Shared and differential cortical functional abnormalities associated with inhibitory control in patients with schizophrenia and bipolar disorder

Impulsivity and neural correlates of response inhibition in bipolar disorder and their unaffected relatives: A MEG study

BACKGROUND

Response inhibition is a core cognitive impairment in bipolar disorder (BD), leading to increased impulsivity in BD. However, the relationship between the neural mechanisms underlying impaired response inhibition and impulsivity in BD is not yet clear. Individuals who are genetically predisposed to BD give a way of identifying potential endophenotypes.

METHODS

A total of 97 participants, including 39 patients with BD, 22 unaffected relatives (UR) of patients with BD, and 36 healthy controls performed a Go/No-Go task during magnetoencephalography. We carried out time-frequency and connectivity analysis on MEG data.

RESULTS

Decreased beta power, prolonged latency and increased peak frequency in rIFG, decreased beta power in pre-SMA and reduced rIFG-to-pre-SMA connectivity were found in BD relative to healthy controls. In the UR group, we found a decrease in the beta power of pre-SMA and prolonged latency of rIFG. Furthermore, increased motor impulsiveness in BD was related to abnormal alterations in beta oscillatory activity of rIFG and functional connectivity between rIFG and pre-SMA.

CONCLUSIONS

Hypoactivity activity in rIFG and impaired dominant role of rIFG in the prefrontal control network may underlie the neuropathology of response inhibition dysfunction, resulting increased motor impulsivity in BD. Our findings point to measuring rIFG dysfunction as a potential means of identifying individuals at genetic high risk for transition to BD disease expression.

Peripheral inflammation is associated with impairments of inhibitory behavioral control and visual sensorimotor function in psychotic disorders

Elevated markers of peripheral inflammation are common in psychosis spectrum disorders and have been associated with brain anatomy, pathology, and physiology as well as clinical outcomes. Preliminary evidence suggests a link between inflammatory cytokines and C-reactive protein (CRP) with generalized cognitive impairments in a subgroup of individuals with psychosis. Whether these patients with elevated peripheral inflammation demonstrate deficits in specific cognitive domains remains unclear. To examine this, seventeen neuropsychological and sensorimotor tasks and thirteen peripheral inflammatory and microvascular markers were quantified in a subset of B-SNIP consortium participants (129 psychosis, 55 healthy controls). Principal component analysis was conducted across the inflammatory markers, resulting in five inflammation factors. Three discrete latent cognitive domains (Visual Sensorimotor, General Cognitive Ability, and Inhibitory Behavioral Control) were characterized based on the neurobehavioral battery and examined in association with inflammation factors. Hierarchical clustering analysis identified cognition-sensitive high/low inflammation subgroups. Among persons with psychotic disorders but not healthy controls, higher inflammation scores had significant associations with impairments of Inhibitory Control (R2 = 0.100, p-value = 2.69e-4, q-value = 0.004) and suggestive associations with Visual Sensorimotor function (R2 = 0.039, p-value = 0.024, q-value = 0.180), but not with General Cognitive Ability (R2 = 0.015, p-value = 0.162). Greater deficits in Inhibitory Control were observed in the high inflammation patient subgroup, which represented 30.2 % of persons with psychotic disorders, as compared to the low inflammation psychosis subgroup. These findings indicate that inflammation dysregulation may differentially impact specific neurobehavioral domains across psychotic disorders, particularly performance on tasks requiring ongoing behavioral monitoring and control.

Aberrant topology of white matter networks in patients with methamphetamine dependence and its application in support vector machine-based classification

Brain white matter (WM) networks have been widely studied in neuropsychiatric disorders. However, few studies have evaluated alterations in WM network topological organization in patients with methamphetamine (MA) dependence. Therefore, using machine learning classification methods to analyze WM network topological attributes may give new insights into patients with MA dependence. In the study, diffusion tensor imaging-based probabilistic tractography was used to map the weighted WM networks in 46 MA-dependent patients and 46 control subjects. Using graph-theoretical analyses, the global and regional topological attributes of WM networks for both groups were calculated and compared to determine inter-group differences using a permutation-based general linear model. In addition, the study used a support vector machine (SVM) learning approach to construct a classifier for discriminating subjects with MA dependence from control subjects. Relative to the control group, the MA-dependent group exhibited abnormal topological organization, as evidenced by decreased small-worldness and modularity, and increased nodal efficiency in the right medial superior temporal gyrus, right pallidum, and right ventromedial putamen; the MA-dependent group had the higher hubness scores in 25 regions, which were mainly located in the default mode network. An SVM trained with topological attributes achieved classification accuracy, sensitivity, specificity, and kappa values of 98.09% ± 2.59%, 98.24% ± 4.00%, 97.94% ± 4.26%, and 96.18% ± 5.19% for patients with MA dependence. Our results may suggest altered global WM structural networks in MA-dependent patients. Furthermore, the abnormal WM network topological attributes may provide promising features for the construction of high-efficacy classification models.

Neural correlates of impulsivity in bipolar disorder: A systematic review and clinical implications

Impulsivity is a common feature of bipolar disorder (BD) with ramifications for functional impairment and premature mortality. This PRISMA-guided systematic review aims to integrate findings on the neurocircuitry associated with impulsivity in BD. We searched for functional neuroimaging studies that examined rapid-response impulsivity and choice impulsivity using the Go/No-Go Task, Stop-Signal Task, and Delay Discounting Task. Findings from 33 studies were synthesized with an emphasis on the effect of mood state of the sample and affective salience of the task. Results suggest trait-like brain activation abnormalities in regions implicated in impulsivity that persist across mood states. During rapid-response inhibition, BD exhibit under-activation of key frontal, insular, parietal, cingulate, and thalamic regions, but over-activation of these regions when the task involves emotional stimuli. Delay discounting tasks with functional neuroimaging in BD are lacking, but hyperactivity of orbitofrontal and striatal regions associated with reward hypersensitivity may be related to difficulty delaying gratification. We propose a working model of neurocircuitry dysfunction underlying behavioral impulsivity in BD. Clinical implications and future directions are discussed.

Characteristics of prefrontal activity during emotional and cognitive processing in patients with bipolar disorder: A multi-channel functional near-infrared spectroscopy study

Bipolar disorder (BD) is a recurrent chronic mental disorder with a broad profile of functional deficits including disturbed emotional processing and cognitive impairments. The goal of the current study was to further explore the underlying neural mechanism of dysfunction in patients with BD from a comprehensive perspective of both cognition and emotion. Forty-six clinical patients with BD and forty-five healthy controls performed emotion induction task and verbal fluency task (VFT), with frontal activity measured by functional near-infrared spectroscopy (fNIRS). Our results show distinct hemodynamic activity in the prefrontal region during emotional and cognitive processing between patients with BD and healthy controls. Patients with BD exhibit valence-dependent prefrontal cortex (PFC) hemodynamic response to emotional stimuli, with bilateral frontal hypoactivity indicating decreased positive reactivity and left frontal hyperactivity indicating increased negative reactivity. On the other hand, patients with BD showed impaired performance with bilateral frontal hypoactivity during VFT. Taken together, frontal dysfunction of cognition and emotionality in patients with BD probed by fNIRS would be a potential biomarker in clinical assessment.

Visual Event-Related Potentials under External Emotional Stimuli in Bipolar I Disorder with and without Hypersexuality

Hypersexuality is related to functions of personality and emotion and is a salient symptom of bipolar I disorder especially during manic episode. However, it is uncertain whether bipolar I disorder with (BW) and without (BO) hypersexuality exhibits different cerebral activations under external emotion stimuli. In 54 healthy volunteers, 27 BW and 26 BO patients, we administered the visual oddball event-related potentials (ERPs) under external emotions of Disgust, Erotica, Fear, Happiness, Neutral, and Sadness. Participants’ concurrent states of mania, hypomania, and depression were also evaluated. The N1 latencies under Erotica and Happiness were prolonged, and the P3b amplitudes under Fear and Sadness were decreased in BW; the P3b amplitudes under Fear were increased in BO. The parietal, frontal, and occipital activations were found in BW, and the frontal and temporal activations in BO under different external emotional stimuli, respectively. Some ERP components were correlated with the concurrent affective states in three groups of participants. The primary perception under Erotica and Happiness, and voluntary attention under Fear and Sadness, were impaired in BW, while the voluntary attention under Fear was impaired in BO. Our study indicates different patterns of visual attentional deficits under different external emotions in BW and BO.

Association between resting-state functional connectivity of amygdala subregions and peripheral pro-inflammation cytokines levels in bipolar disorder

The pathophysiological mechanisms of bipolar disorder (BD) are not completely known, and systemic inflammation and immune dysregulation are considered as risk factors. Previous neuroimaging studies have proved metabolic, structural and functional abnormalities of the amygdala in BD, suggesting the vital role of amygdala in BD patients. This study aimed to test the underlying neural mechanism of inflammation-induced functional connectivity (FC) in the amygdala subregions of BD patients. Resting-state functional MRI (rs-fMRI) was used to delineate the amygdala FC from two pairs of amygdala seed regions (the bilateral lateral and medial amygdala) in 51 unmedicated BD patients and 69 healthy controls (HCs). The levels of pro-inflammatory cytokines including interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α were measured in the serum. The correlation between abnormal levels of pro-inflammatory cytokines and FC values were calculated in BD patients. The BD group exhibited decreased FC between the right medial amygdala and bilateral medial frontal cortex (MFC), and decreased FC between the left medial amygdala and the left temporal pole (TP), right orbital inferior frontal gyrus compared with HCs. The BD patients had higher levels of TNF-α than HCs. Correlation analysis showed negative correlation between the TNF-α level and abnormal FC of the right medial amygdala-bilateral MFC; and negative correlation between TNF-α levels and abnormal FC of the left medial amygdala-left TP in BD group. These findings suggest that dysfunctional and immune dysregulation between the amygdala and the frontotemporal circuitry might play a critical role in the pathogenesis of BD.

Increased prefrontal cortex activity on near-infrared spectroscopy after interpersonal counseling in individuals with attention deficit hyperactivity disorder

[Purpose] The number of patients with attention deficit hyperactivity disorder has been increasing. These patients show low activity in the prefrontal cortex, which can be improved by pharmacotherapy and neurofeedback training. This exploratory study aimed to examine whether the hemodynamic response in the prefrontal cortex during an inhibition response in patients with attention deficit hyperactivity disorder tendencies increased after interpersonal counseling. [Participants and Methods] Participants (n=5) received three interpersonal counseling sessions. Interpersonal counseling focuses on the patient’s current problems and devises specific coping strategies, and it can be performed by healthcare personnel such as physiotherapists. Prefrontal cortex activity during a suppression reaction task was measured by using near-infrared spectroscopy at baseline and post-interpersonal counseling. The outcome was a difference in the oxyhemoglobin level from baseline to post-interpersonal counseling. [Results] The oxyhemoglobin level in the prefrontal cortex significantly increased post-interpersonal counseling. [Conclusion] These results suggested that interpersonal counseling could improve the hemodynamic response in the prefrontal cortex under inhibition in individuals with attention deficit hyperactivity disorder tendencies, suggesting that interpersonal counseling may be effective for treating attention deficit hyperactivity disorder symptoms.

Frozen in (e)motion: How reactive motor inhibition is influenced by the emotional content of stimuli in healthy and psychiatric populations

Efficient inhibitory control is vital. However, environmental cues can influence motor control especially in an emotional context. One common task to measure inhibitory control is the stop-signal task (SST), which asks participants to respond to go stimuli knowing that on some trials a stop signal will be presented, requiring them to inhibit their response. This paradigm estimates the ability to inhibit already-initiated responses by calculating participants' stop-signal reaction times (SSRT), an index of inhibitory control. Here, we aim to review the existing, often contradictory, evidence on the influence of emotional stimuli on the inhibitory process. We aim to discuss which factors may reveal an interference as well as an advantage of emotional stimuli on action inhibition performance. Finally, we review the existing evidence that has investigated the effect of such stimuli on action inhibition in the psychiatric population. Important factors are the relevance, the intensity and the valence of the emotional stimulus, as well as the affected component of the motor control. From all this evidence, it is clear that understand precisely how emotion is integrated into core executive functions, such as inhibitory control, is essential not only for cognitive neuroscience, but also for refining neurocognitive models of psychopathology.

Altered Effective Connectivity within an Oculomotor Control Network in Unaffected Relatives of Individuals with Schizophrenia

The ability to rapidly stop or change a planned action is a critical cognitive process that is impaired in schizophrenia. The current study aimed to examine whether this impairment reflects familial vulnerability to schizophrenia across two experiments comparing unaffected first-degree relatives to healthy controls. First, we examined performance on a saccadic stop-signal task that required rapid inhibition of an eye movement. Then, in a different sample, we investigated behavioral and neural responses (using fMRI) during a stop-signal task variant that required rapid modification of a prepared eye movement. Here, we examined differences between relatives and healthy controls in terms of activation and effective connectivity within an oculomotor control network during task performance. Like individuals with schizophrenia, the unaffected relatives showed behavioral evidence for more inefficient inhibitory processes. Unlike previous findings in individuals with schizophrenia, however, the relatives showed evidence for a compensatory waiting strategy. Behavioral differences were accompanied by more activation among the relatives in task-relevant regions across conditions and group differences in effective connectivity across the task that were modulated differently by the instruction to exert control over a planned saccade. Effective connectivity parameters were related to behavioral measures of inhibition efficiency. The results suggest that individuals at familial risk for schizophrenia were engaging an oculomotor control network differently than controls and in a way that compromises inhibition efficiency.

Altered effective connectivity within an oculomotor control network in individuals with schizophrenia

Rapid inhibition or modification of actions is a crucial cognitive ability, which is impaired in persons with schizophrenia (SZP). Primate neurophysiology studies have identified a network of brain regions that subserves control over gaze. Here, we examine effective connectivity within this oculomotor control network in SZP and healthy controls (HC). During fMRI, participants performed a stop-signal task variant in which they were instructed to saccade to a visual target (no-step trials) unless a second target appeared (redirect trials); on redirect trials, participants were instructed to inhibit the planned saccade and redirect to the new target. We compared functional responses on redirect trials to no-step trials and used dynamic causal modelling (DCM) to examine group differences in network effective connectivity. Behaviorally, SZP were less efficient at inhibiting, which was related to their employment status. Compared to HC, they showed a smaller difference in activity between redirect trials and no-step trials in frontal eye fields (FEF), supplementary eye fields (SEF), inferior frontal cortex (IFC), thalamus, and caudate. DCM analyses revealed widespread group differences in effective connectivity across the task, including different patterns of self-inhibition in many nodes in SZP. Group differences in how effective connectivity was modulated on redirect trials revealed differences between the FEF and SEF, between the SEF and IFC, between the superior colliculus and the thalamus, and self-inhibition within the FEF and caudate. These results provide insight into the neural mechanisms of inefficient inhibitory control in individuals with schizophrenia.

Shared polygenic risk for ADHD, executive dysfunction and other psychiatric disorders

Many psychiatric disorders are associated with impaired executive functioning (EF). The associated EF component varies by psychiatric disorders, and this variation might be due to genetic liability. We explored the genetic association between five psychiatric disorders and EF in clinically-recruited attention deficit hyperactivity disorder (ADHD) children using polygenic risk score (PRS) methodology. Genome-wide association study (GWAS) summary data for ADHD, major depressive disorder (MDD), schizophrenia (SZ), bipolar disorder (BIP) and autism were used to calculate the PRSs. EF was evaluated by the Stroop test for inhibitory control, the trail-making test for cognitive flexibility, and the digital span test for working memory in a Chinese ADHD cohort (n = 1147). Exploratory factor analysis of the three measures identified one principal component for EF (EF-PC). Linear regression models were used to analyze the association between each PRS and the EF measures. The role of EF measures in mediating the effects of the PRSs on ADHD symptoms was also analyzed. The result showed the PRSs for MDD, ADHD and BIP were all significantly associated with the EF-PC. For each EF component, the association results were different for the PRSs of the five psychiatric disorders: the PRSs for ADHD and MDD were associated with inhibitory control (adjusted P = 0.0183 and 0.0313, respectively), the PRS for BIP was associated with working memory (adjusted P = 0.0416), and the PRS for SZ was associated with cognitive flexibility (adjusted P = 0.0335). All three EF measures were significantly correlated with ADHD symptoms. In mediation analyses, the ADHD and MDD PRSs, which were associated with inhibitory control, had significant indirect effects on ADHD symptoms through the mediation of inhibitory control. These findings indicate that the polygenic risks for several psychiatric disorders influence specific executive dysfunction in children with ADHD. The results helped to clarify the relationship between risk genes of each mental disorder and the intermediate cognitive domain, which may further help elucidate the risk genes and motivate efforts to develop EF measures as a diagnostic marker and future treatment target.

Cognitive Functioning and Schizotypy: A Four-Years Study

Although there is ample evidence from cross-sectional studies indicating cognitive deficits in high schizotypal individuals that resemble the cognitive profile of schizophrenia-spectrum patients, there is still lack of evidence by longitudinal/follow-up studies. The present study included assessments of schizotypal traits and a wide range of cognitive functions at two time points (baseline and 4-years assessments) in order to examine (a) their stability over time, (b) the predictive value of baseline schizotypy on cognition at follow-up and (c) differences in cognition between the two time points in high negative schizotypal and control individuals. Only high negative schizotypal individuals were compared with controls due to the limited number of participants falling in the other schizotypal groups at follow-up. Seventy participants (mean age: 36.17; 70% females) were assessed at baseline and follow-up. Schizotypal traits were evaluated with the Schizotypal Personality Questionnaire. We found that schizotypal traits decreased over time, except in a sub-group of participants ("schizotypy congruent") that includes individuals who consistently meet normative criteria of inclusion in either a schizotypal or control group. In these individuals, negative schizotypy and aspects of cognitive-perceptual and disorganized schizotypy remained stable. The stability of cognitive functioning also varied over time: response inhibition, aspects of cued attention switching, set-shifting and phonemic/semantic verbal fluency improved at follow-up. High negative schizotypy at baseline predicted poorer response inhibition and semantic switching at follow-up while high disorganized schizotypy predicted poorer semantic processing and complex processing speed/set-shifting. The between-group analyses revealed that response inhibition, set-shifting and complex processing speed/set-shifting were poorer in negative schizotypals compared with controls at both time points, while maintaining set and semantic switching were poorer only at follow-up. Taken together, the findings show differential stability of the schizotypal traits over time and indicate that different aspects of schizotypy predict a different pattern of neuropsychological task performance during a 4-years time window. These results are of significant use in the formulation of targeted early-intervention strategies for high-risk populations.