct. We aimed to add to the pool of the available data in this area, by examining the correlations between the severity of insight and positive psychotic symptoms (delusions and auditory hallucinations), while accounting for self-stigma and attitudes towards medication, in a sample of long-stay inpatients with schizophrenia.

METHODS

A cross-sectional study was conducted at the Psychiatric Hospital of the Cross, between July and October 2021. A total of 82 patients diagnosed with schizophrenia (aged 55.55 ± 10.21 years, 54.9% males) were enrolled. The semi-structured psychotic symptom rating scales, the Birchwood Insight Scale, the Belief About Medicine Questionnaire, and the Internalized Stigma of Mental Illness were used.

RESULTS

The mean duration of illness in years was 30.15 ± 11.73, and the mean duration of hospitalization in years was 17.56 ± 9.24. Sixteen out of the 82 patients (19.5%) were considered as having poor insight. Bivariate analyses showed that higher chlorpromazine equivalent dose was significantly associated with more delusions, whereas higher insight was significantly associated with lower delusions. Multivariable analyses revealed that Higher chlorpromazine equivalent dose (Beta = 0.004) was significantly associated with more delusions, whereas higher insight (Beta = - 0.89) was significantly associated with less delusions. No significant associations were found between insight, self-stigma and hallucinations.

CONCLUSION

Our results imply that more impaired insight is associated with greater severity of delusions, above and beyond the effects of self-stigma and medication doses. These findings are valuable to aid clinicians and researchers improve their understanding of the relationship insight-psychotic symptoms, and could help personalize prevention and early intervention strategies in schizophrenia.

Where the public health principles meet the individual: a framework for the ethics of compulsory outpatient treatment in psychiatry

Background

Compulsory treatments represent a legal means of imposing treatment on an individual, usually with a mental illness, who refuses therapeutic intervention and poses a risk of self-harm or harm to others. Compulsory outpatient treatment (COT) in psychiatry, also known as community treatment order, is a modality of involuntary treatment that broadens the therapeutic imposition beyond hospitalization and into the community. Despite its existence in over 75 jurisdictions worldwide, COT is currently one of the most controversial topics in psychiatry, and it presents significant ethical challenges. Nonetheless, the ethical debate regarding compulsory treatment almost always stops at a preclinical level, with the different ethical positions arguing for or against its use, and there is little guidance to support for the individual clinicians to act ethically when making the decision to implement COT.

Main body

The current body of evidence is not clear about the efficacy of COT. Therefore, despite its application in several countries, evidence favouring the use of COT is controversial and mixed at best. In these unclear circumstances, ethical guidance becomes paramount. This paper provides an ethical analysis of use of COT, considering the principlist framework established by Ross Upshur in 2002 to justify public health interventions during the 2002–2004 severe acute respiratory syndrome outbreak. This paper thoroughly examines the pertinence of using the principles of harm, proportionality, reciprocity, and transparency when considering the initiation of COT.

Conclusion

Ross Upshur’s principlist model provides a useful reflection tool for justifying the application of COT. This framework may help to inform sounder ethical decisions in clinical psychiatric practice.

Efficacy of Transcranial Direct Current Stimulation to Improve Insight in Patients With Schizophrenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND AND HYPOTHESIS

Impaired insight into the illness and its consequences is associated with poor outcomes in schizophrenia. While transcranial direct current stimulation (tDCS) may represent a potentially effective treatment strategy to relieve various symptoms of schizophrenia, its impact on insight remains unclear. To investigate whether tDCS would modulate insight in patients with schizophrenia, we undertook a meta-analysis based on results from previous RCTs that investigated the clinical efficacy of tDCS. We hypothesize that repeated sessions of tDCS will be associated with insight improvement among patients.

STUDY DESIGN

PubMed and ScienceDirect databases were systematically searched to identify RCTs that delivered at least 10 tDCS sessions in patients with schizophrenia. The primary outcome was the change in insight score, assessed by the Positive and Negative Syndrome Scale (PANSS) item G12 following active tDCS sessions as opposed to sham stimulation. Effect sizes were calculated for all studies and pooled using a random-effects model. Meta-regression and subgroup analyses were conducted.

STUDY RESULTS

Thirteen studies (587 patients with schizophrenia) were included. A significant pooled effect size (g) of -0.46 (95% CI [-0.78; -0.14]) in favor of active tDCS was observed. Age and G12 score at baseline were identified as significant moderators, while change in total PANSS score was not significant.

CONCLUSIONS

Ten sessions of active tDCS with either frontotemporoparietal or bifrontal montage may improve insight into the illness in patients with schizophrenia. The effect of this treatment could contribute to the beneficial outcomes observed in patients following stimulation.

Altered working memory-related brain activity in children at familial high risk for psychosis: A preliminary study

BACKGROUND

Schizophrenia spectrum disorders are heritable illnesses that usually manifest in early adulthood but are increasingly viewed as neurodevelopmental disorders. Functional magnetic resonance imaging (fMRI) studies show altered brain activity during performance of working memory (WM) tasks in both individuals with schizophrenia and their first-degree relatives as compared to healthy controls (HC). This study examined whether similar changes are already present in pre-adolescent children at familial high-risk (FHR) for psychosis.

METHODS

37 children (17 FHR, 20 HC) between 7 and 12 years old participated in this study. WM performance was assessed using the Wechsler Intelligence Scale for Children-IV (WISC-IV). To assess brain activation during WM performance, participants completed a visual block-designed n-back task with 2 conditions (2-back and 0-back) during scanning. fMRI data was preprocessed and analyzed using FSL Feat.

RESULTS

Compared to HC, FHR children showed significantly lower WISC-IV WM scores. In addition, FHR children exhibited hypoactivation in the 2-back (versus 0-back) condition in a cluster encompassing bilateral precuneus and cuneus and right posterior cingulate cortex. There were no significant group-differences in n-back task performance and brain activation. The precuneus cluster was not correlated with n-back performance or WISC WM scores.

CONCLUSIONS

The current results provide preliminary evidence of impaired WM function and altered brain activity during WM performance in children with a familial predisposition for psychosis. Longitudinal studies are needed to determine whether these findings are related to abnormal brain development and predictive of cognitive deficits and psychosis later in life.

Delineating insight-processing-related functional activations in the precuneus in first-episode psychosis patients

Poor insight is a central characteristic of psychotic disorders, and it has been suggested to result from a general dysfunction in self-reflection. However, brain processing of clinical insight and more general self-reflection has not been directly compared. We compared tasks on (1) self-reflection on psychosis-related mental functioning (clinical insight, in patients only), (2) self-reflection on mental functioning unrelated to psychosis (general metacognition), and (3) semantic control during blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging with 19 first-episode psychosis patients and 24 control participants. Arterial-spin-labeling (ASL) images were collected at rest. Clinical insight was evaluated with the Schedule for the Assessment of Insight. In patients, posterosuperior precuneus showed stronger activation during the insight task than during the semantic control task, while anteroinferior precuneus and posterior cingulate cortex (PCC) showed stronger activation during the insight task than during the general metacognition task. No significant group differences in brain activation emerged during the general metacognition task. Although the BOLD measures did not correlate with clinical insight measures, ASL-measured cerebral blood flow (CBF) values did correlate when extracted from the task-selective precuneus/PCC areas: higher CBF correlated with higher clinical insight scores. These results suggest that regions in the posteromedial cortex are selective for clinical insight.

Effects of visual attention modulation on dynamic functional connectivity during own-face viewing in body dysmorphic disorder

Body dysmorphic disorder (BDD) is characterized by preoccupations with misperceptions of one's physical appearance. Previous neuroimaging studies in BDD have yet to examine dynamic functional connectivity (FC) patterns between brain areas, necessary to capture changes in activity in response to stimuli and task conditions. We used Leading Eigenvector Dynamics Analysis to examine whole-brain dynamic FC from fMRI data during an own-face viewing task in 29 unmedicated adults with BDD with facial concerns and 30 healthy controls. The task involved two parts: (1) unconstrained, naturalistic viewing and (2) holding visual attention in the center of the image, to reduce scanning and fixation on perceived facial flaws. An FC state consisting of bilateral medial orbitofrontal cortex regions occurred significantly less often during the visual attention condition and afterward during the unconstrained face viewing in BDD participants, compared to the first unconstrained face viewing, a pattern that differed from controls. Moreover, the probability of this state during the second unconstrained face viewing was associated with severity of obsessions and compulsions and degree of poor insight in BDD, suggesting its clinical significance. These findings have implications for understanding the pathophysiology of own-face viewing in BDD and how it is affected by modification of viewing patterns, which may have implications for novel perceptual retraining treatment designs.

Insight does not come at random: Individual gray matter networks relate to clinical and cognitive insight in schizophrenia

BACKGROUND

Impaired clinical and cognitive insight are prevalent in schizophrenia and relate to poorer outcome. Good insight has been suggested to depend on social cognitive and metacognitive abilities requiring global integration of brain signals. Impaired insight has been related to numerous focal gray matter (GM) abnormalities distributed across the brain suggesting dysconnectivity at the global level. In this study, we test whether global integration deficiencies reflected in gray matter network connectivity underlie individual variations in insight.

METHODS

We used graph theory to examine whether individual GM-network metrics relate to insight in patients with a psychotic disorder (n = 114). Clinical insight was measured with the Schedule for the Assessment of Insight-Expanded and item G12 of the Positive and Negative Syndrome Scale, and cognitive insight with the Beck Cognitive Insight Scale. Individual GM-similarity networks were created from GM-segmentations of T1-weighted MRI-scans. Graph metrics were calculated using the Brain Connectivity Toolbox.

RESULTS

Networks of schizophrenia patients with poorer clinical insight showed less segregation (i.e. clustering coefficient) into specialized subnetworks at the global level. Schizophrenia patients with poorer cognitive insight showed both less segregation and higher connectedness (i.e. lower path length) of their brain networks, making their network topology more "random".

CONCLUSIONS

Our findings suggest less segregated processing of information in patients with poorer cognitive and clinical insight, in addition to higher connectedness in patients with poorer cognitive insight. The ability to take a critical perspective on one's symptoms (clinical insight) or views (cognitive insight) might depend especially on segregated specialized processing within distinct subnetworks.

Adjunct high-frequency transcranial random noise stimulation over the lateral prefrontal cortex improves negative symptoms of schizophrenia: A randomized, double-blind, sham-controlled pilot study

High-frequency transcranial random noise stimulation (hf-tRNS) is a non-invasive neuromodulatory technique capable of increasing human cortex excitability. There were only published case reports on the use of hf-tRNS targeting the lateral prefrontal cortex in treating negative symptoms of schizophrenia, thus necessitating systematic investigation. We designed a randomized, double-blind, sham-controlled trial in a cohort of stabilized schizophrenia patients to examine the efficacy of add-on hf-tRNS (100-640 Hz; 2 mA; 20 min) using a high definition 4 × 1 electrode montage (anode AF3, cathodes AF4, F2, F6, and FC4) in treating negative symptoms (ClinicalTrials.gov ID: NCT04038788). Participants received either active hf-tRNS or sham twice daily for 5 consecutive weekdays. Primary outcome measure was the change over time in the Positive and Negative Syndrome Scale Factor Score for Negative Symptoms (PANSS-FSNS), which was measured at baseline, after 10-session stimulation, and at one-week and one-month follow-ups. Among 36 randomized patients, 35 (97.2%) completed the trial. Intention-to-treat analysis showed a significantly greater decrease in PANSS-FSNS score after active (-17.11%) than after sham stimulation (-1.68%), with a large effect size (Cohen's d = 2.16, p < 0.001). The beneficial effect lasted for up to one month. In secondary-outcome analyses, the authors observed improvements with hf-tRNS of disorganization symptoms, unawareness of negative symptoms, subjective response to taking antipsychotics, and antipsychotic-induced extrapyramidal symptoms. No effects were observed on the neurocognitive performance and other outcome measures. Overall, hf-tRNS was safe and efficacious in improving negative symptoms. Our promising findings should be confirmed in a larger sample of patients with predominant negative symptoms.

Association Between ZNF804A Gene rs1344706 Polymorphism and Brain Functions in Healthy Individuals: A Systematic Review and Voxel-Based Meta-Analysis

OBJECTIVE

Zinc finger protein 804A (ZNF804A) protein participates in embryonic neural repair and development. The single nucleotide polymorphism rs1344706 in ZNF804A gene is closely related to functional abnormalities of the human brain. However, these results are inconsistent. This association was verified by meta-analysis in this study.

METHODS

Fifteen studies on functional magnetic resonance imaging involving 1710 healthy individuals were included in the systematic review and meta-analysis used by Anisotropic Effect-Size Signed Differential Mapping software.

RESULTS

Functional connectivity of the right dorsolateral prefrontal cortex (rDLPFC)-left hippocampus in the rs1344706 risk allele carrier was significantly increased (z = 2.066, p < 0.001), while those in the rDLPFC-left middle frontal gyrus (z = -1.420, p < 0.001) and rDLPFC-right middle frontal gyrus (z = -1.298, p < 0.001) were significantly decreased. Neural activity of the left anterior cingulate gyrus in the rs1344706 risk allele carrier was significantly decreased (z = -2.525, p < 0.001). Sensitivity analysis was almost stable, and no publication bias was found.

CONCLUSION

The changes in brain function have a clear correlation with ZNF804A gene in healthy individuals, which indicate the contribution of genetic variants on brain dysfunction.

REGISTRATION NUMBER

This meta-analysis is registered in PROSPERO (No. CRD42016051331).

Association Between Lack of Insight and Prefrontal Serotonin Transporter Availability in Antipsychotic-Free Patients with Schizophrenia: A High-Resolution PET Study with [11C]DASB

BACKGROUND

Previous studies suggested a link between serotonergic neurotransmission and impaired insight in schizophrenia. In this study, we examined the relationship between serotonin transporter (SERT) availability in regions of the prefrontal cortex (dorsolateral, ventrolateral, ventromedial, and orbitofrontal cortices) and insight deficits in antipsychotic-free patients with schizophrenia using high-resolution positron emission tomography (PET) with [¹¹C]DASB.

METHODS

Nineteen patients underwent [¹¹C]DASB PET and 7-Tesla magnetic resonance imaging scans. To assess SERT availability, the binding potential with respect to non-displaceable compartment (BP_ND) was derived using the simplified reference tissue model. Patients' level of insight was assessed using the Insight and Treatment Attitude Questionnaire (ITAQ). The relationship between ITAQ scores and [¹¹C]DASB BP_ND values was examined using the region-of-interest (ROI)- and voxel-based analyses with relevant variables as covariates. The prefrontal cortex and its four subregions were selected as a priori ROIs since the prefrontal cortex has been implicated as the critical neuroanatomical substrate of impaired insight in schizophrenia.

RESULTS

The ROI-based analysis revealed that the ITAQ illness insight dimension had significant negative correlations with the [¹¹C]DASB BP_ND in the left dorsolateral, left orbitofrontal, and bilateral ventrolateral prefrontal cortices. The ITAQ treatment insight dimension had significant negative correlations with the [¹¹C]DASB BP_ND in the bilateral dorsolateral, left orbitofrontal, and bilateral ventrolateral prefrontal cortices. The ITAQ total score showed significant negative correlations with the [¹¹C]DASB BP_ND in the bilateral prefrontal cortex and three subregions (dorsolateral, ventrolateral, and orbitofrontal cortices). A supplementary voxel-based analysis corroborated a significant negative association between the ITAQ score and the [¹¹C]DASB BP_ND in the prefrontal cortices.

CONCLUSION

Our study provides in vivo evidence of significant negative correlations between insight deficits and prefrontal SERT availability in patients with schizophrenia, suggesting significant involvement of prefrontal serotonergic signaling in impaired insight, one of the core symptoms of schizophrenia.

[Research on brain network for schizophrenia classification based on resting-state functional magnetic resonance imaging]

How to extract high discriminative features that help classification from complex resting-state fMRI (rs-fMRI) data is the key to improving the accuracy of brain disease recognition such as schizophrenia. In this work, we use a weighted sparse model for brain network construction, and utilize the Kendall correlation coefficient (KCC) to extract the discriminative connectivity features for schizophrenia classification, which is conducted with the linear support vector machine. Experimental results based on the rs-fMRI of 57 schizophrenia patients and 64 healthy controls show that our proposed method is more effective ( i.e., achieving a significantly higher classification accuracy, 81.82%) than other competing methods. Specifically, compared with the traditional network construction methods (Pearson's correlation and sparse representation) and the commonly used feature selection methods (two-sample t-test and Least absolute shrinkage and selection operator (Lasso)), the algorithm proposed in this paper can more effectively extract the discriminative connectivity features between the schizophrenia patients and the healthy controls, and further improve the classification accuracy. At the same time, the discriminative connectivity features extracted in the work could be used as the potential clinical biomarkers to assist the identification of schizophrenia.

Brain areas associated with clinical and cognitive insight in psychotic disorders: A systematic review and meta-analysis

In the past years, ample interest in brain abnormalities related to clinical and cognitive insight in psychosis has contributed several neuroimaging studies to the literature. In the current study, published findings on the neural substrates of clinical and cognitive insight in psychosis are integrated by performing a systematic review and meta-analysis. Coordinate-based meta-analyses were performed with the parametric coordinate-based meta-analysis approach, non-coordinate based meta-analyses were conducted with the metafor package in R. Papers that could not be included in the meta-analyses were systematically reviewed. Thirty-seven studies were retrieved, of which 21 studies were included in meta-analyses. Poorer clinical insight was related to smaller whole brain gray and white matter volume and gray matter volume of the frontal gyri. Cognitive insight was predominantly positively associated with structure and function of the hippocampus and ventrolateral prefrontal cortex. Impaired clinical insight is not associated with abnormalities of isolated brain regions, but with spatially diffuse global and frontal abnormalities suggesting it might rely on a range of cognitive and self-evaluative processes. Cognitive insight is associated with specific areas and appears to rely more on retrieving and integrating self-related information.

Insight in psychosis: A critical review of the contemporary confusion

This commentary highlights the context, complexity, conflicting claims and the contemporary confusion related to insight in people with psychosis. Traditional psychiatric precepts suggests that good insight is inversely related to the severity of psychotic symptoms and directly related to depression scores, better clinical outcome, and treatment adherence. However, recent studies have recognised that insight does not predict outcomes, changes over time, and is dependent on the trajectory of the individual's illness and the social and cultural context arguing that "insight" is an explanatory model and a coping strategy. Methodological issues related to the assessment of insight, the limitations of psychiatric classification and complex interaction between biology and the environment make simplistic explanations of the concept of insight less than useful. The paper argues that the biomedical model should be presented without dismissing or devaluing patient beliefs and explanations. Psychiatry needs to embrace the complexity of mental illness and value diverse attempts at restoring homeostasis.

Neural correlates of altered insight in frontotemporal dementia: a systematic review

Altered insight into disease or specific symptoms is a prominent clinical feature of frontotemporal dementia (FTD). Understanding the neural bases of insight is crucial to help improve FTD diagnosis, classification and management. A systematic review to explore the neural correlates of altered insight in FTD and associated syndromes was conducted. Insight was fractionated to examine whether altered insight into different neuropsychological/behavioural objects is underpinned by different or compatible neural correlates. 6 databases (Medline, Embase, PsycINFO, Web of Science, BIOSIS and ProQuest Dissertations & Theses Global) were interrogated between 1980 and August 2019. 15 relevant papers were found out of 660 titles screened. The studies included suggest that different objects of altered insight are associated with distinctive brain areas in FTD. For example, disease unawareness appears to predominantly correlate with right frontal involvement. In contrast, altered insight into social cognition potentially involves, in addition to frontal areas, the temporal gyrus, insula, parahippocampus and amygdala. Impaired insight into memory problems appears to be related to the frontal lobes, postcentral gyrus, parietal cortex and posterior cingulate. These results reflect to a certain extent those observed in other neurodegenerative conditions like Alzheimer's disease (AD) and also other brain disorders. Nevertheless, they should be cautiously interpreted due to variability in the methodological aspects used to reach those conclusions. Future work should triangulate different insight assessment approaches and brain imaging techniques to increase the understanding of this highly relevant clinical phenomenon in dementia.

Positive and general psychopathology associated with specific gray matter reductions in inferior temporal regions in patients with schizophrenia

Schizophrenia is a complex disorder that affects perception, cognition, and emotion causing symptoms such as delusions, hallucinations, and suspiciousness. Schizophrenia is also associated with structural cortical abnormalities including lower gray matter (GM) concentration, GM volume, and cortical thickness relative to healthy control individuals. However, the association between GM measures and symptom dimensions in schizophrenia is still not well understood. Here, we applied parallel independent component analysis (pICA), a higher-order statistical approach that identifies covarying patterns within two (or more) data modalities simultaneously, to link covarying brain networks of GM concentration with covarying linear combinations of the positive and negative syndrome scale (PANSS). In a large sample of patients with schizophrenia (n = 337) the association between these two data modalities was investigated. The pICA revealed a distinct PANSS profile characterized by increased delusional symptoms, suspiciousness, hallucinations, and anxiety, that was associated with a pattern of lower GM concentration in inferior temporal gyri and fusiform gyri and higher GM concentration in the sensorimotor cortex. GM alterations replicate previous findings; additionally, applying a multivariate technique, we were able to map a very specific symptom profile onto these GM alterations extending our understanding of cortical abnormalities associated with schizophrenia. Techniques like parallel ICA can reveal linked patterns of alterations across different data modalities that can help to identify biologically-informed phenotypes which might help to improve future treatment targets.

Cognitive capacity similarly predicts insight into symptoms in first- and multiple-episode psychosis

BACKGROUND

Lack of insight is a frequent characteristic of psychotic disorders, both in patients who recently experienced a first episode of psychosis (FEP) and those who experience recurrent multiple episodes (MEP). Insight is a multifaceted construct: its clinical form notably includes the unawareness of being ill, of symptoms, and of the need for treatment. Cognitive capacity is among the key determinants of insight into symptoms, but less is known about whether stage of illness (FEP vs. MEP) moderates this association.

METHODS

Our aim is to evaluate the association between cognitive capacity and symptom unawareness using structural equation modeling and moderated multiple regression. A total of 193 FEP and MEP patients were assessed using the CogState battery and the Scale to Assess Unawareness of Mental Disorder.

RESULTS

Analyses suggest that cognitive capacity accounts for a relatively small proportion of the total variation in symptom unawareness (6.4%). There was no evidence to suggest a moderating effect of stage of illness on this association.

CONCLUSIONS

The effect of general cognitive capacity on symptom unawareness is relatively small, and this basic relation was unrelated to stage of illness. It is possible that stage of illness could moderate this association only for certain facets of insight not assessed in this study (e.g., unawareness of the need for treatment).

Pleiotropic action of genetic variation in ZNF804A on brain structure: a meta-analysis of magnetic resonance imaging studies

OBJECTIVE

The zinc finger protein 804A (ZNF804A) gene encodes the protein 804A containing the C2H2 zinc finger structure, which plays an important role in embryonic nerve development and repair. Previous studies have shown a significant association between the ZNF804A genetic variation polymorphism rs1344706 and the risk of schizophrenia and brain structure abnormalities. However, the findings are inconsistent.

MATERIALS AND METHODS

Seventeen studies on structural magnetic resonance imaging (sMRI), with 1,031 schizophrenia patients and 3,416 healthy controls, were included in the meta-analysis. These analyses were performed using Anisotropic Effect-Size Signed Differential Mapping (AES-SDM) software and Comprehensive Meta-Analysis (CMA) software.

RESULTS

rs1344706 risk allele carriers of schizophrenia had increased gray matter in the brain regions including frontal lobe, temporal lobe, and other brain regions, but the carriers of healthy individuals had decreased gray matter and white matter integrity in the frontal lobe, central network, and other brain regions. The results of sensitivity analysis are stable, but publication bias exists in a few analyses of indexes.

CONCLUSION

Abnormalities of brain structure have a strong relationship with ZNF804A gene rs1344706 polymorphism, but the association may be different in healthy individuals and those with mental disorders.

Insight and emotion regulation in schizophrenia: A brain activation and functional connectivity study

Background

Insight is impaired in the majority of schizophrenia patients. The exact neural correlates of impaired insight remain unclear. We assume that the ability to regulate emotions contributes to having good clinical insight, as patients should be able to regulate their emotional state in such a way that they can adapt adequately in order to cope with impaired functioning and negative stigma associated with a diagnosis of schizophrenia. Numerous studies have shown emotional dysregulation in schizophrenia. We investigated the association between insight and brain activation and connectivity during emotion regulation.

Methods

Brain activation during emotion regulation was measured with functional MRI in 30 individuals with schizophrenia. Two emotion regulation strategies were examined: cognitive reappraisal and expressive suppression. Clinical insight was measured with the Schedule for the Assessment of Insight – Expanded, and cognitive insight was measured with the Beck Cognitive Insight Scale. Whole brain random effects multiple regression analyses were conducted to assess the relation between brain activation during emotion regulation and insight. Generalized psychophysiological interaction (gPPI) was used to investigate the relation between task-related connectivity and insight.

Results

No significant associations were found between insight and neural correlates of cognitive reappraisal. For clinical insight and suppression, significant positive associations were found between symptom relabeling and activation in the left striatum, thalamus and insula, right insula and caudate, right pre- and postcentral gyrus, left superior occipital gyrus and cuneus and right middle and superior occipital gyrus and cuneus. Furthermore, reduced clinical insight was associated with more connectivity between midline medial frontal gyrus and right middle occipital gyrus. For cognitive insight and suppression, significant positive associations were found between self-reflectiveness and activation in pre- and postcentral gyrus and left middle cingulate gyrus.

Conclusions

Our results suggest an association between the capacity to relabel symptoms and activation of brain systems involved in cognitive-emotional control and visual processing of negative stimuli. Furthermore, poorer self-reflectiveness may be associated with brain systems subserving control and execution.

•

We examined the association between emotion regulation and insight in schizophrenia.

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Patients with poorer insight engage different neural pathways during suppression.

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This finding was strengthened by connectivity measures of corresponding brain areas.

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No relationship between cognitive reappraisal and insight was found.

The Effects of Add-on Fronto-Temporal Transcranial Direct Current Stimulation (tDCS) on Auditory Verbal Hallucinations, Other Psychopathological Symptoms, and Insight in Schizophrenia: A Randomized, Double-Blind, Sham-Controlled Trial

BACKGROUND

The efficacy of fronto-temporal transcranial direct current stimulation in treating auditory verbal hallucinations and other psychopathological symptoms of schizophrenia patients has been examined in a small number of clinical trials with limited sample sizes, but the results are mixed. Fronto-temporal transcranial direct current stimulation has also been demonstrated to enhance patients' insight into their mental illness in an open-label pilot study. The current investigation aimed to investigate the therapeutic effects of fronto-temporal transcranial direct current stimulation on the severity of auditory verbal hallucinations, other schizophrenia symptoms, and insight in a large double blind, randomized, sham-controlled trial.

METHODS

Sixty patients with medication-refractory auditory verbal hallucinations were randomized over 2 conditions: transcranial direct current stimulation with 2-mA, twice-daily sessions for 5 consecutive days, with anodal stimulation to the left prefrontal cortex and cathodal stimulation to the left temporo-parietal junction, and sham treatment.

RESULTS

Fronto-temporal transcranial direct current stimulation failed to cause significant changes in the severity of auditory verbal hallucinations and other schizophrenia symptoms. The levels of insight into illness (effect size=0.511, P<.001) and positive symptoms (effect size=0.781, P<.001) were largely promoted by 5 days of transcranial direct current stimulation relative to sham treatment. The beneficial effects on the 2 insight dimensions remained 1 month after transcranial direct current stimulation.

CONCLUSIONS

Fronto-temporal transcranial direct current stimulation is not more effective for auditory verbal hallucinations and other schizophrenia symptoms than sham treatment. But the results of transcranial direct current stimulation-associated improvement in awareness of illness and positive symptoms show promise and provide a new direction for future research into insight promotion interventions in schizophrenia.

Symptom attribution and frontal cortical thickness in first-episode schizophrenia

AIM

Misattribution of symptoms is a common feature of schizophrenia, and likely involves impairment of metacognitive function that may be mediated by the frontal cortex. We aimed to compare frontal cortical thickness in first-episode schizophrenia (FES) patients with matched controls, and investigate its relationship with the symptom attribution dimension of insight in FES patients.

METHODS

We examined frontal cortical thickness in 92 minimally treated FES patients at baseline presentation and 93 healthy controls aged 16-45 years. We examined for correlations between symptom attribution as determined by the Birchwood Insight Scale (BIS) symptom relabeling subscale score and cortical thickness of frontal regions of interest (ROIs). We then examined for an association between symptom attribution and cortical thickness using multiple regression analysis.

RESULTS

FES patients exhibited significantly reduced cortical thicknesses for a number of frontal regions, namely the left medial orbitofrontal, left superior frontal, left frontal pole, right rostral middle frontal, right lateral orbitofrontal and right superior frontal regions. Reduced cortical thickness in FES patients was associated with symptom misattribution for the left and right rostral middle frontal, left caudal anterior cingulate, right superior frontal, and left and right pars triangularis regions. Reduced left rostral middle frontal thickness and left anterior cingulate thickness remained significant on regression analysis.

CONCLUSION

Our findings suggest that frontal neuroanatomical deficits that are present early in the disease process may be critical to the pathogenesis of symptom attribution in schizophrenia.

Genetic correlates of insight in schizophrenia

Insight in schizophrenia is clinically important as it is associated with several adverse outcomes. Genetic contributions to insight are unknown. We examined genetic contributions to insight by investigating if polygenic risk scores (PRS) and candidate regions were associated with insight.

METHOD

Schizophrenia case-only analysis of the Clinical Antipsychotics Trials of Intervention Effectiveness trial. Schizophrenia PRS was constructed using Psychiatric Genomics Consortium (PGC) leave-one out GWAS as discovery data set. For candidate regions, we selected 105 schizophrenia-associated autosomal loci and 11 schizophrenia-related oligodendrocyte genes. We used regressions to examine PRS associations and set-based testing for candidate analysis.

RESULTS

We examined data from 730 subjects. Best-fit PRS at p-threshold of 1e-07 was associated with total insight (R²=0.005, P=0.05, empirical P=0.054) and treatment insight (R²=0.005, P=0.048, empirical P=0.048). For models that controlled for neurocognition, PRS significantly predicted treatment insight but at higher p-thresholds (0.1 to 0.5) but did not survive correction. Patients with highest polygenic burden had 5.9 times increased risk for poor insight compared to patients with lowest burden. PRS explained 3.2% (P=0.002, empirical P=0.011) of variance in poor insight. Set-based analyses identified two variants associated with poor insight- rs320703, an intergenic variant (within-set P=6e-04, FDR P=0.046) and rs1479165 in SOX2-OT (within-set P=9e-04, FDR P=0.046).

CONCLUSION

To the best of our knowledge, this is the first study examining genetic basis of insight. We provide evidence for genetic contributions to impaired insight. Relevance of findings and necessity for replication are discussed.

Stronger default mode network connectivity is associated with poorer clinical insight in youth at ultra high-risk for psychotic disorders

Impaired clinical insight (CI) is a common symptom of psychotic disorders and a promising treatment target. However, to date, our understanding of how variability in CI is tied to underlying brain dysfunction in the clinical high-risk period is limited. Developing a stronger conception of this link will be a vital first step for efforts to determine if CI can serve as a useful prognostic indicator. The current study investigated whether variability in CI is related to major brain networks in adolescents and young adults at ultra high-risk (UHR) of developing psychosis. Thirty-five UHR youth were administered structured clinical interviews as well as an assessment for CI and underwent resting-state magnetic resonance imaging scans. Functional connectivity was calculated in the default mode network (DMN) and fronto-parietal network (FPN), two major networks that are dysfunctional in psychosis and are hypothesized to affect insight. Greater DMN connectivity between the posterior cingulate/precuneus and ventromedial prefrontal cortex (DMN) was related to poorer CI (R²=0.399). There were no significant relationships between insight and the FPN. This is the first study to relate a major brain network to clinical insight before the onset of psychosis. Findings are consistent with evidence if a hyperconnected DMN in schizophrenia and UHR, and similar to a previous study of insight and connectivity in schizophrenia. Results suggest that a strongly connected DMN may be related to poor self-awareness of subthreshold psychotic symptoms in UHR adolescents and young adults.

Unraveling interrelationships among psychopathology symptoms, cognitive domains and insight dimensions in chronic schizophrenia

INTRODUCTION

Insight in schizophrenia is long known to have a complex relationship with psychopathology symptoms and cognition. However, very few studies have examined models that explain these interrelationships.

METHODS

In a large sample derived from the NIMH Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) schizophrenia trial (N=1391), we interrogated these interrelationships for potential causal pathways using structural equation modeling. Using the NIMH consensus model, latent variables were constructed for psychopathology symptom dimensions, including positive, negative, disorganized, excited and depressed from the Positive and Negative Syndrome Scale (PANSS) items. Neurocognitive variables were created from five predefined domains of working memory, verbal memory, reasoning, vigilance and processing speed. Illness insight and treatment insight were tested using latent variables constructed from the Illness and Treatment Attitude Questionnaire (ITAQ).

RESULTS

Disorganized symptoms had the strongest effect on insight. Illness insight mediated the relationship of positive, depressed, and disorganized symptoms with treatment insight. Neurocognition mediated the relationship between disorganized and treatment insight and depressed symptoms and treatment insight. There was no effect of negative symptoms on either illness insight or treatment insight. Taken together, our results indicate overlapping and unique relational paths for illness and treatment insight dimensions, which could suggest differences in causal mechanisms and potential interventions to improve insight.

Insight in schizophrenia spectrum disorders: relationship with behavior, mood and perceived quality of life, underlying causes and emerging treatments

Poor insight in schizophrenia is prevalent across cultures and phases of illness. In this review, we examine the recent research on the relationship of insight with behavior, mood and perceived quality of life, on its complex roots, and on the effects of existing and emerging treatments. This research indicates that poor insight predicts poorer treatment adherence and therapeutic alliance, higher symptom severity and more impaired community function, while good insight predicts a higher frequency of depression and demoralization, especially when coupled with stigma and social disadvantage. This research also suggests that poor insight may arise in response to biological, experiential, neuropsychological, social-cognitive, metacognitive and socio-political factors. Studies of the effects of existing and developing treatments indicate that they may influence insight. In the context of earlier research and historical models, these findings support an integrative model of poor insight. This model suggests that insight requires the integration of information about changes in internal states, external circumstances, others' perspectives and life trajectory as well as the multifaceted consequences and causes of each of those changes. One implication is that treatments should, beyond providing education, seek to assist persons with schizophrenia to integrate the broad range of complex and potentially deeply painful experiences which are associated with mental illness into their own personally meaningful, coherent and adaptive picture.

Insight in psychosis: Standards, science, ethics and value judgment

BACKGROUND

The clinical assessment of insight solely employs biomedical perspectives and criteria to the complete exclusion of context and culture and to the disregard of values and value judgments.

AIM

The aim of this discussion article is to examine recent research from India on insight and explanatory models in psychosis and re-examine the framework of assessment, diagnosis and management of insight and explanatory models.

METHODS

Recent research from India on insight in psychosis and explanatory models is reviewed.

RESULTS

Recent research, which has used longitudinal data and adjusted for pretreatment variables, suggests that insight and explanatory models of illness at baseline do not predict course, outcome and treatment response in schizophrenia, which seem to be dependent on the severity and quality of the psychosis. It supports the view that people with psychosis simultaneously hold multiple and contradictory explanatory models of illness, which change over time and with the trajectory of the illness. It suggests that insight, like all explanatory models, is a narrative of the person's reality and a coping strategy to handle with the varied impact of the illness.

CONCLUSION

This article argues that the assessment of insight necessarily involves value entailments, commitments and consequences. It supports a need for a broad-based approach to assess awareness, attribution and action related to mental illness and to acknowledge the role of values and value judgment in the evaluation of insight in psychosis.

Neurobiological Basis of Insight in Schizophrenia: A Systematic Review

BACKGROUND

Insight in schizophrenia is defined as awareness into illness, symptoms, and need for treatment and has long been associated with cognition, other psychopathological symptoms, and several adverse clinical and functional outcomes. However, the biological basis of insight is not clearly understood.

OBJECTIVE

The aim of this systematic review was to critically evaluate and summarize advances in the study of the biological basis of insight in schizophrenia and to identify gaps in this knowledge.

METHODS

A literature search of PubMed, CINAHL, PsycINFO, and EMBASE databases was conducted using search terms to identify articles relevant to the biology of insight in schizophrenia published in the last 6 years. Articles that focused on etiology of insight in schizophrenia and those that examined the neurobiology of insight in schizophrenia or psychoses were chosen for analysis. Articles on insight in conditions other than schizophrenia or psychoses and which did not investigate the neurobiological underpinnings of insight were excluded from the review.

RESULTS

Twenty-six articles met the inclusion criteria for this review. Of the 26 articles, 3 focused on cellular abnormalities and 23 were neuroimaging studies. Preliminary data identify the prefrontal cortex, cingulate cortex, and regions of the temporal and parietal lobe (precuneus, inferior parietal lobule) and hippocampus as the neural correlates of insight.

DISCUSSION

A growing body of literature attests to the neurobiological basis of insight in schizophrenia. Current evidence supports the neurobiological basis of insight in schizophrenia and identifies specific neural correlates for insight types and its dimensions. Further studies that examine the precise biological mechanisms of insight are needed to apply this knowledge to effective clinical intervention development.

Insight and white matter fractional anisotropy in first-episode schizophrenia

Impaired insight is a hallmark feature of schizophrenia. Structural studies implicate predominantly prefrontal, cingulate, cuneus/precuneus, and inferior temporal brain regions. The cortical midline structures (CMS) are also implicated in functional studies primarily through self-reflective processing tasks. However, few studies have explored the relationship between white matter tracts and insight in schizophrenia, and none in first-episode schizophrenia (FES). Here, we examined for fractional anisotropy (FA) differences in 89 minimally treated FES patients and 98 matched controls, and identified those FA differences associated with impaired clinical insight in patients. We found widespread FA reduction in FES patients compared to controls. Poorer insight in patients was predicted by lower FA values in a number of white matter tracts with a predilection for tracts associated with cortical midline structures (fronto-occipital, cingulate, cingulate hippocampus, uncinate, anterior corona radiata), and more severe depressive symptoms. The association between FA abnormalities and insight was most robust for the awareness of symptoms and illness awareness domains. Our study implicates a network of tracts involved in impaired insight in schizophrenia with a predilection for the CMS. This study is a first step in delineating the white matter tracts involved in insight impairment in schizophrenia prior to chronicity.

Frontal lobe alterations in schizophrenia: a review

Abstract Objective: To highlight the changes in the frontal lobe of the human brain in people with schizophrenia. Methods: This was a qualitative review of the literature. Results: Many schizophrenic patients exhibit functional, structural, and metabolic abnormalities in the frontal lobe. Some patients have few or no alterations, while some have more functional and structural changes than others. Magnetic resonance imaging (MRI) shows structural and functional changes in volume, gray matter, white matter, and functional activity in the frontal lobe, but the mechanisms underlying these changes are not yet fully understood. Conclusion: When schizophrenia is studied as an essential topic in the field of neuropsychiatry, neuroscientists find that the frontal lobe is the most commonly involved area of the human brain. A clear picture of how this lobe is affected in schizophrenia is still lacking. We therefore recommend that further research be conducted to improve understanding of the pathophysiology of this psychiatric dilemma.

Voxel-based magnetic resonance imaging investigation of poor and preserved clinical insight in people with schizophrenia

AIM

To define regional grey-matter abnormalities in schizophrenia patients with poor insight (Insight^-), relative to patients with preserved clinical insight (Insight⁺), and healthy controls.

METHODS

Forty stable schizophrenia outpatients (20 Insight^- and 20 Insight⁺) and 20 healthy controls underwent whole brain magnetic resonance imaging (MRI). Insight in all patients was assessed using the Birchwood Insight Scale (BIS; a self-report measure). The two patient groups were pre-selected to match on most clinical and demographic parameters but, by design, they had markedly distinct BIS scores. Voxel-based morphometry employed in SPM8 was used to examine group differences in grey matter volumes across the whole brain.

RESULTS

The three participant groups were comparable in age [F(2,57) = 0.34, P = 0.71] and the patient groups did not differ in age at illness onset [t(38) = 0.87, P = 0.39]. Insight^- and Insight⁺ patient groups also did not differ in symptoms on the Positive and Negative Syndromes scale (PANSS): Positive symptoms [t(38) = 0.58, P = 0.57], negative symptoms [t(38) = 0.61, P = 0.55], general psychopathology [t(38) = 1.30, P = 0.20] and total PANSS scores [t(38) = 0.21, P = 0.84]. The two patient groups, as expected, varied significantly in the level of BIS-assessed insight [t(38) = 12.11, P < 0.001]. MRI results revealed lower fronto-temporal, parahippocampal, occipital and cerebellar grey matter volumes in Insight^- patients, relative to Insight⁺ patients and healthy controls (for all clusters, family-wise error corrected P < 0.05). Insight⁺ patient and healthy controls did not differ significantly (P > 0.20) from each other.

CONCLUSION

Our findings demonstrate a clear association between poor clinical insight and smaller fronto-temporal, occipital and cerebellar grey matter volumes in stable long-term schizophrenia patients.

The fragmented self: imbalance between intrinsic and extrinsic self-networks in psychotic disorders

Self-disturbances are among the core features of schizophrenia and related psychotic disorders. The basic structure of the self could depend on the balance between intrinsic and extrinsic self-processing. We discuss studies on self-related processing in psychotic disorders that provide converging evidence for disrupted communication between neural networks subserving the so-called intrinsic self and extrinsic self. This disruption might be mainly caused by impaired integrity of key brain hubs. The intrinsic self has been associated with cortical midline structures involved in self-referential processing, autobiographical memory, and emotional evaluation. Additionally, we highlight central aspects of the extrinsic self in its interaction with the environment using sensorimotor networks, including self-experience in sensation and actions. A deficient relationship between these self-aspects because of disrupted between-network interactions offers a framework to explain core clinical features of psychotic disorders. In particular, we show how relative isolation and reduced modularity of networks subserving intrinsic and extrinsic self-processing might trigger the emergence of hallucinations and delusions, and why patients with psychosis typically have difficulties with self-other relationships and do not recognise mental problems.

Recent Neurobiological Insights into the Concept of Insight in Psychosis

The concept of insight in psychosis has been an interesting area in clinical psychiatry for well over a century with a surge in research interest over the past 25 years. Moreover, the past 5 years have been particularly fruitful in deciphering its neurobiological underpinnings. This article presents the development of the concept of insight in psychosis and reviews the current neurobiological research findings in this area.

Is it me? Verbal self-monitoring neural network and clinical insight in schizophrenia

Self-monitoring, defined as the ability to distinguish between self-generated stimuli from other-generated ones, is known to be impaired in schizophrenia. This impairment has been theorised as the basis for many of the core psychotic symptoms, in particular, poor clinical insight. This study aimed to investigate verbal self-monitoring related neural substrates of preserved and poor clinical insight in schizophrenia. It involved 40 stable schizophrenia outpatients, 20 with preserved and 20 with poor insight, and 20 healthy participants. All participants underwent functional magnetic resonance imaging with brain coverage covering key areas in the self-monitoring network during a verbal self-monitoring task. Healthy participants showed higher performance accuracy and greater thalamic activity than both preserved and poor insight patient groups. Preserved insight patients showed higher activity in the putamen extending into the caudate, insula and inferior frontal gyrus, compared to poor insight patients, and in the anterior cingulate and medial frontal gyrus, compared to healthy participants. Poor insight patients did not show greater activity in any brain area compared to preserved insight patients or healthy participants. Future studies may pursue therapeutic avenues, such as meta-cognitive therapies to promote self-monitoring or targeted stimulation of relevant brain areas, as means of enhancing insight in schizophrenia.