Neural correlate of impulsivity in subjects at ultra-high risk for psychosis

Impulsivity as a predictor of clinical and psychological outcomes in a naturalistic prospective cohort of subjects at ultra-high risk (UHR) for psychosis from Tunisia

BACKGROUND

Impulsivity is associated with serious detrimental consequences on physical, mental, behavioral and social aspects of health among patients with psychosis. The present prospective 12-month follow-up study aimed to determine the prevalence of highly impulsive individuals among Ultra High Risk (UHR) patients, how impulsivity evolves over the follow-up period, and whether impulsivity impacts clinical, psychological and functional outcomes in this population.

METHOD

UHR patients were invited to complete a battery of measurements at three-time points: at baseline, and at 6 and 12 months of follow-up. Impulsivity was assessed using both behavioral (the Wisconsin Card Sorting Test, WCST) and self-report (the Barratt Impulsiveness Scale, BIS-11) measures.

RESULTS

Findings showed that at 6 months of follow-up, higher 6-month BIS-11 attentional and motor impulsivity were significantly associated with lower quality of life and greater general psychological distress. In addition, higher baseline BIS-11 motor impulsivity significantly predicted more severe positive psychotic symptoms at 12 months of follow-up. However, WCST scores did not show any significant associations with study variables at the different times of follow-up.

CONCLUSION

Interventions targeting impulsivity in UHR individuals could help decrease psychological distress and positive psychotic symptoms' severity, as well as improve quality of life in UHR individuals.

Network Analysis of the Structure of the Core Symptoms and Clinical Correlates in Comorbid Schizophrenia and Gambling Disorder

Few studies have analyzed the clinical profile of treatment-seeking patients with the comorbid presence of schizophrenia (SCZ) and gambling disorder (GD), which warrants new research to assess the network structure of this complex mental condition. The aim of this study was to explore the organization of the symptoms and other clinical correlates of SCZ with GD. Network analysis was applied to a sample of N = 179 SCZ patients (age range: 19-70 years, mean=39.5, SD=9.9) who met clinical criteria for gambling disorder-related problems. Variables included in the network were the core GD symptoms according to the DSM-5, psychotic and paranoid ideation levels, global psychological distress, GD severity measures (debts and illegal behavior related with gambling), substances (tobacco, alcohol, and illegal drugs), and personality profile. The nodes with the highest authority in the network (variables of highest relevance) were personality traits and psychological distress. Four empirical modules/clusters were identified, and linkage analysis identified the nodes with the highest closeness (bridge nodes) to be novelty seeking and reward dependence (these traits facilitate the transition between the modules). Identification of the variables with the highest centrality/linkage can be particularly useful for developing precise management plans to prevent and treat SCZ with GD.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11469-022-00983-y.

Cortical surface variation in individuals with excessive smartphone use

Excessive smartphone use has been repeatedly related to adverse effects on mental health and psychological well-being in young adults. The continued investigation of the neurobiological mechanism underlying excessive smartphone use - sometimes also referred to as "smartphone addiction" (SPA) - is considered a top priority in system neuroscience research. Despite progress in the past years, cortical morphology associated with SPA is still poorly understood. Here, we used structural magnetic resonance imaging (MRI) at 3 T to investigate two cortical surface markers of distinct neurodevelopmental origin such as the complexity of cortical folding (CCF) and cortical thickness (CTh) in individuals with excessive smartphone use (n = 19) compared to individuals not fulfilling SPA criteria (n-SPA; n = 22). SPA was assessed using the Smartphone Addiction Inventory (SPAI). CCF and CTh were investigated using the Computational Anatomy Toolbox (CAT12). SPA individuals showed lower CCF in the right superior frontal gyrus as well as in the right caudal (cACC) and rostral anterior cingulate cortex (rACC) compared to n-SPA individuals (TFCE, uncorrected at p < 0.001). Following a dimensional approach, across the entire sample CCF of the right cACC was significantly associated with SPAI total score, as well as with distinct SPAI subdimensions, particularly time spent with the device, compulsivity, and sleep interference in all participants (n = 41; p < 0.05, FDR-corrected). Collectively, these findings suggest that SPA is associated with aberrant structural maturation of regions important for cognitive control and emotional regulation. This article is protected by copyright. All rights reserved.

The prevalence and features of schizophrenia among individuals with gambling disorder

BACKGROUND-OBJECTIVES

Few studies have analyzed the comorbid presence of gambling disorder (GD) with schizophrenia, its sociodemographic correlates and clinical implications. This study estimated the prevalence of the dual diagnosis (GD with schizophrenia) and the differences in the profiles of patients with and without the dual condition.

METHOD

The sample included n = 3,754 patients consecutively accepted for treatment for GD. Sociodemographics, gambling-related variables, psychopathological state and personality traits were assessed and compared between the groups.

RESULTS

The prevalence of schizophrenia within patients who met clinical criteria for GD was 4.4% (95% confidence interval: 3.8%-5.1%). Variables related to the dual presence of GD with schizophrenia were single marital status, lower education level, inactive working status, socioeconomic disadvantage, younger age, earlier onset of gambling problems, worse global psychopathological state and more dysfunctional personality profile (higher level in harm avoidance and lower level in cooperativeness, reward dependence, persistence and self-directedness).

CONCLUSION

The presence of schizophrenia among patients with GD was around 4 times higher than the prevalence rate estimated in the reference general population. The differences in the profiles of GD patients with and without schizophrenia suggest that individuals with the dual diagnosis condition require unique assessment considerations and tailored treatment interventions specifically designed for the clinical and functioning higher risk.

Cingulate white matter volume and associated cognitive and behavioral impulsivity in Veterans with a history of suicide behavior

BACKGROUND

Suicide is one of the leading causes of death for military personnel and Veterans. Neuroimaging studies have revealed abnormalities in white matter tracts and brain connectivity in suicide behavior (SB); however, reports of alterations in white matter volume and its association with related behaviors are limited. The current study examined the relationship between cingulate white matter volume (WMV), impulsivity, and SB in Veterans.

METHODS

Fifty-two Veterans, ages 18 to 65, underwent magnetic resonance imaging on a 3T Siemens Verio scanner. Morphometric analysis of brain images was performed to evaluate differences in WMV in cingulate regions of interest. Participants completed the Columbia Suicide Severity Rating Scale to assess lifetime suicide behavior and the Barratt Impulsivity Scale (BIS) and the Continuous Performance Test (CPT) to assess impulsivity.

RESULTS

Twenty-nine Veterans had a history of suicidal ideation (SI) and 23 had a history of suicide attempts (SA). Controlling for age, sex, handedness and total white matter volume, reduced WMV was observed in the left rostral anterior cingulate cortex (rACC) in Veterans with SA relative to Veterans with SI, p = .008. Additionally, non-planning on the BIS was negatively correlated with left rACC WMV for Veterans with a history of SA, p = .04. Other subregions of the ACC WMV were negatively correlated with planning and attention impulsivity (BIS) and omission and commission errors (CPT) for attempters.

CONCLUSIONS

Reduction in rACC WMV in Veterans with SA was negatively correlated with nonplanning measures. These findings are consistent with ACC involvement in inhibitory processes and build on evidence that SB is associated with neurobiological abnormalities and suggest that white matter changes may be related to actual attempts.

Predicting the individual risk of psychosis conversion in at-risk mental state (ARMS): a multivariate model reveals the influence of nonpsychotic prodromal symptoms

To improve the prediction of the individual risk of conversion to psychosis in UHR subjects, by considering all CAARMS' symptoms at first presentation and using a multivariate machine learning method known as logistic regression with Elastic-net shrinkage. 46 young individuals who sought help from the specialized outpatient unit at Sainte-Anne hospital and who met CAARMS criteria for UHR were assessed, among whom 27 were reassessed at follow-up (22.4 ± 6.54 months) and included in the analysis. Elastic net logistic regression was trained, using CAARMS items at baseline to predict individual evolution between converters (UHR-P) and non-converters (UHR-NP). Elastic-net was used to select the few CAARMS items that best predict the clinical evolution. All validations and significances of predictive models were computed with non-parametric re-sampling strategies that provide robust estimators even when the distributional assumption cannot be guaranteed. Among the 25 CAARMS items, the Elastic net selected 'obsessive-compulsive symptoms' and 'aggression/dangerous behavior' as risk factors for conversion while 'anhedonia' and 'mood swings/lability' were associated with non-conversion at follow-up. In the ten-fold stratified cross-validation, the classification achieved 81.8% of sensitivity (P = 0.035) and 93.7% of specificity (P = 0.0016). Non-psychotic prodromal symptoms bring valuable information to improve the prediction of conversion to psychosis. Elastic net logistic regression applied to clinical data is a promising way to switch from group prediction to an individualized prediction.

Clinical features of adolescents diagnosed with eating disorders and at risk for psychosis

BACKGROUND

The presence of subthreshold psychotic symptoms in adolescents with eating disorders is poorly described. This study provides a detailed characterization of adolescents affected by eating disorders in the absence or presence of subthreshold psychotic symptoms, taking into account a wide set of sociodemographic, psychological, and clinical variables.

METHODS

Ninety-four adolescents diagnosed with eating disorders were interviewed, focusing on clinical anamnesis and sociodemographic data collection. The Comprehensive Assessment of At-Risk Mental States (CAARMS) was used to assess the presence (HR+) or absence (HR-) of subthreshold psychosis. The clinicians completed a questionnaire on eating disorders severity, whereas patients provided self-report measures of global social functioning and psychological symptoms associated with eating disorders.

RESULTS

Attenuated psychotic symptoms were highly frequent (84% of subjects). HR+ patients experienced more frequently purging behaviors and dysmorphophobia and received a greater amount of antipsychotic drugs. Compared to HR- counterparts, HR+ patients reported higher eating disorders severity and psychological symptoms (i.e., ineffectiveness, interpersonal and affective problems) associated with eating disorders. Finally, a significant correlation between global social functioning and eating disorders severity emerged only for HR- subjects.

CONCLUSIONS

These descriptive data are warranted to identify a potential psychotic core in eating disorders, mainly concerning body image and weight as well as specific psychological features. The availability of reliable and valid markers of risk can further increase our capacity to detect the early emergence of psychosis in adolescents with eating disorders, whose outcome might be worsened by the presence of psychotic symptoms.

Clinical features of adolescents diagnosed with eating disorders and at risk for psychosis

BACKGROUND

The presence of subthreshold psychotic symptoms in adolescents with eating disorders is poorly described. This study provides a detailed characterization of adolescents affected by eating disorders in the absence or presence of subthreshold psychotic symptoms, taking into account a wide set of sociodemographic, psychological, and clinical variables.

METHODS

Ninety-four adolescents diagnosed with eating disorders were interviewed, focusing on clinical anamnesis and sociodemographic data collection. The Comprehensive Assessment of At-Risk Mental States (CAARMS) was used to assess the presence (HR+) or absence (HR-) of subthreshold psychosis. The clinicians completed a questionnaire on eating disorders severity, whereas patients provided self-report measures of global social functioning and psychological symptoms associated with eating disorders.

RESULTS

Attenuated psychotic symptoms were highly frequent (84% of subjects). HR+ patients experienced more frequently purging behaviors and dysmorphophobia and received a greater amount of antipsychotic drugs. Compared to HR- counterparts, HR+ patients reported higher eating disorders severity and psychological symptoms (i.e., ineffectiveness, interpersonal and affective problems) associated with eating disorders. Finally, a significant correlation between global social functioning and eating disorders severity emerged only for HR- subjects.

CONCLUSIONS

These descriptive data are warranted to identify a potential psychotic core in eating disorders, mainly concerning body image and weight as well as specific psychological features. The availability of reliable and valid markers of risk can further increase our capacity to detect the early emergence of psychosis in adolescents with eating disorders, whose outcome might be worsened by the presence of psychotic symptoms.

Interactions of immediate and long-term action regulation in the course and complications of bipolar disorder

Immediate and long-term mechanisms interact in the regulation of action. We will examine neurobiology and practical clinical consequences of these interactions. Long-term regulation of immediate behavioural control is based on analogous responses to highly rewarding or stressful stimuli: (i) impulsivity is a failure of the balance between activation and inhibition in the immediate regulation of action. (ii) Sensitization is a persistently exaggerated behavioural or physiological response to highly salient stimuli, such as addictive stimuli or inescapable stress. Sensitization can generalize across classes of stimuli. (iii) Impulsivity, possibly related to poor modulation of catecholaminergic and glutamatergic functions, may facilitate development of long-term sensitized responses to stressful or addictive stimuli. In turn, impulsivity is prominent in sensitized behaviour. (iv) While impulsivity and sensitization are general components of behaviour, their interactions are prominent in the course of bipolar disorder, emphasizing roles of substance-use, recurrent course and stressors. (v) Suicide is a complex and severe behaviour that exemplifies the manner in which impulsivity facilitates behavioural sensitization and is, in turn, increased by it, leading to inherently unpredictable behaviour. (vi) Interactions between impulsivity and sensitization can provide targets for complementary preventive and treatment strategies for severe immediate and long-term behavioural disorders. Progress along these lines will be facilitated by predictors of susceptibility to behavioural sensitization. This article is part of the theme issue 'Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications'.

Impulsivity and Suicidal Behavior

Suicide is the leading cause of injury mortality in the United States and the second-leading cause of death in people aged 10-34 years. While many long-term risk factors are known, the short-term prediction of suicidal behavior remains elusive. Many characteristics of suicidal behavior cut across diagnoses, but suicide is increased in recurrent psychiatric disorders, addictive disorders, and trauma-related disorders. Suicide results from the interaction of short-term and long-term behavioral regulation. The shorter the time-course of the mechanism, the closer it is to actual suicidal behavior, and the harder it is to prevent. We will discuss the manner in which impulsivity, a major determinant of short-term suicide risk, interacts with longer-term risk factors, especially sensitization to addictive or traumatic stimuli. Impulsivity predisposes to sensitization; in turn, impulsivity is a prominent component of sensitized behavior. Impulsivity can be described as a general pattern of behavior ("trait" impulsivity), as responses that are not conformed to their context (action-impulsivity), or as inability to delay reward or to take future consequences into account (choice-impulsivity). Each of these contributes to suicidal behavior. The neural mechanisms of impulsivity and sensitization are analogous, and sensitization can produce rapidly fluctuating patterns of impulsive behavior, arousal, and anhedonia. In order to recognize and prevent suicidal behavior, it is necessary to identify factors associated with susceptibility to bouts of impulsive behavior in people at elevated long-term risk.

Frontal cortical thickness correlates positively with impulsivity in early psychosis male patients

AIM

Impulsive behaviours, which are frequent in young people suffering from psychosis have been linked to risky and violent behaviours and participate to the burden of psychotic illness. Given that morphological brain correlates of impulsivity in schizophrenia have been poorly investigated especially in young adults, the aim of this study was to investigate the relationship between impulsivity and cortical thickness in early psychosis (EP) patients.

METHOD

A total of 17 male subjects in the early phase of psychosis were recruited. Impulsivity was assessed with the Lecrubier Impulsivity Rating Scale. Mean cortical thickness was extracted from magnetic resonance imaging brain scans, using surface-based methods.

RESULTS

Mean cortical thickness in the frontal lobe correlated positively with mean impulsivity in EP male patients.

CONCLUSION

Our results suggest that psychotic subjects exhibiting higher impulsivity have larger frontal cortical thickness, which may pave the way towards the identification of patients with a higher risk to display impulsive behaviours.

Brain structural abnormalities as potential markers for detecting individuals with ultra-high risk for psychosis: A systematic review and meta-analysis

OBJECTIVE

This study aims to determine whether structural alterations can be used as neuroimaging markers to detect individuals with ultra-high risk (UHR) for psychosis for the diagnosis of schizophrenia and improvement of treatment outcomes.

METHODS

Embase and Pubmed databases were searched for related studies in July 2018. The search was performed without restriction on time and regions or languages. A total of 188 articles on voxel-based morphometry (VBM) and 96 articles on cortical thickness were obtained, and another 6 articles were included after the reference lists were checked. Our researchers assessed and extracted the data in accordance with the PRISMA guideline. The data were processed with a seed-based mapping method.

RESULTS

Fourteen VBM and nine cortical thickness studies were finally included in our study. In individuals with UHR, the gray matter volumes in the bilateral median cingulate (Z = 1.034), the right fusiform gyrus (Z = 1.051), the left superior temporal gyrus (Z = 1.048), and the right thalamus (Z = 1.039) increased relative to those of healthy controls. By contrast, the gray matter volumes in the right gyrus rectus (Z = -2.109), the right superior frontal gyrus (Z = -2.321), and the left superior frontal gyrus (Z = -2.228) decreased. The robustness of these findings was verified through Jackknife sensitivity analysis, and heterogeneity across studies was low. Typically, cortical thickness alterations were not detected in individuals with UHR.

CONCLUSIONS

Structural abnormalities of the thalamocortical circuit may underpin the neurophysiology of psychosis and mark the vulnerability of transition to psychosis in UHR subjects.

Brain structure and trait impulsivity: A comparative VBM study contrasting neural correlates of traditional and alternative concepts in healthy subjects

Impulsivity as a trait modulates a range of cognitive functions, e.g. planning, decision-making, or response inhibition. Recent behavioural and psychometric findings challenge both the neurobiological models as well as the conceptualisation of psychometric measures of impulsivity. In the present study, we aimed to test the association of brain structure with the Barratt Impulsiveness Scale (BIS-11), a commonly applied self-rating instrument for impulsivity, using both the classical three-factor-model for impulsive behaviour (motor (IM), attentional (IA) and non-planning impulsivity (INP)), as well as the recently proposed alternative model contrasting inability to wait for reward (IWR) as an index of impulsive choice and rapid response style (RRS) as an index of impulsive action. We analysed brain structural data in a community sample of 85 healthy individuals, who completed the BIS-11, using voxel-based morphometry (CAT12: Computational Anatomy Toolbox 12). Regional volumes were correlated with the three traditional BIS-11 subscales, as well as IWR and RRS. BIS-11 total score was positively correlated with right inferior parietal, postcentral, and supramarginal grey matter (p < 0.05, FWE cluster-level corrected). Attentional impulsivity (IA) was also positively correlated with right inferior and superior parietal and supramarginal gyri. Comparison of the other scales did show some divergence, but most correlations did not survive correction for multiple comparisons. Our findings suggest that difference facets of trait impulsivity might be related to different brain areas, and might thus dissociate along distinct but overlapping neural networks. In contrast to lesion or patient studies, these analyses delineate physiological variance, and can thus help to conceptualise network models in the absence of pathology.

Volume of motor area predicts motor impulsivity

Impulsivity is a personality trait associated with many maladaptive behaviors. Trait impulsivity is typically divided into three different dimensions, including attentional impulsiveness, motor impulsiveness, and non-planning impulsiveness. In the present study, we examined the neuroanatomical basis of the multidimensional impulsivity trait. Eighty-four healthy participants were studied with structural magnetic resonance imaging. Multiple regression analyses revealed that the score of motor impulsiveness was negatively correlated with gray matter volumes of the right supplementary motor area and paracentral lobule. A machine-learning-based prediction analysis indicated that decreased gray matter volumes of the supplementary motor area and paracentral lobule strongly predicted the decrease in motor impulsiveness control. Our findings provide insights into the predictive role of motor brain structures in motor impulsivity and inhibition control.

Assessing the Relationship between Disordered Gamblers with Psychosis and Increased Gambling Severity: The Mediating Role of Impulsivity

OBJECTIVE

Recent research suggests that disordered gambling and psychosis co-occur at higher rates than expected in the general population. Gamblers with psychosis also report greater psychological distress and increased gambling severity. However, the mechanism by which psychosis leads to greater gambling symptomology remains unknown. The objective of the present research was to test whether impulsivity mediated the relationship between comorbid psychosis and gambling severity.

METHOD

The sample consisted of 394 disordered gamblers voluntarily seeking treatment at a large university hospital in São Paulo, Brazil. A semistructured clinical interview (Mini-International Neuropsychiatric Interview) was used to diagnosis the presence of psychosis by registered psychiatrists. Severity of gambling symptoms was assessed using the Gambling Symptom Assessment Scale, and the Barratt Impulsiveness Scale-11 provided a measure of impulsivity.

RESULTS

Of the sample, 7.2% met diagnostic criteria for psychosis. Individuals with a dual diagnosis of psychosis did not report greater gambling severity. Conversely, dual diagnoses of psychosis were associated with greater levels of impulsivity. Higher levels of impulsivity were also associated with greater gambling severity. Importantly, support for our hypothesised mediation model was found such that impulsivity mediated the association between disordered gambling and psychosis and gambling severity.

CONCLUSION

Impulsivity appears to be a transdiagnostic process that may be targeted in treatment among disordered gamblers with a dual diagnosis of psychosis to reduce problematic gambling behaviours.

Trait impulsiveness is related to smaller post-commissural putamen volumes in males but not females

Impulsivity is considered a vulnerability trait for addiction. Recently, we found trait non-planning impulsiveness measured with the Karolinska Scales of Personality was negatively correlated with dopamine D_2/3 receptor availability in the ventral striatum of healthy humans. While also observed in rodents, human studies have failed to find this association with other measures of trait impulsivity. We explored whether another rodent finding, reduced ventral striatum volume with greater impulsivity, could also be observed in humans using this scale. Non-planning impulsiveness was measured in 52 healthy subjects (21 female; mean age: 33.06 ± 9.69) using the Karolinska Scales of Personality. Striatal subregion volumes, including the globus pallidus, were acquired using the Multiple Automatically Generated Templates (MAGeT-Brain) algorithm. Although failing to support our a priori hypothesis, there was a significant sex interaction in the post-commissural putamen with impulsiveness. Exploratory analyses revealed impulsiveness was negatively correlated with post-commissural putamen volumes in males, but positively correlated in females. We replicated this finding in males in an increased sample (including all 52 previous subjects) who provided impulsiveness measured by the Temperament and Character Inventory (n = 73; 32 female; mean age: 33.48 ± 9.75). These correlations by sex were statistically different from one another, the main finding with the Kasolinksa Scales of Personality surviving correction for multiple comparisons. While impulsivity may be related to reduced ventral striatal D_2/3 receptors across sexes, males but not females may show significant reductions in post-commissural putamen volume. These findings have important implications for understanding biological markers underlying sex differences in drug addiction vulnerability.

Morphological connectivity correlates with trait impulsivity in healthy adults

Background

Impulsivity is one crucial personality trait associated with various maladaptive behavior and many mental disorders. In the study reported here, we investigated the relationship between impulsivity and morphological connectivity (MC) between human brain regions, a newly proposed measure for brain coordination through the development and learning.

Method

Twenty-four participants’ T1-weighted magnetic resonance imaging (MRI) images and their self-reported impulsivity scores, measured by the Barratt impulsiveness scale (BIS), were retrieved from the OpenfMRI project. First, we assessed the MC by quantifying the similarity of probability density function of local morphological features between the anterior cingulate cortex (ACC), one of the most crucial hubs in the neural network modulating cognitive control, and other association cortices in each participant. Then, we correlated the MC to impulsivity scores across participants.

Results

The BIS total score was found to correlate with the MCs between the ACC and two other brain regions in the right hemisphere: the inferior frontal gyrus (IFG), a well-established structure for inhibition control; the inferior temporal gyrus (ITG), which has been previously shown to be associated with hyperactive/impulsivity symptoms. Furthermore, the ACC-IFG MC was mainly correlated with motor impulsivity, and the ACC-ITG MC was mainly correlated with attentional impulsivity.

Discussion

Together, these findings provide evidence that the ACC, IFG, and ITG in the right hemisphere are involved neural networks modulating impulsivity. Also, the current findings highlight the utility of MC analyses in facilitating our understanding of neural correlates of behavioral and personality traits.

A schizophrenia relevant 5-Choice Serial Reaction Time Task for mice assessing broad monitoring, distractibility and impulsivity

The 5-Choice Serial Reaction Time Task (5-CSRTT) is an automated test for rodents allowing the assessment of multiple cognitive measures. Originally designed to assess cognitive deficits relevant to attention deficit hyperactivity disorder, it has been widely used in the investigation of neural systems of attention. In the current study, we have set up a modified version, which reduced the training phase to only 8-9 days with minimal food deprivation and without single-housing. Furthermore, based on evidence that patients with schizophrenia are more impaired in broad monitoring abilities than in sustained attention, we successfully developed a protocol replicating the Spatial Attentional Resource Allocation Task (SARAT), used in humans to assess broad monitoring. During this task, when the target appeared at a single pre-cued location, mice selectively responded faster. Instead, increasing the number of validly cued locations proportionately decreased accuracy. We then validated a protocol which is relevant for neuropsychiatric disorders in which additional irrelevant pre-cue lights selectively disrupted attention (distractibility). Finally, we improved previously used protocols changing inter-trial intervals from 5 to 7 s by randomly presenting this shift only in 20% of the trials. This resulted in a selective effect on premature responses (impulsivity), with important implications for schizophrenia as well as for other mental disorders. Therefore, this revised 5-CSRTT reduced training and stress on the animals while selectively measuring different cognitive functions with translational validity to schizophrenia and other psychiatric disorders.

Barratt Impulsivity in Healthy Adults Is Associated with Higher Gray Matter Concentration in the Parietal Occipital Cortex that Represents Peripheral Visual Field

Impulsivity is a personality trait of clinical importance. Extant research focuses on fronto-striatal mechanisms of impulsivity and how executive functions are compromised in impulsive individuals. Imaging studies employing voxel based morphometry highlighted impulsivity-related changes in gray matter concentrations in a wide array of cerebral structures. In particular, whereas prefrontal cortical areas appear to show structural alterations in individuals with a neuropsychiatric condition, the findings are less than consistent in the healthy population. Here, in a sample (n = 113) of young adults assessed for Barratt impulsivity, we controlled for age, gender and alcohol use, and showed that higher impulsivity score is associated with increased gray matter volume (GMV) in bilateral medial parietal and occipital cortices known to represent the peripheral visual field. When impulsivity components were assessed, we observed that this increase in parieto-occipital cortical volume is correlated with inattention and non-planning but not motor subscore. In a separate behavioral experiment of 10 young adults, we demonstrated that impulsive individuals are more vulnerable to the influence of a distractor on target detection in an attention task. If replicated, these findings together suggest aberrant visual attention as a neural correlate of an impulsive personality trait in neurotypical individuals and need to be reconciled with the literature that focuses on frontal dysfunctions.

Neural basis for inferring false beliefs and social emotions in others among individuals with schizophrenia and those at ultra-high risk for psychosis

Inferring beliefs and social emotions of others has different neural substrates and possibly different roles in the pathophysiology of different clinical phases of schizophrenia. The current study investigated the neural basis for inferring others' beliefs and social emotions, as individual concepts, in 17 subjects at ultra-high risk for psychosis (UHR), 16 patients with schizophrenia and 20 healthy controls. Brain activity significantly differed from normal in both the left superior temporal sulcus (STS) and the inferior frontal gyrus (IFG) in the schizophrenia group while inferring others' beliefs, whereas those of UHR group were in the middle of those in the schizophrenia and healthy-control groups. Brain activity during inferring others' social emotions significantly differed in both the left STS and right IFG among individuals at UHR; however, there was no significant difference in the schizophrenia group. In contrast, brain activity differed in the left IFG of those in both the schizophrenia and UHR groups while inferring social emotion. Regarding the difference in direction of the abnormality, both the UHR and schizophrenia groups were characterized by hyper-STS and hypo-IFG activations when inferring others' beliefs and emotions. These findings might reflect different aspects of the same pathophysiological process at different clinical phases of psychosis.

Paranoid thinking, cognitive bias and dangerous neighbourhoods: Implications for perception of threat and expectations of victimisation

BACKGROUND

Paranoid thinking is prevalent in the non-clinical population and cognitive mechanisms of heuristic reasoning and jumping to conclusions bias contributes to its formation and maintenance.

AIMS

This study investigated the degree to which paranoia, perceived environmental risk, heuristic reasoning and jumping to conclusions bias (measured with the beads task) contribute to misinterpretation of neutral stimuli, and whether this informed judgements regarding vulnerability to threat and crime. It is also investigated whether impulsiveness is a confounding factor on the beads task.

METHODS

Two hundred participants were recruited using a snowball-sampling method for a quantitative cross-sectional study. Participants reported demographic information, three psychometric questionnaires and two experimental tasks via an online paradigm hosted by the Bristol Online Survey tool.

RESULTS

Participants with high paranoia scores perceived their environment to be more dangerous than those with low scores. Participants with high paranoia scores also overestimated threat in neutral stimuli and had high expectations of future victimisation. Jumping to conclusions on the beads task did not predict fear of crime outcomes, but was predicted by impulsivity.

CONCLUSION

Participants who demonstrated paranoid thinking were more likely to reside in perceived dangerous neighbourhoods and overestimate threat. While this could indicate a paranoid heuristic, it is a potentially rational response to prior experiences of crime and victimisation. Implications and suggestions for future research are discussed.

Impulsivity is Associated with Increased Metabolism in the Fronto-Insular Network in Parkinson's Disease

Various neuroimaging studies demonstrated that the fronto-insular network is implicated in impulsive behavior. We compared glucose metabolism (as a proxy measure of neural activity) among 24 patients with Parkinson’s disease (PD) who presented with low or high levels of impulsivity based on the Barratt Impulsiveness Scale 11 (BIS) scores. Subjects underwent 18-fluorodeoxyglucose positron emission tomography (FDG-PET) and the voxel-wise group difference of FDG-metabolism was analyzed in Statistical Parametric Mapping (SPM8). Subsequently, we performed a partial correlation analysis between the FDG-metabolism and BIS scores, controlling for covariates (i.e., age, sex, severity of disease and levodopa equivalent daily doses). Voxel-wise group comparison revealed higher FDG-metabolism in the orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and right insula in patients with higher impulsivity scores. Moreover, there was a positive correlation between the FDG-metabolism and BIS scores. Our findings provide evidence that high impulsivity is associated with increased FDG-metabolism within the fronto-insular network in PD.

Cannabis use, schizotypy, and negative priming

The present study examined the effects of frequency of cannabis use, schizotypy, and age on cognitive control, as measured using a location-based negative priming task in a sample of 124 Australians aged 15-24 who had ever used cannabis. This study found that the schizotypy dimension of Impulsive Nonconformity had a significant effect on negative priming such that participants with higher scores on this dimension showed reduced negative priming. Also, higher levels of psychological distress were associated with greater negative priming. Finally, there was a significant age by cannabis use interaction indicating that younger, frequent users of cannabis may be more susceptible to its effects on cognitive control and perhaps at greater risk of developing a disorder on the psychosis dimension.

Post-error action control is neurobehaviorally modulated under conditions of constant speeded response

Post-error slowing (PES) is an error recovery strategy that contributes to action control, and occurs after errors in order to prevent future behavioral flaws. Error recovery often malfunctions in clinical populations, but the relationship between behavioral traits and recovery from error is unclear in healthy populations. The present study investigated the relationship between impulsivity and error recovery by simulating a speeded response situation using a Go/No-go paradigm that forced the participants to constantly make accelerated responses prior to stimuli disappearance (stimulus duration: 250 ms). Neural correlates of post-error processing were examined using event-related potentials (ERPs). Impulsivity traits were measured with self-report questionnaires (BIS-11, BIS/BAS). Behavioral results demonstrated that the commission error for No-go trials was 15%, but PES did not take place immediately. Delayed PES was negatively correlated with error rates and impulsivity traits, showing that response slowing was associated with reduced error rates and changed with impulsivity. Response-locked error ERPs were clearly observed for the error trials. Contrary to previous studies, error ERPs were not significantly related to PES. Stimulus-locked N2 was negatively correlated with PES and positively correlated with impulsivity traits at the second post-error Go trial: larger N2 activity was associated with greater PES and less impulsivity. In summary, under constant speeded conditions, error monitoring was dissociated from post-error action control, and PES did not occur quickly. Furthermore, PES and its neural correlate (N2) were modulated by impulsivity traits. These findings suggest that there may be clinical and practical efficacy of maintaining cognitive control of actions during error recovery under common daily environments that frequently evoke impulsive behaviors.