The metabolic basis of cognitive insight in psychosis: A positron emission tomography study

Measuring Brain Temperature in Youth Bipolar Disorder Using a Novel Magnetic Resonance Imaging Approach: A Proof-of-concept Study

BACKGROUND

There is evidence of alterations in mitochondrial energy metabolism and cerebral blood flow (CBF) in adults and youth with bipolar disorder (BD). Brain thermoregulation is based on the balance of heat-producing metabolism and heat-dissipating mechanisms, including CBF.

OBJECTIVE

To examine brain temperature, and its relation to CBF, in relation to BD and mood symptom severity in youth.

METHODS

This study included 25 youth participants (age 17.4 ± 1.7 years; 13 BD, 12 control group (CG)). Magnetic resonance spectroscopy data were acquired to obtain brain temperature in the left anterior cingulate cortex (ACC) and the left precuneus. Regional estimates of CBF were provided by arterial spin labeling imaging. Analyses used general linear regression models, covarying for age, sex, and psychiatric medications.

RESULTS

Brain temperature was significantly higher in BD compared to CG in the precuneus. A higher ratio of brain temperature to CBF was significantly associated with greater depression symptom severity in both the ACC and precuneus within BD. Analyses examining the relationship of brain temperature or CBF with depression severity score did not reveal any significant finding in the ACC or the precuneus.

CONCLUSION

The current study provides preliminary evidence of increased brain temperature in youth with BD, in whom reduced thermoregulatory capacity is putatively associated with depression symptom severity. Evaluation of brain temperature and CBF in conjunction may provide valuable insight beyond what can be gleaned by either metric alone. Larger prospective studies are warranted to further evaluate brain temperature and its association with CBF concerning BD.

Frontotemporal Dementia and Late-Onset Bipolar Disorder: The Many Directions of a Busy Road

It is a common pathway for patients with the behavioral variant of frontotemporal dementia (bvFTD) to be first misdiagnosed with a primary psychiatric disorder, a considerable proportion of them being diagnosed with bipolar disorder (BD). Conversely, not rarely patients presenting in late life with a first episode of mania or atypically severe depression are initially considered to have dementia before the diagnosis of late-onset BD is reached. Beyond some shared features that make these conditions particularly prone to confusion, especially in the elderly, the relationship between bvFTD and BD is far from simple. Patients with BD often have cognitive complaints as part of their psychiatric disorder but are at an increased risk of developing dementia, including FTD. Likewise, apathy and disinhibition, common features of depression and mania, respectively, are among the core features of the bvFTD syndrome, not to mention that depression may coexist with dementia. In this article, we take advantage of the current knowledge on the neurobiology of these two nosologic entities to review their historical and conceptual interplay, highlighting the clinical, genetic and neuroimaging features that may be shared by both disorders or unique to each of them.

Trait self-reflectiveness relates to time-varying dynamics of resting state functional connectivity and underlying structural connectomes: Role of the default mode network

BACKGROUND

Cognitive insight is defined as the ability to reflect upon oneself (i.e. self-reflectiveness), and to not be overly confident of one's own (incorrect) beliefs (i.e. self-certainty). These abilities are impaired in several disorders, while they are essential for the evaluation and regulation of one's behavior. We hypothesized that cognitive insight is a dynamic process, and therefore examined how it relates to temporal dynamics of resting state functional connectivity (FC) and underlying structural network characteristics in 58 healthy individuals.

METHODS

Cognitive insight was measured with the Beck Cognitive Insight Scale. FC characteristics were calculated after obtaining four FC states with leading eigenvector dynamics analysis. Gray matter (GM) and DTI connectomes were based on GM similarity and probabilistic tractography. Structural graph characteristics, such as path length, clustering coefficient, and small-world coefficient, were calculated with the Brain Connectivity Toolbox. FC and structural graph characteristics were correlated with cognitive insight.

RESULTS

Individuals with lower cognitive insight switched more and spent less time in a globally synchronized state. Additionally, individuals with lower self-reflectiveness spent more time in, had a higher probability of, and had a higher chance of switching to a state entailing default mode network (DMN) areas. With lower self-reflectiveness, DTI-connectomes were segregated less (i.e. lower global clustering coefficient) with lower embeddedness of the left angular gyrus specifically (i.e. lower local clustering coefficient).

CONCLUSIONS

Our results suggest less stable functional and structural networks in individuals with poorer cognitive insight, specifically self-reflectiveness. An overly present DMN appears to play a key role in poorer self-reflectiveness.

Impulsivity issues in borderline personality disorder and it's links with insight: the role of urgency

Objective

Impulsivity plays a major role in a wide range of disorders including Borderline Personality Disorder. Another crucial clinical dimension is insight. This clinical dimension is linked with symptomatology and treatment issue. The present study aims to investigate the impact of positive and negative urgency on insight in Borderline Personality Disorder.

Methods

We recruited eighty-one women with Borderline Personality Disorder and assessed insight level and impulsivity scores using the Beck Cognitive insight scale and the UPPS-short form scale.

Results

Our results showed interesting links between positive urgency and insight quality.

Conclusion

Negative emotions play a fundamental role for the insight quality, but positive emotions are surprisingly related to clinical insight. We discuss the possible therapeutical impact of this results on treatment adaptation.

Cultural differences and neural correlates of cognitive insight in schizophrenia

Cognitive insight refers to a person's ability to examine their psychotic experiences and the inferences they draw from these experiences. Several studies suggest that cultural factors influence cognitive insight and the processes involved therein; a few studies have suggested differences between Western and Asian societies. However, there are no studies on cognitive insight and its neural correlates in non-Western populations. Hence, we examined factor structure of Beck's cognitive insight scale (BCIS) in a large sample of patients with schizophrenia (SCZ) and healthy volunteers (HV) from India and assessed the relationship between cortical thickness and cognitive insight. We recruited 240 participants (SCZ-140; HV-100). Of these, 58 participants (SCZ-33; HV-25) underwent magnetic resonance imaging. We found a three-factor structure for BCIS which is different from the original two factor structure; self-reflection (SR) of original two-factor structure was sub-divided into- SR1, introspection and SR2, openness to feedback. There was a significant difference between HV and SCZ in the new factors, SR1 and SR2 but not in the original SR factor. Difference was also seen on MRI analysis; while there was a significant positive correlation between original SR factor and thickness of right posterior cingulate cortex, SR2 was positively correlated with thickness of left ventrolateral prefrontal cortex. The difference in factor structure in Indian participants and their distinct neural correlates point to cultural differences in cognitive insight. While in western societies the constructs of introspection and openness to feedback might integrate, they might be separate entities in Asian population.

Structural and metabolic cerebral alterations between elderly bipolar disorder and behavioural variant frontotemporal dementia: A combined MRI-PET study

BACKGROUND

Elderly bipolar disorder (BD) and behavioural variant of frontotemporal dementia (bvFTD) may exhibit similar symptoms and both disorders are characterized by selective abnormalities in cortical and subcortical regions that are associated with cognitive and emotional impairments. We aimed to investigate common and distinct neural substrates of BD and bvFTD by coupling, for the first time, magnetic resonance imaging (MRI) and positron emission tomography (PET) techniques.

METHODS

3-Tesla MRI and 18 fluorodeoxyglucose-PET scans were acquired for 16 elderly BD patients, 23 bvFTD patients with mild cognitive impairments and 68 healthy controls (48 for PET and 20 for MRI analyses).

RESULTS

BD and bvFTD patients exhibit a different localization of grey matter reductions in the lateral prefrontal cortex, with the first group showing grey matter decrease in the ventrolateral prefrontal cortex and the latter group showing grey matter reductions in the dorsolateral prefrontal cortex as well as unique grey matter and metabolic alterations within the orbitofrontal cortex. The bvFTD group also displayed unique volumetric shrinkage in regions within the temporo-parietal network together with greater metabolic impairments within the temporal cortex and more extensive volumetric and metabolic abnormalities within the limbic lobe. Finally, while the BD group showed greater grey matter volumes in caudate nucleus, bvFTD subjects displayed lower metabolism.

CONCLUSION

This MRI-PET study explored, for the first time to the best of our knowledge, structural and functional abnormalities in bvFTD and elderly BD patients, with the final aim of identifying the specific biological signature of these disorders, which might have important implications not only in prevention but also in differential diagnosis and treatment.

The metabolic basis of psychosis in bipolar disorder: A positron emission tomography study

OBJECTIVES

Psychotic symptoms are a common feature in bipolar disorder (BD), especially during manic phases, and are associated with a more severe course of illness. However, not all bipolar subjects experience psychosis during the course of their illness, and this difference often guides assessment and pharmacological treatment. The aim of the present study is to elucidate, for the first time, the FDG uptake dysfunctions associated with psychosis in BD patients with and without a history of past psychotic symptoms, through a positron emission tomography (PET) approach.

METHODS

Fifty BD patients with lifetime psychotic symptoms, 40 BD patients without lifetime psychotic symptoms and 27 healthy controls (HC) were recruited and underwent an 18F-FDG-PET session.

RESULTS

Compared to HC, BD subjects shared common FDG uptake deficits in several brain areas, including insula, inferior temporal gyrus and middle occipital gyrus. Moreover, we found that BD patients with a history of past psychotic symptoms had a unique FDG uptake alteration in the right fusiform gyrus compared to both BD patients without lifetime psychotic symptoms and HC (all P < 0.01, cFWE corrected).

CONCLUSIONS

Overall, our results suggest that FDG uptake alterations in brain regions involved in emotion regulation are a key feature of BD, regardless the presence of past psychosis. Finally, we demonstrated that the FDG uptake reduction in fusiform gyrus is associated with the presence of past psychotic symptoms in BD, ultimately leading towards the idea that the fusiform gyrus might be considered a putative biomarker of psychosis.

The longitudinal course of cognitive insight and mood in bipolar disorder

Cognitive insight or the ability to be self-reflective and to retain from being over-confident in own beliefs is an upcoming topic in research regarding psychiatric disorders. In bipolar disorder investigations are scarce and an important lacuna is the unexamined longitudinal relationship between cognitive insight and mood. Therefore, in this study the level of cognitive insight, mania and depression were assessed in a total of 56 patients with bipolar disorder at baseline, four months and eight months follow-up. In addition, the cognitive insight of 35 healthy controls was assessed at baseline and at four months follow-up. The current research shows that self-reflectiveness and self-certainty remained stable over time in bipolar disorder. The improvement of mood did not affect the course of cognitive insight. However, at baseline higher levels of depression were correlated with more self-reflectiveness. In addition, self-reflectiveness was higher for bipolar disorder patients in comparison with the healthy controls. Our results could imply that higher levels of self-reflectiveness are a specific characteristic in bipolar disorder that is independent from an improvement in mood.