Cortical thickness correlates with impulsiveness in healthy adults

Dual-systems models of the genetic architecture of impulsive personality traits: neurogenetic evidence of distinct but related factors

BACKGROUND

Dual-systems models, positing an interaction between two distinct and competing systems (i.e. top-down self-control, and bottom-up reward- or emotion-based drive), provide a parsimonious framework for investigating the interplay between cortical and subcortical brain regions relevant to impulsive personality traits (IPTs) and their associations with psychopathology. Despite recent developments in multivariate analysis of genome-wide association studies (GWAS), molecular genetic investigations of these models have not been conducted.

METHODS

Using IPT GWAS, we conducted confirmatory genomic structural equation models (GenomicSEM) to empirically evaluate dual-systems models of the genetic architecture of IPTs. Genetic correlations between dual-systems factors and relevant cortical and subcortical neuroimaging phenotypes (regional/structural volume, cortical surface area, cortical thickness) were estimated and compared.

RESULTS

GenomicSEM dual-systems models underscored important sources of shared and unique genetic variance between top-down and bottom-up constructs. Specifically, a dual-systems genomic model consisting of sensation seeking and lack of self-control factors demonstrated distinct but related sources of genetic influences (rg = 0.60). Genetic correlation analyses provided evidence of differential associations between dual-systems factors and cortical neuroimaging phenotypes (e.g. lack of self-control negatively associated with cortical thickness, sensation seeking positively associated with cortical surface area). No significant associations were observed with subcortical phenotypes.

CONCLUSIONS

Dual-systems models of the genetic architecture of IPTs tested were consistent with study hypotheses, but associations with relevant neuroimaging phenotypes were mixed (e.g. no associations with subcortical volumes). Findings demonstrate the utility of dual-systems models for studying IPT genetic influences, but also highlight potential limitations as a framework for interpreting IPTs as endophenotypes for psychopathology.

Associations between behavioral and self-reported impulsivity, brain structure, and genetic influences in middle childhood

Impulsivity undergoes a normative developmental trajectory from childhood to adulthood and is thought to be driven by maturation of brain structure. However, few large-scale studies have assessed associations between impulsivity, brain structure, and genetic susceptibility in children. In 9112 children ages 9-10 from the ABCD study, we explored relationships among impulsivity (UPPS-P impulsive behavior scale; delay discounting), brain structure (cortical thickness (CT), cortical volume (CV), and cortical area (CA)), and polygenic scores for externalizing behavior (PGSEXT). Both higher UPPS-P total scores and more severe delay-discounting had widespread, low-magnitude associations with smaller CA in frontal and temporal regions. No associations were seen between impulsivity and CV or CT. Additionally, higher PGSEXT was associated with both higher UPPS-P scores and with smaller CA and CV in frontal and temporal regions, but in non-overlapping cortical regions, underscoring the complex interplay between genetics and brain structure in influencing impulsivity. These findings indicate that, within large-scale population data, CA is significantly yet weakly associated with each of these impulsivity measures and with polygenic risk for externalizing behaviors, but in distinct brain regions. Future work should longitudinally assess these associations through adolescence, and examine associated functional outcomes, such as future substance use and psychopathology.

Self-esteem and cortical thickness correlate with aggression in healthy children: A surface-based analysis

Aggressive behavior can have serious physical, psychological, and social consequences. However, little is known about the personality and neurological antecedents underlying aggressive behavior in children. The objective of this study was to investigate the relationship between self-esteem, aggression, and brain structure (i.e., cortical thickness and surface area) in a population of healthy children (N = 78; 9-12 years; mean age: 9.95 ± 0.90 years). The results revealed that self-esteem showed a negative association with aggression and significantly predicted aggressive behavior. No gender differences were found in aggression and its neural correlates. We performed the cortical parcellation method to further explore the neural foundations underlying the association of self-esteem with aggression. Children with higher aggression had increased cortical thickness in four clusters after multiple comparison correction: right medial orbitofrontal cortex, right lateral orbitofrontal cortex, right superior frontal gyrus, and left insula. In a mediation analysis, cortical thickness in the right medial orbitofrontal cortex contributed to the effect of self-esteem on aggression. These findings extend our understanding of morphological correlates of aggression in children, suggesting that an increased cortical thickness in childhood is a potential mechanism linking low self-esteem to aggression.

Persistence of effort in apathy

The syndrome of apathy has generated increasing interest in recent years as systematic evaluations have revealed its high prevalence and strong negative impact on quality of life across a wide range of neurological and psychiatric conditions. However, although several theoretical models have been proposed to account for various aspects of the condition, understanding of this syndrome is still incomplete. One influential model has proposed that apathy might be described as a quantitative reduction of goal-directed behaviour in comparison to an individual's prior level of functioning. Persistence of activity defined as the capacity to continue with a task - sometimes in the face of setbacks, high levels of difficulty or fatigue - is a crucial but understudied aspect of goal-directed behaviour. Surprisingly, it has not been investigated yet in the context of apathy. Here, we provide an overview of theoretical and experimental aspects of persistence in effort that might assist to develop methods for the investigation of persistence in human behaviour, particularly within the pathologic context of apathy.

Transdiagnostic brain correlates of self-reported trait impulsivity: A dimensional structure-symptom investigation

Impulsivity transcends psychiatric diagnoses and is often related to anhedonia. This ad hoc cross-sectional investigation explored 1) whether self-reported trait impulsivity mapped onto a common structural brain substrate across healthy controls (HCs) and psychiatric patients, and 2) in a more exploratory fashion, whether impulsivity and anhedonia were related to each other and shared overlapping brain correlates. Structural magnetic resonance imaging (sMRI) datasets from 234 participants including HCs (n = 109) and patients with opioid use disorder (OUD, n = 22), cocaine use disorder (CUD, n = 43), borderline personality disorder (BPD, n = 45) and schizophrenia (SZ, n = 15) were included. Trait impulsivity was measured with the Barratt Impulsiveness Scale (BIS-11) and anhedonia with a subscore of the Beck Depression Inventory (BDI). BIS-11 global score data were available for the entire sample, while data on the BIS-11 2nd order factors attentional, motor and non-planning were additionally in hand for a subsample consisting of HCs, OUD and BPD patients (n = 116). Voxel-based morphometry analyses were conducted for identifying dimensional associations between grey matter volume and impulsivity/anhedonia. Partial correlations were further performed to exploratory test the relationships between impulsivity and anhedonia and their corresponding volumetric brain substrates. Volume of the left opercular part of the inferior frontal gyrus (IFG) was negatively related to global impulsivity across the entire sample and specifically to motor impulsivity in the subsample of HCs, OUD and BPD patients. Across patients anhedonia expression was negatively correlated with left putamen volume. Although there was no relationship between global impulsivity and anhedonia across all patients, only across OUD and BPD patients anhedonia was positively associated with attentional impulsivity. Finally, also across OUD and BPD patients, motor impulsivity associated left IFG volume was positively linked with anhedonia-associated volume in the left putamen. Our findings suggest a critical role of left IFG volume in self-reported global impulsivity across healthy participants and patients with substance use disorder, BPD and SZ. Preliminary findings in OUD and BPD patients further suggests associations between impulsivity and anhedonia that are related to grey matter reductions in the left IFG and putamen.

Dual-systems models of the genetic architecture of impulsive personality traits: Neurogenetic evidence of distinct but related factors

Background

Dual-systems models provide a parsimonious framework for understanding the interplay between cortical and subcortical brain regions relevant to impulsive personality traits (IPTs) and their associations with psychiatric disorders. Despite recent developments in multivariate analysis of genome-wide association studies (GWAS), molecular genetic investigations of these models have not been conducted.

Methods

Using extant IPT GWAS, we conducted confirmatory genomic structural equation models (GenomicSEM) to empirically evaluate dual-systems models of the genetic architecture of IPTs. Genetic correlations between results of multivariate GWAS of dual-systems factors and GWAS of relevant cortical and subcortical neuroimaging phenotypes (regional/structural volume, cortical surface area, cortical thickness) were calculated and compared.

Results

Evaluation of GenomicSEM model fit indices for dual-systems models suggested that these models highlight important sources of shared and unique genetic variance between top-down and bottom-up constructs. Specifically, a dual-systems genomic model consisting of sensation seeking and lack of self-control factors demonstrated distinct but related sources of genetic influences ( r g =.60). Genetic correlation analyses provided evidence of differential associations between dual-systems factors and cortical neuroimaging phenotypes (e.g., lack of self-control negatively associated with cortical thickness, sensation seeking positively associated with cortical surface area). However, no significant associations were observed for subcortical phenotypes inconsistent with hypothesized functional localization of dual-systems constructs.

Conclusions

Dual-systems models of the genetic architecture of IPTs tested here demonstrate evidence of shared and unique genetic influences and associations with relevant neuroimaging phenotypes. These findings emphasize potential advantages in utilizing dual-systems models to study genetic influences for IPTs and transdiagnostic associations with psychiatric disorders.

Interindividual differences in intergenerational sustainable behavior are associated with cortical thickness of the dorsomedial and dorsolateral prefrontal cortex

Intergenerational sustainability requires people of the present generation to make sacrifices today to benefit others of future generations (e.g. mitigating climate change, reducing public debt). Individuals vary greatly in their intergenerational sustainability, and the cognitive and neural sources of these interindividual differences are not yet well understood. We here combined neuroscientific and behavioral methods by assessing interindividual differences in cortical thickness and by using a common-pool resource paradigm with intergenerational contingencies. This enabled us to look for objective, stable, and trait-like neural markers of interindividual differences in consequential intergenerational behavior. We found that individuals behaving sustainably (vs. unsustainably) were marked by greater cortical thickness of the dorsomedial and dorsolateral prefrontal cortex. Given that these brain areas are involved in perspective-taking and self-control and supported by mediation analyses, we speculate that greater cortical thickness of these brain areas better enable individuals to take the perspective of future generations and to resist temptations to maximize personal benefits that incur costs for future generations. By meeting recent calls for the contribution of neuroscience to sustainability research, it is our hope that the present study advances the transdisciplinary understanding of interindividual differences in intergenerational sustainability.

Overnight Abstinence Is Associated With Smaller Secondary Somatosensory Cortical Volumes and Higher Somatosensory-Motor Cortical Functional Connectivity in Cigarette Smokers

INTRODUCTION

Abstinence symptoms present challenges to successful cessation of cigarette smoking. Chronic exposure to nicotine and long-term nicotine abstinence are associated with alterations in cortical and subcortical gray matter volumes (GMVs).

AIMS AND METHODS

We aimed at examining changes in regional GMVs following overnight abstinence and how these regional functions relate to abstinence symptoms. Here, in a sample of 31 regular smokers scanned both in a satiety state and after overnight abstinence, we employed voxel-wise morphometry and resting-state functional connectivity (rsFC) to investigate these issues. We processed imaging data with published routines and evaluated the results with a corrected threshold.

RESULTS

Smokers showed smaller GMVs of the left ventral hippocampus and right secondary somatosensory cortex (SII) after overnight abstinence as compared to satiety. The GMV alterations in right SII were positively correlated with changes in withdrawal symptom severity between states. Furthermore, right SII rsFC with the precentral gyrus was stronger in abstinence as compared to satiety. The inter-regional rsFC was positively correlated with motor impulsivity and withdrawal symptom severity during abstinence and negatively with craving to smoke during satiety.

CONCLUSIONS

These findings highlight for the first time the effects of overnight abstinence on cerebral volumetrics and changes in functional connectivity of a higher-order sensory cortex. These changes may dispose smokers to impulsive behaviors and aggravate the urge to smoke at the earliest stage of withdrawal from nicotine.

IMPLICATIONS

Overnight abstinence leads to changes in gray matter volumes and functional connectivity of the second somatosensory cortex in cigarette smokers. Higher somatosensory and motor cortical connectivity in abstinence is significantly correlated with trait motor impulsivity and withdrawal symptom severity. The findings add to the literature of neural markers of nicotine addiction.

Empirical facts from search for replicable associations between cortical thickness and psychometric variables in healthy adults

The study of associations between inter-individual differences in brain structure and behaviour has a long history in psychology and neuroscience. Many associations between psychometric data, particularly intelligence and personality measures and local variations of brain structure have been reported. While the impact of such reported associations often goes beyond scientific communities, resonating in the public mind, their replicability is rarely evidenced. Previously, we have shown that associations between psychometric measures and estimates of grey matter volume (GMV) result in rarely replicated findings across large samples of healthy adults. However, the question remains if these observations are at least partly linked to the multidetermined nature of the variations in GMV, particularly within samples with wide age-range. Therefore, here we extended those evaluations and empirically investigated the replicability of associations of a broad range of psychometric variables and cortical thickness in a large cohort of healthy young adults. In line with our observations with GMV, our current analyses revealed low likelihood of significant associations and their rare replication across independent samples. We here discuss the implications of these findings within the context of accumulating evidence of the general poor replicability of structural-brain-behaviour associations, and more broadly of the replication crisis.

The Indirect Effect of Prefrontal Gray Matter Volume on Suicide Attempts among Individuals with Major Depressive Disorder

Trait impulsivity is a known risk factor for suicidality, and the prefrontal cortex plays a key role in impulsivity and its regulation. However, the relationship between trait impulsivity, neural basis, and suicidality has been inconsistent. Therefore, this study aimed to explore the relationship between impulsivity and its structural correlates (prefrontal gray matter volume), suicidal ideation, and actual suicide attempts. A total of 87 individuals with major depressive disorder participated in study, and the gray matter volume of the prefrontal regions was extracted from T1 images based on region of interest masks. The variables for the mediation models were selected based on correlation analysis and tested for their ability to predict suicide attempts, with impulsivity and suicidal ideation as the mediation variables and gray matter volume as the independent variable. A significant correlation was observed between suicidal ideation and the left dorsolateral prefrontal cortex and right dorsomedial prefrontal cortex. The dual-mediation model revealed a significant indirect relationship between gray matter volume in both regions and suicide attempts mediated by motor impulsivity and suicidal ideation. The counterintuitive positive relationship between gray matter volume and suicidality was also discussed.

Forgiveness Mediates the Relationship Between Middle Frontal Gyrus Volume and Clinical Symptoms in Adolescents

Dispositional forgiveness is positively associated with many facets of wellbeing and has protective implications against depression and anxiety in adolescents. However, little work has been done to examine neurobiological aspects of forgiveness as they relate to clinical symptoms. In order to better understand the neural mechanisms supporting the protective role of forgiveness in adolescents, the current study examined the middle frontal gyrus (MFG), which comprises the majority of the dorsolateral prefrontal cortex (DLPFC) and is associated with cognitive regulation, and its relationship to forgiveness and clinical symptoms in a sample of healthy adolescents. In this cross-sectional study (n = 64), larger MFG volume was significantly associated with higher self-reported dispositional forgiveness scores and lower levels of depressive and anxiety symptoms. Forgiveness mediated the relationship between MFG volume and both depressive and anxiety symptom levels. The mediating role of forgiveness in the relationship between MFG volume and clinical symptoms suggests that one way that cognitive regulation strategies supported by this brain region may improve adolescent mental health is via increasing a capacity for forgiveness. The present study highlights the relevance of forgiveness to neurobiology and their relevance to emotional health in adolescents. Future longitudinal studies should focus on the predictive quality of the relationship between forgiveness, brain volume and clinical symptoms and the effects of forgiveness interventions on these relationships.

Distinct clinical manifestations of obsessive-compulsive disorder are associated with cortical thickness alteration

BACKGROUND

Although brain structural changes have been reported in patients with obsessive-compulsive disorder (OCD), results from previous studies have been inconsistent. A growing number of studies have focused on obsessive beliefs and impulsivity which could be involved in the occurrence and maintenance of OCD symptoms. The present study aimed to examine whether there are distinct brain structural changes in patients with different OCD subgroups.

METHODS

Eighty-nine patients with OCD and 42 healthy controls were recruited to undergo structural magnetic resonance imaging brain scan. OCD patients were classified into subgroups according to scores of the Obsessive Belief Questionnaire (OBQ-44) and the Barratt Impulsiveness Scale (BIS-11) using cluster analysis. Group comparisons in cortical thickness and subcortical volumes between all OCD patients and healthy controls, as well as between subgroups of OCD patients and healthy controls, were carried out.

RESULTS

OCD patients with more obsessive beliefs and attentional impulsivity (OCD_OB_AT) had reduced cortical thickness at the inferior parietal gyrus, the superior and middle temporal gyrus and the insula compared with OCD patients with higher score on the non-planning impulsivity (OCD_NP, corrected p < 0.05). The whole group of OCD patients and both subgroups showed reduced cortical thickness at the superior parietal gyrus compared with controls (uncorrected p < 0.01, number of vertices > 100).

CONCLUSION

Our results suggest that apart from distinct phenomenology, there are distinct neural correlates of different OCD subgroups based on obsessive beliefs and impulsivity. These neural correlates may have clinical significance and should be considered in future research.

Relationship between impulsivity, uncontrolled eating and body mass index: a hierarchical model

BACKGROUND

Impulsivity increases the risk for obesity and weight gain. However, the precise role of impulsivity in the aetiology of overeating behavior and obesity is currently unknown. Here we examined the relationships between personality-related measures of impulsivity, Uncontrolled Eating, body mass index (BMI), and longitudinal weight changes. In addition, we analyzed the associations between general impulsivity domains and cortical thickness to elucidate brain vulnerability factors related to weight gain.

METHODS

Students (N = 2318) in their first year of university-a risky period for weight gain-completed questionnaire measures of impulsivity and eating behavior at the beginning of the school year. We also collected their weight at the end of the term (N = 1177). Impulsivity was divided into three factors: stress reactivity, reward sensitivity and lack of self-control. Using structural equation models, we tested a hierarchical relationship, in which impulsivity traits were associated with Uncontrolled Eating, which in turn predicted BMI and weight change. Seventy-one participants underwent T1-weighted MRI to investigate the correlation between impulsivity and cortical thickness.

RESULTS

Impulsivity traits showed positive correlations with Uncontrolled Eating. Higher scores in Uncontrolled Eating were in turn associated with higher BMI. None of the impulsivity-related measurements nor Uncontrolled Eating were correlated with longitudinal weight gain. Higher stress sensitivity was associated with increased cortical thickness in the superior temporal gyrus. Lack of self-control was positively associated with increased thickness in the superior medial frontal gyrus. Finally, higher reward sensitivity was associated with lower thickness in the inferior frontal gyrus.

CONCLUSION

The present study provides a comprehensive characterization of the relationships between different facets of impulsivity and obesity. We show that differences in impulsivity domains might be associated with BMI via Uncontrolled Eating. Our results might inform future clinical strategies aimed at fostering self-control abilities to prevent and/or treat unhealthy weight gain.

The Link Between Cannabis Use and Violent Behavior in the Early Phase of Psychosis: The Potential Role of Impulsivity

INTRODUCTION

Recently, the literature has shown that Cannabis Use (CU) was a risk factor for Violent Behavior (VB) in patients with psychosis, and those in the early phase of psychosis (EPP). These findings are relevant because of the high prevalence of CU in this EPP, and the potential for prevention during this phase of illness. However, there is still a lack of clear explanations, supported by empirical evidence, about what underlies the link between CU and VB against other.

METHOD

This viewpoint reviews the scientific literature on the link between CU and VB, and the involvement of impulsivity in this relationship. This last point will be addressed at clinical and neurobiological levels.

RESULTS

Recent studies confirmed that CU is particularly high in the EPP, and is a risk factor for VB in the EPP and schizophrenia. Studies have also shown that impulsivity is a risk factor for VB in psychosis, is associated with CU, and may mediate the link between CU and VB. Research suggests a neurobiological mechanism, as CU affects the structures and function of frontal areas, known to play a role in impulsive behavior.

CONCLUSION

Scientific evidence support the hypothesis of an involvement of impulsivity as a variable that could mediate the link between CU and aggression, particularly, when CU has an early onset. However, this hypothesis should be confirmed with longitudinal studies and by taking into account confounding factors. The studies highlight the relevance of early prevention in the EPP, in addition to interventions focusing on psychotic disorders.

Subcortical brain volume and cortical thickness in adolescent girls and women with binge eating

OBJECTIVE

Alterations in brain structure have been implicated in the onset and acute phases of several forms of psychopathology. However, there is a dearth of research investigating brain structure in persons with binge eating, contributing to poor understanding of mechanisms associated with binge eating.

METHOD

Adolescent girls and women (aged 14-35 years) with binge eating (n = 56) and group age-matched girls and women without binge eating (n = 26) completed structural magnetic resonance imaging (MRI) scans and interview-based and self-report assessments of eating disorder and general psychopathology. MRI data were processed using FreeSurfer. Analysis of covariance tested mean differences in subcortical volume and cortical thickness of a priori selected regions of interest between binge-eating and non-binge-eating groups, controlling for age, body mass index, purging frequency, depression, and medication use. Exploratory partial correlations tested associations between brain structure and eating disorder symptoms within participants with binge eating.

RESULTS

We did not observe differences in regional subcortical volume and cortical thickness between girls and women with and without binge eating. Within participants with binge eating, severity of attitudinal eating disorder symptoms was inversely associated with caudal middle frontal gyrus, right precentral gyrus, right postcentral gyrus, superior parietal, left inferior parietal thickness, and left accumbens volume; however, these associations would not survive multiple-comparison corrections.

DISCUSSION

Correlations between attitudinal eating disorder symptoms and frontoparietal thinning may represent a state marker of binge eating. Future research could investigate whether frontoparietal thinning worsens with illness duration or persists beyond binge eating cessation.

Association of Prefrontal Cortex Thinning with High Impulsivity in Healthy Adults

OBJECTIVE

Studies have been conducted to identify brain structural alterations related to high impulsivity in psychiatric populations. However, research on healthy subjects is relatively less extensive. Therefore, we aimed to investigate the correlation between the cortical thickness of whole brain regions and the impulsivity level in a healthy population.

METHODS

We included 100 healthy participants aged 19-65 years. Their T1-weighted magnetic resonance images and the 23-item Barratt Impulsiveness Scale (BIS) score were obtained. The patients were divided into high and low impulsivity groups according to the 75th percentile score of the BIS in the sample. The thickness of each cortical region was calculated using the FreeSurfer, and the difference in cortical thickness of the whole brain between the high and low impulsivity groups was analyzed using one-way analysis of covariance including age, sex, education level, and total intracranial cavity volume as covariates.

RESULTS

The high impulsivity group showed significant cortical thinning in the left pars opercularis. The cortical thickness of the left pars opercularis significantly correlated negatively with the total, attention, and motor scores of the BIS scale.

CONCLUSION

Our findings suggest that prefrontal cortex thinning may play an important role in the development of high impulsivity in healthy adults.

A Systematic Review of Obesity and Binge Eating Associated Impairment of the Cognitive Inhibition System

Altered functioning of the inhibition system and the resulting higher impulsivity are known to play a major role in overeating. Considering the great impact of disinhibited eating behavior on obesity onset and maintenance, this systematic review of the literature aims at identifying to what extent the brain inhibitory networks are impaired in individuals with obesity. It also aims at examining whether the presence of binge eating disorder leads to similar although steeper neural deterioration. We identified 12 studies that specifically assessed impulsivity during neuroimaging. We found a significant alteration of neural circuits primarily involving the frontal and limbic regions. Functional activity results show BMI-dependent hypoactivity of frontal regions during cognitive inhibition and either increased or decreased patterns of activity in several other brain regions, according to their respective role in inhibition processes. The presence of binge eating disorder results in further aggravation of those neural alterations. Connectivity results mainly report strengthened connectivity patterns across frontal, parietal, and limbic networks. Neuroimaging studies suggest significant impairment of various neural circuits involved in inhibition processes in individuals with obesity. The elaboration of accurate therapeutic neurocognitive interventions, however, requires further investigations, for a deeper identification and understanding of obesity-related alterations of the inhibition brain system.

Gray matter correlates of impulsivity in psychopathy and in the general population differ by kind, not by degree: a comparison of systematic reviews

A fundamental question in neuropsychiatry is whether a neurobiological continuum accompanies the behavioral continuum between subclinical and clinical traits. Impulsivity is a trait that varies in the general population and manifests severely in disorders like psychopathy. Is the neural profile of severe impulsivity in psychopathy an extreme but continuous manifestation of that associated with impulsivity in the general population (different by degree)? Or is it discontinuous and unique (different by kind)? Here, we compare systematic reviews of the relationship between impulsivity and gray matter in psychopathy and in the general population. The findings suggest that the neural profile associated with extreme impulsivity in psychopathy (increased gray matter in rostral and ventral striatum and prefrontal cortexes) is distinct from that associated with impulsivity in the general population (decreased gray matter in rostral and ventral prefrontal cortexes). Severe impulsivity in psychopathy may therefore arise from a pathophysiological mechanism that is unique to the disorder. These findings prompt the need for future studies to directly test the effect of group on the impulsivity–gray matter relationship in samples comprised of healthy individuals and individuals with psychopathy. The results caution against the use of community samples to examine impulsive psychopathic traits in relation to neurobiology.

Structural Brain Correlates of the Externalizing Spectrum in Young Adults

The externalizing spectrum, including traits and behaviors such as aggression, reduced inhibitiory control and substance abuse, is associated with altered prefrontal brain morphology. However, the degree to which different manifestations of the externalizing spectrum are associated with distinct or overlapping variations in individual brain morphology is unclear. Here, we therefore used structural magnetic resonance imaging, self-report assessment, and a response inhibition task in a sample of 59 young adults to examine how cortical thickness in the anterior cingulate cortex (ACC), orbitofrontal cortex (OFC), and dorsolateral prefrontal cortex (DLPFC) relate to four different manifestations of the externalizing spectrum: disinhibition, callous aggression, substance abuse, and behavioral inhibitory control. Using Bayesian linear regression models controlling for age, gender, and years of education, we found that the different manifestations of the externalizing spectrum were associated with both distinct and overlapping morphology variations. Specifically, both callous aggression and inhibitory control was associated with increased cortical thickness of the OFC, a region involved in reward processing, decision-making, and regulation of anxiety and fear. Both disinhibition and substance abuse were associated with DLPFC thickness, although with opposite association patterns, possibly reflecting processes related to inhibitory control, working memory and attention. Moreover, disinhibition, but not callous aggression or substance abuse, was associated with behavioral inhibitory control. Our results provide further support for the link between externalizing behaviors and prefrontal brain morphology, while identifying distinct prefrontal areas associated with different clinically relevant manifestations. These findings may help guide further research aimed at developing novel treatment and intervention strategies for externalizing behaviors and disorders.

Which came first: Cannabis use or deficits in impulse control?

Impulse control deficits are often found to co-occur with substance use disorders (SUDs). On the one hand, it is well known that chronic intake of drugs of abuse remodels the brain with significant consequences for a range of cognitive behaviors. On the other hand, individual variation in impulse control may contribute to differences in susceptibility to SUDs. Both of these relationships have been described, thus leading to a "chicken or the egg" debate which remains to be fully resolved. Does impulsivity precede drug use or does it manifest as a function of problematic drug usage? The link between impulsivity and SUDs has been most strongly established for cocaine and alcohol use disorders using both preclinical models and clinical data. Much less is known about the potential link between impulsivity and cannabis use disorder (CUD) or the directionality of this relationship. The initiation of cannabis use occurs most often during adolescence prior to the brain's maturation, which is recognized as a critical period of development. The long-term effects of chronic cannabis use on the brain and behavior have started to be explored. In this review we will summarize these observations, especially as they pertain to the relationship between impulsivity and CUD, from both a psychological and biological perspective. We will discuss impulsivity as a multi-dimensional construct and attempt to reconcile the results obtained across modalities. Finally, we will discuss possible avenues for future research with emerging longitudinal data.

Brain morphometric abnormalities in boys with attention-deficit/hyperactivity disorder revealed by sulcal pits-based analyses

AIM

Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder associated with widespread brain morphological abnormalities. Here, we utilized a sulcal pits-based method to provide new insight into the atypical cortical folding morphology in ADHD.

METHODS

Sulcal pits, the locally deepest points in each fold, were first extracted from magnetic resonance imaging data of 183 boys with ADHD (10.62 ± 1.96 years) and 167 age- and gender-matched typically developing controls (10.70 ± 1.73 years). Then, the geometrical properties of sulcal pits were statistically compared between ADHD and controls.

RESULTS

Our results demonstrated that the number of sulcal pits was reduced and confined to the superficial secondary sulci in the ADHD group relative to controls (P < .05). We also found that ADHD boys were associated with significantly increased pit depth in the left superior frontal junction, circular insular sulcus, right inferior frontal junction, and bilateral cingulate sulcus, as well as significantly decreased pit depth in the bilateral orbital sulcus (P < .05, corrected).

CONCLUSION

The experimental findings reveal atypical sulcal anatomy in boys with ADHD and support the feasibility of sulcal pits as anatomic landmarks for disease diagnosis.

Brain gray matter structures associated with trait impulsivity: A systematic review and voxel-based meta-analysis

Trait impulsivity is a multifaceted personality characteristic that contributes to maladaptive life outcomes. Although a growing body of neuroimaging studies have investigated the structural correlates of trait impulsivity, the findings remain highly inconsistent and heterogeneous. Herein, we performed a systematic review to depict an integrated delineation of gray matter (GM) substrates of trait impulsivity and a meta‐analysis to examine concurrence across previous whole‐brain voxel‐based morphometry studies. The systematic review summarized the diverse findings in GM morphometry in the past literature, and the quantitative meta‐analysis revealed impulsivity‐related volumetric GM alterations in prefrontal, temporal, and parietal cortices. In addition, we identified the modulatory effects of age and gender in impulsivity‐GM volume associations. The present study advances understanding of brain GM morphometry features underlying trait impulsivity. The findings may have practical implications in the clinical diagnosis of and intervention for impulsivity‐related disorders.

Psychosocial Intervention for Youth With High Externalizing Behaviors and Aggression Is Associated With Improvement in Impulsivity and Brain Gray Matter Volume Changes

Background: Stop, Now And Plan (SNAP) is a cognitive behavioral-based psychosocial intervention that has a strong evidence base for treating youth with high aggression and externalizing behaviors, many of whom have disruptive behavior disorders. In a pre-post design, we tested whether SNAP could improve externalizing behaviors, assessed by the parent-rated Child Behavior Checklist (CBCL) and also improve behavioral measures of impulsivity in children with high aggression and impulsivity. We then investigated whether any improvement in externalizing behavior or impulsivity was associated with gray matter volume (GMV) changes assessed using structural magnetic resonance imaging (sMRI). We also recruited typically developing youth who were assessed twice without undergoing the SNAP intervention. Methods: Ten children who were participating in SNAP treatment completed the entire study protocol. CBCL measures, behavioral measures of impulsivity, and sMRI scanning was conducted pre-SNAP and then 13 weeks later post-SNAP. Twelve healthy controls also completed the study; they were rated on the CBCL, performed the same behavioral measure of impulsivity, and underwent sMRI twice, separated by 13 weeks. They did not receive the SNAP intervention. Result: At baseline, SNAP participants had higher CBCL scores and performed worse on the impulsivity task compared with the healthy controls. At the second visit, SNAP participants still had higher scores on the CBCL compared with normally-developing controls, but their performance on the impulsivity task had improved to the point where their results were indistinguishable from the healthy controls. Structural magnetic resonance imaging in the SNAP participants further revealed that improvements in impulsivity were associated with GMV changes in the frontotemporal region. Conclusion: These results suggest that SNAP led to improvement in behavioral measures of impulsivity in a cohort of boys with high externalizing behavior. Improvement in impulsivity was also associated with increased GMV changes. The mechanism behind these brain changes is unknown but could relate to cognitive behavioral therapy and contingency management interventions, important components of SNAP, that target frontotemporal brain regions. Clinically, this study offers new evidence for the potential targeting of brain regions by non-invasive modalities, such as repetitive transcranial magnetic stimulation, to improve externalizing behavior and impulsivity.

Neural bases of inhibitory control: Combining transcranial magnetic stimulation and magnetic resonance imaging in alcohol-use disorder patients

Inhibitory control underlies the ability to inhibit inappropriate responses and involves processes that suppress motor excitability. Such motor modulatory effect has been largely described during action preparation but very little is known about the neural circuit responsible for its implementation. Here, we addressed this point by studying the degree to which the extent of preparatory suppression relates to brain morphometry. We investigated this relationship in patients suffering from severe alcohol use disorder (AUD) because this population displays an inconsistent level of preparatory suppression and major structural brain damage, making it a suitable sample to measure such link. To do so, 45 detoxified patients underwent a structural magnetic resonance imaging (MRI) and performed a transcranial magnetic stimulation (TMS) experiment, in which the degree of preparatory suppression was quantified. Besides, behavioral inhibition and trait impulsivity were evaluated in all participants. Overall, whole-brain analyses revealed that a weaker preparatory suppression was associated with a decrease in cortical thickness of a medial prefrontal cluster, encompassing parts of the anterior cingulate cortex and superior-frontal gyrus. In addition, a negative association was observed between the thickness of the supplementary area (SMA)/pre-SMA and behavioral inhibition abilities. Finally, we did not find any significant correlation between preparatory suppression, behavioral inhibition and trait impulsivity, indicating that they represent different facets of inhibitory control. Altogether, the current study provides important insight on the neural regions underlying preparatory suppression and allows highlighting that the excitability of the motor system represents a valuable read-out of upstream cognitive processes.

Interactive effects of gender and sexual orientation on cortical thickness, surface area and gray matter volume: a structural brain MRI study

Background

Testosterone is thought to play a crucial role in sexual differentiation of the brain, and sexual orientation is programmed into our brain structures even when we are still fetuses. Although gender and sexual orientation differences have been shown respectively in many brain structures, the mechanism underlying the sexual differentiation of the brain is still unknown. The study is to investigate the interactive effects of gender and sexual orientation on cerebral structures in homosexual and heterosexual people.

Methods

Sexual orientation was evaluated by the Kinsey scale. We collected structural magnetic resonance image (MRI) data of local cortical thickness, surface area, and gray matter volume in all the subjects (29 homosexual and 29 heterosexual men, 17 homosexual and 17 heterosexual women). Statistical maps were generated using a general linear model (GLM) using FreeSurfer's Query, Design, Estimate, Contrast (QDEC) interface. We had sexual orientation and gender as 2 discrete factors with 2 levels, allowing for the generation of the interaction between sexual orientation and gender: homosexual women and heterosexual men versus heterosexual women and homosexual men. Coordinates were in Talairach space. All the cluster sizes were calculated with a P value of 0.01.

Results

Results revealed interactions concerning the area and gray matter volume between the factors of sexual orientation and gender. Regarding the thickness, an interaction was not found in any regions of the clusters. Regarding the area, an interaction was found in region of left middle temporal lobe, inferior temporal lobe, lateral occipital lobe, fusiform [(-58.1, -38.6, -14.7), maximum vertex-wise (MV) log₁₀(P) =3.30, cluster size (CS) =1,286.90 mm²], and left rostral middle frontal lobe, pars opercularis, caudal middle frontal lobe [(-37.3, 23.6, 24.8), MV log₁₀(P) =2.92, CS =1,194.40 mm²]. Regarding the gray matter volume, an interaction was found in the region of the left pars opercularis (inferior frontal gyrus) [(-42.9, 6.3, 18.5), MV log₁₀(P) =1.31, CS =526.79 mm²].

Conclusions

The present study extends our understandings of how structural features differ in homosexual men, heterosexual men, homosexual women, and heterosexual women. Furthermore, it highlights the interactions between sexual orientation and gender in the left inferior frontal gyrus, bilateral temporal lobe, and the right rostral anterior cingulate cortex, which are suggested to play a critical role in the sexual differentiation of the human brain.

Influence of Gonadotropin Hormone Releasing Hormone Agonists on Interhemispheric Functional Connectivity in Girls With Idiopathic Central Precocious Puberty

Purpose: The pubertal growth suppressive effects of gonadotropin hormone releasing hormone agonists (GnRHa) are well-known, although it remains unclear if long-term GnRHa treatment influences the brain function of treated children. The present study investigated the differences in the homotopic resting-state functional connectivity patterns in girls with idiopathic central precocious puberty (ICPP) with and without GnRHa treatment using voxel-mirrored homotopic connectivity (VMHC).

Methods: Eighteen girls with ICPP who underwent 12 months of GnRHa treatment, 40 treatment-naïve girls with ICPP, and 19 age-matched girls with premature thelarche underwent resting-state functional magnetic resonance imaging using a 3T MRI. VMHC method was performed to explore the differences in the resting-state interhemispheric functional connectivity. The levels of serum pubertal hormones, including luteinizing hormone (LH), follicular-stimulating hormone, and estradiol, were assessed. Correlation analyses among the results of clinical laboratory examinations, neuropsychological scales, and VMHC values of different brain regions were performed with the data of the GnRHa treated group.

Results: Significant decreases in VMHC of the lingual, calcarine, superior temporal, and middle frontal gyri were identified in the untreated group, compared with the control group. Medicated patients showed decreased VMHC in the superior temporal gyrus, when compared with the controls. Compared to the unmedicated group, the medicated group showed a significant increase in VMHC in the calcarine and middle occipital gyrus. Moreover, a positive correlation was observed between basal LH levels and VMHC of the middle occipital gyrus in medicated patients.

Conclusions: These findings indicate that long-term treatment with GnRHa was associated with increased interhemispheric functional connectivity within several areas responsible for memory and visual process in patients with ICPP. Higher interhemispheric functional connectivity in the middle occipital gyrus was related to higher basal LH production in the girls who underwent treatment. The present study adds to the growing body of research associated with the effects of GnRHa on brain function.

Linking personality and brain anatomy: a structural MRI approach to Reinforcement Sensitivity Theory

Reinforcement Sensitivity Theory (RST) proposes a widely used taxonomy of human personality linked to individual differences at both behavioral and neuropsychological levels that describe a predisposition to psychopathology. However, the body of RST research was based on animal findings, and little is known about their anatomical correspondence in humans. Here we set out to investigate MRI structural correlates (i.e. voxel-based morphometry) of the main personality dimensions proposed by the RST in a group of 400 healthy young adults who completed the Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ). Sensitivity to punishment scores correlated positively with the gray matter volume in the amygdala, whereas sensitivity to reward scores correlated negatively with the volume in the left lateral and medial prefrontal cortex. Moreover, a negative relationship was found between the striatal volume and the reward sensitivity trait, but only for male participants. The present results support the neuropsychological basis of the RST by linking punishment and reward sensitivity to anatomical differences in limbic and frontostriatal regions, respectively. These results are interpreted based on previous literature related to externalizing and internalizing disorders, and they highlight the possible role of SPSRQ as a measure of proneness to these disorders.

Altered Brain Structure and Functional Connectivity Associated with Pubertal Hormones in Girls with Precocious Puberty

Pubertal hormones play an important role in brain and psychosocial development. However, the role of abnormal HPG axis states in altering brain function and structure remains unclear. The present study is aimed at determining whether there were significant differences in gray matter volume (GMV) and resting state (RS) functional connectivity (FC) patterns in girls with idiopathic central precocious puberty (CPP) and peripheral precocious puberty (PPP). We further explored the correlation between these differences and serum pubertal hormone levels. To assess this, we recruited 29 idiopathic CPP girls and 38 age-matched PPP girls. A gonadotropin-releasing hormone (GnRH) stimulation test was performed, and pubertal hormone levels (including luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), prolactin, and cortisol) were assessed. All subjects underwent multimodal magnetic resonance imaging of brain structure and function. Voxel-based morphometry (VBM) analysis was paired with seed-to-voxel whole-brain RS-FC analysis to calculate the GMV and RS-FC in idiopathic CPP and PPP girls. Correlation analyses were used to assess the effects of pubertal hormones on brain regions with structural and functional differences between the groups. We found that girls with CPP exhibited decreased GMV in the left insula and left fusiform gyrus, while connectivity between the left and right insula and the right middle frontal gyrus (MFG), as well as the left fusiform gyrus and right amygdala, was reduced in girls with CPP. Furthermore, the GMV of the left insula and peak FSH levels were negatively correlated while higher basal and peak E2 levels were associated with increased bilateral insula RS-FC. These findings suggest that premature activation of the HPG axis and pubertal hormone fluctuations alter brain structure and function involved in the cognitive and emotional process in early childhood. These findings provide vital insights into the early pathophysiology of idiopathic CPP.

Cortical Thickness Links Impulsive Personality Traits and Risky Behavior

Impulsive personality traits are often predictive of risky behavior, but not much is known about the neurobiological basis of this relationship. We investigated whether thickness of the cortical mantle varied as a function of impulsive traits and whether such variation also explained recent risky behavior. A community sample of 107 adults (ages 18–55; 54.2% men) completed self-report measures of impulsive traits and risky behavior followed by a neuroimaging protocol. Using the three-factor model of impulsive traits derived from the UPPS-P Impulsive Behavior Scale, analysis of the entire cortical mantle identified three thickness clusters that related to impulsive traits. Sensation seeking was negatively related to thickness in the right pericalcarine cortex, whereas impulsive urgency was positively associated with thickness in the left superior parietal and right paracentral lobule. Notably, follow-up analyses showed that thickness in the right pericalcarine cortex also related to recent risky behavior, with the identified cluster mediating the association between sensation seeking and risky behavior. Findings suggest that reduced thickness in the pericalcarine region partially explains the link between sensation seeking and the tendency to engage in risky behavior, providing new insight into the neurobiological basis of these relationships.

Cortical Contributions to Distinct Symptom Dimensions of Catatonia

Catatonia is a central aspect of schizophrenia spectrum disorders (SSD) and most likely associated with abnormalities in affective, motor, and sensorimotor brain regions. However, contributions of different cortical features to the pathophysiology of catatonia in SSD are poorly understood. Here, T1-weighted structural magnetic resonance imaging data at 3 T were obtained from 56 right-handed patients with SSD. Using FreeSurfer version 6.0, we calculated cortical thickness, area, and local gyrification index (LGI). Catatonic symptoms were examined on the Northoff catatonia rating scale (NCRS). Patients with catatonia (NCRS total score ≥3; n = 25) showed reduced surface area in the parietal and medial orbitofrontal gyrus and LGI in the temporal gyrus (P < .05, corrected for cluster-wise probability [CWP]) as well as hypergyrification in rostral cingulate and medial orbitofrontal gyrus when compared with patients without catatonia (n = 22; P < .05, corrected for CWP). Following a dimensional approach, a negative association between NCRS motor and behavior scores and cortical thickness in superior frontal, insular, and precentral cortex was found (34 patients with at least 1 motor and at least 1 other affective or behavioral symptom; P < .05, corrected for CWP). Positive associations were found between NCRS motor and behavior scores and surface area and LGI in superior frontal, posterior cingulate, precentral, and pericalcarine gyrus (P < .05, corrected for CWP). The data support the notion that cortical features of distinct evolutionary and genetic origin differently contribute to catatonia in SSD. Catatonia in SSD may be essentially driven by cortex variations in frontoparietal regions including regions implicated in the coordination and goal-orientation of behavior.

The Effect of Mindfulness Meditation on Impulsivity and its Neurobiological Correlates in Healthy Adults

Interest has grown in using mindfulness meditation to treat conditions featuring excessive impulsivity. However, while prior studies find that mindfulness practice can improve attention, it remains unclear whether it improves other cognitive faculties whose deficiency can contribute to impulsivity. Here, an eight-week mindfulness intervention did not reduce impulsivity on the go/no-go task or Barratt Impulsiveness Scale (BIS-11), nor produce changes in neural correlates of impulsivity (i.e. frontostriatal gray matter, functional connectivity, and dopamine levels) compared to active or wait-list control groups. Separately, long-term meditators (LTMs) did not perform differently than meditation-naïve participants (MNPs) on the go/no-go task. However, LTMs self-reported lower attentional impulsivity, but higher motor and non-planning impulsivity on the BIS-11 than MNPs. LTMs had less striatal gray matter, greater cortico-striatal-thalamic functional connectivity, and lower spontaneous eye-blink rate (a physiological dopamine indicator) than MNPs. LTM total lifetime practice hours (TLPH) did not significantly relate to impulsivity or neurobiological metrics. Findings suggest that neither short- nor long-term mindfulness practice may be effective for redressing impulsive behavior derived from inhibitory motor control or planning capacity deficits in healthy adults. Given the absence of TLPH relationships to impulsivity or neurobiological metrics, differences between LTMs and MNPs may be attributable to pre-existing differences.

Future Directions for Personality Research: Contributing New Insights to the Understanding of Animal Behavior

As part of the European Conference on Behavioral Biology 2018, we organized a symposium entitled, "Animal personality: providing new insights into behavior?" The aims of this symposium were to address current research in the personality field, spanning both behavioral ecology and psychology, to highlight the future directions for this research, and to consider whether differential approaches to studying behavior contribute something new to the understanding of animal behavior. In this paper, we discuss the study of endocrinology and ontogeny in understanding how behavioral variation is generated and maintained, despite selection pressures assumed to reduce this variation. We consider the potential mechanisms that could link certain traits to fitness outcomes through longevity and cognition. We also address the role of individual differences in stress coping, mortality, and health risk, and how the study of these relationships could be applied to improve animal welfare. From the insights provided by these topics, we assert that studying individual differences through the lens of personality has provided new directions in behavioral research, and we encourage further research in these directions, across this interdisciplinary field.

Differentiation between young adult Internet addicts, smokers, and healthy controls by the interaction between impulsivity and temporal lobe thickness

BACKGROUND AND AIMS

Internet addiction is a non-substance-related addiction disorder with progressively growing prevalence. Internet addiction, like substance-related addictions, has been linked with high impulsivity, low inhibitory control, and poor decision-making abilities. Cortical thickness measurements and trait impulsivity have been shown to have a distinct relationship in addicts compared to healthy controls. Thus, we test whether the cortical correlates of trait impulsivity are different in Internet addicts and healthy controls, using an impulsive control group (smokers).

METHODS

Thirty Internet addicts (15 females) and 60 age- and gender-matched controls (30 smokers, all young adults aged 19-28 years) were scanned using a 3T MRI scanner and completed the Barratt Impulsiveness Scale.

RESULTS

Internet addicts had a thinner left superior temporal cortex than controls. Impulsivity had a significant main effect on the left pars orbitalis and bilateral insula, regardless of group membership. We identified divergent relationships between trait impulsivity and thicknesses of the bilateral middle temporal, right superior temporal, left inferior temporal, and left transverse temporal cortices between Internet addicts and healthy controls. Further analysis with smokers revealed that the left middle temporal and left transverse temporal cortical thickness change might be exclusive to Internet addiction.

DISCUSSION

The effects of impulsivity, combined with a long-term exposure to some specific substance or stimuli, might result in different natures of relationships between impulsivity and brain structure when compared to healthy controls.

CONCLUSION

These results may indicate that Internet addiction is similar to substance-related addictions, such that inefficient self-control could result in maladaptive behavior and inability to resist Internet use.

Regional Homogeneity Abnormalities in Early-Onset and Adolescent-Onset Conduct Disorder in Boys: A Resting-State fMRI Study

Purpose: Developmental taxonomic theory posits that formation of early-onset conduct disorder (EO-CD), is considered to have a neurodevelopmental etiology and have more severe psychosocial and neuropsychological dysfunction than adolescent-onset CD (AO-CD), which is thought to stem largely from social mimicry of deviant peers. The purpose of the current study was to investigate whether regional homogeneity (ReHo), denoting the spontaneous brain activity, supports developmental taxonomic theory in a resting state (rs).

Materials and Methods: Rs-functional magnetic resonance imaging (fMRI) examinations were administered to 36 EO-CD patients, 32 AO-CD patients, and 30 healthy controls (HCs). All participants were male adolescents, aged between 12 and 17 years old. A one-way analysis of covariance (ANCOVA), with age and IQ as covariates, was performed to identify regions with significant group differences in ReHo values, followed by a post hoc analyses.

Results: Compared with the AO-CD groups, EO-CD had higher ReHo values in the right middle/inferior frontal gyrus. Compared with the HCs, the EO-CD group exhibited lower ReHo values in the left precuneus, left middle occipital gyrus, left cerebellum posterior lobe and the right inferior parietal lobule, as well as higher ReHo values in the right middle frontal gyrus, left insula/inferior frontal gyrus, right postcentral gyrus, and the left anterior cingulate gyrus. Compared with the HCs, the AO-CD group showed lower ReHo values in the bilateral precuneus, left cerebellum posterior lobe, and the right inferior parietal lobule.

Conclusion: Significant differences in ReHo were observed between the EO-CD and AO-CD groups, implying distinct neuropathological mechanisms of the two CD subtypes, consistent with developmental taxonomic theory. CD-associated abnormalities in ReHo may be related to high-order cognitive and low-level perceptual system impairments in CD.

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.

Decreased olfactory discrimination is associated with impulsivity in healthy volunteers

In clinical populations, olfactory abilities parallel executive function, implicating shared neuroanatomical substrates within the ventral prefrontal cortex. In healthy individuals, the relationship between olfaction and personality traits or certain cognitive and behavioural characteristics remains unexplored. We therefore tested if olfactory function is associated with trait and behavioural impulsivity in nonclinical individuals. Eighty-three healthy volunteers (50 females) underwent quantitative assessment of olfactory function (odour detection threshold, discrimination, and identification). Each participant was rated for trait impulsivity index using the Barratt Impulsiveness Scale and performed a battery of tasks to assess behavioural impulsivity (Stop Signal Task, SST; Information Sampling Task, IST; Delay Discounting). Lower odour discrimination predicted high ratings in non-planning impulsivity (Barratt Non-Planning impulsivity subscale); both, lower odour discrimination and detection threshold predicted low inhibitory control (SST; increased motor impulsivity). These findings extend clinical observations to support the hypothesis that deficits in olfactory ability are linked to impulsive tendencies within the healthy population. In particular, the relationship between olfactory abilities and behavioural inhibitory control (in the SST) reinforces evidence for functional overlap between neural networks involved in both processes. These findings may usefully inform the stratification of people at risk of impulse-control-related problems and support planning early clinical interventions.

Does Family History of Alcohol Use Disorder Relate to Differences in Regional Brain Volumes? A Descriptive Review with New Data

BACKGROUND

Differences in regional brain volumes as a function of family history (FH) of alcohol use disorder (AUD) have been reported, and it has been suggested that these differences might index genetic risk for AUD. However, results have been inconsistent. The aims of the current study were (i) to provide an updated descriptive review of the existing literature and (ii) to examine the association of FH with indices of subcortical volumes and cortical thickness in a sample of youth recruited based on FH status.

METHODS

To address aim 1, a literature search located 15 published studies comprising 1,735 participants. Studies were characterized according to population, analytic methods, regions of interest, and primary findings. To address the second aim, we examined volumetric and cortical thickness in a sample of 69 youth (mean age = 19.71 years, SD = 0.79) recruited based on FH status and matched on drinking variables. Associations of sex and alcohol use with volumetric outcomes were also examined.

RESULTS

Our descriptive review revealed an inconsistent pattern of results with respect to the presence, direction, and regional specificity of volumetric differences across FH groups. The most consistent finding, significantly smaller amygdala volumes in FH+ participants, was not replicated in all studies. In the current sample of youth, measures of subcortical volumes and cortical thickness did not significantly differ as a function of FH, sex, or their interaction.

CONCLUSIONS

Evidence for FH group differences in regional brain volumes is inconsistent, and the current study failed to detect any group differences. Further research is needed to confirm the reproducibility of FH group differences and implications for AUD risk.

Anxiety, depression, impulsivity, and brain structure in children and adolescents

The unique neuroanatomical underpinnings of internalizing symptoms and impulsivity during childhood are not well understood. In this study, we examined associations of brain structure with anxiety, depression, and impulsivity in children and adolescents. Participants were 7- to 21-year-olds (N = 328) from the Pediatric Imaging, Neurocognition, and Genetics (PING) study who completed high-resolution, 3-Tesla, T1-weighted MRI and self-report measures of anxiety, depression, and/or impulsivity. Cortical thickness and surface area were examined across cortical regions-of-interest (ROIs), and exploratory whole-brain analyses were also conducted. Gray matter volume (GMV) was examined in subcortical ROIs. When considered separately, higher depressive symptoms and impulsivity were each significantly associated with reduced cortical thickness in ventromedial PFC/medial OFC, but when considered simultaneously, only depressive symptoms remained significant. Higher impulsivity, but not depressive symptoms, was associated with reduced cortical thickness in the frontal pole, rostral middle frontal gyrus, and pars orbitalis. No differences were found for regional surface area. Higher depressive symptoms, but not impulsivity, were significantly associated with smaller hippocampal GMV and larger pallidal GMV. There were no significant associations between anxiety symptoms and brain structure. Depressive symptoms and impulsivity may be linked with cortical thinning in overlapping and distinct regions during childhood and adolescence.

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Internalizing problems and impulsivity may have shared and distinct neuroanatomical substrates in childhood.

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Higher depressive symptoms were uniquely associated with reduced cortical thickness in vmPFC/medial OFC.

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Higher impulsivity was uniquely associated with reduced cortical thickness in lateral PFC regions.

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Higher depressive symptoms were associated with smaller hippocampal volume and larger pallidal volume.

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These shared and distinct neuroanatomical correlates may inform the design of prevention and intervention strategies.

The relationship of impulsivity and cortical thickness in depressed and non-depressed adolescents

Major Depressive Disorder (MDD) is recognized to be heterogeneous in terms of brain structure abnormality findings across studies, which might reflect previously unstudied traits that confer variability to neuroimaging measurements. The purpose of this study was to examine the relationships between different types of trait impulsivity and MDD diagnosis on adolescent brain structure. We predicted that adolescents with depression who were high on trait impulsivity would have more abnormal cortical structure than depressed patients or non-MDD who were low on impulsivity. We recruited 58 subjects, including 29 adolescents (ages 12-19) with a primary DSM-IV diagnosis of MDD and a history of suicide attempt and 29 demographically-matched healthy control participants. Our GLM-based analyses sought to describe differences in the linear relationships between cortical thickness and impulsivity trait levels. As hypothesized, we found significant moderation effects in rostral middle frontal gyrus and right paracentral lobule cortical thickness for different subscales of the Barratt Impulsiveness Scale. However, although these brain-behavior relationships differed between diagnostic study groups, they were not simple additive effects as we had predicted. For the middle frontal gyrus, non-MDD participants showed a strong positive association between cortical thickness and BIS-11 Motor scores, while MDD-diagnosed participants showed a negative association. For Non-Planning Impulsiveness, paracentral lobule cortical thickness was observed with greater impulsivity in MDD, but no association was found for controls. In conclusion, the findings confirm that dimensions of impulsivity have discrete neural correlates, and show that relationships between impulsivity and brain structure are expressed differently in adolescents with MDD compared to non-MDD.

Neuroanatomical correlates of grit: Growth mindset mediates the association between gray matter structure and trait grit in late adolescence

There is a long-standing interest in exploring the factors related to student achievement. As a newly explored personality trait, grit is defined as a person's tendency to pursue long-term goals with continual perseverance and passion, and grit plays a critical role in student achievement. Increasing evidence has shown that growth mindset, the belief that one's basic abilities are malleable and can be developed through effort, is a potential factor for cultivating grit. However, less is known about the association between grit and the brain and the role of growth mindset in this association. Here, we utilized voxel-based morphometry to examine the neuroanatomical correlates of grit in 231 healthy adolescent students by performing structural magnetic resonance imaging. The whole-brain regression analyses revealed that the regional gray matter volume (rGMV) in the left dorsolateral prefrontal cortex (DLPFC) negatively predicted grit. In contrast, the rGMV in the right putamen positively predicted grit. Furthermore, mediating analyses suggested that growth mindset served as a mediator in the association between left DLPFC volume and grit. Our results persisted even after controlling for the influences of self-control and delayed gratification. Overall, our study presents novel evidence for the neuroanatomical basis of grit and highlights that growth mindset might play an essential role in cultivating a student's grit level.

Maternal avoidance, anxiety cognitions and interactive behaviour predicts infant development at 12 months in the context of anxiety disorders in the postpartum period

BACKGROUND

Few studies have examined the relation between anxiety disorders in the postpartum period and cognitive as well as language development in infancy.

AIMS

This longitudinal study investigated whether anxiety disorder in the postpartum period is linked to infant development at twelve months. A closer look was also taken at a possible link between maternal interaction and infant development.

STUDY DESIGN

Subjects were videotaped during a Face-to-Face-Still-Face interaction with their infant (M = 4.0 months). Specific maternal anxiety symptoms were measured by self-report questionnaires (Anxiety Cognition Questionnaire (ACQ), Body Sensations Questionnaire (BSQ), Mobility Inventory (MI)) to check for a connection with infant development. The Bayley Scales of Infant and Toddler Development-III (Bayley-III) were used to assess infant language and cognitive development at one year of age.

SUBJECTS

n = 34 mothers with anxiety disorder (SCID-I; DSM-IV) and n = 47 healthy mothers with their infant.

OUTCOME MEASURES

Infant performance on Bayley-III language and cognitive scales.

RESULTS

Infants of mothers with anxiety disorder yielded significantly lower language scores than infants of controls. No significant group differences were found regarding infant cognitive development. Exploratory analyses revealed the vital role of "maternal avoidance accompanied" in infant language and cognitive development. Maternal neutral engagement, which lacks positive affect and vocalisations, turned out as the strongest negative predictor of cognitive development. Maternal anxiety cognitions and joint activity in mother-infant interaction were the strongest predictors of infant language performance.

CONCLUSIONS

Results underline the importance to also consider the interaction behaviour of women with anxiety disorders to prevent adverse infant development.

Diffusion tensor imaging of the structural integrity of white matter correlates with impulsivity in adolescents with internet gaming disorder

INTRODUCTION

Internet gaming disorder (IGD) is usually defined as the inability of an individual to control internet gaming resulting in serious negative consequences, and trait impulsivity has been viewed as a hallmark feature of IGD. Recent studies have suggested that the structural integrity of the white matter (WM) plays an important role in the neuromediation of an individual's impulsivity. However, no study has examined the association between WM integrity and impulsivity in IGD adolescents.

METHODS

In this study, 33 adolescents with IGD and 32 healthy controls (HCs) were recruited, and the intergroup differences in the relationships between impulsivity and fractional anisotropy (FA) values across the whole brain WM were investigated using voxel-wise correlation analyses.

RESULTS

Our results revealed significant intergroup differences in the correlations between impulsivity and the FA values of the right corticospinal tract (CST) and the right occipital WM. Region of interest-based tests revealed that the FA values of these clusters were positive or insignificantly correlated with impulsivity in the IGD adolescents contrasted to the significantly negative correlation in the HCs.

CONCLUSIONS

This altered correlations in the IGD adolescents might reflect potential WM microstructural changes which may be associated with the greater impulsivity of IGD adolescents and provide possible therapeutic targets for interventions in this population.

The overlapping brain region accounting for the relationship between procrastination and impulsivity: A voxel-based morphometry study

Procrastination is a prevalent problematic behavior that brings serious consequences, such as lower levels of health, wealth, and well-being. Previous research has verified that impulsivity is one of the traits most strongly correlated with procrastination. However, little is known about why there is a tight behavioral relationship between them. To address this question, we used voxel-based morphometry (VBM) to explore the common neural substrates between procrastination and impulsivity. In line with previous findings, the behavioral results showed a strong behavioral correlation between procrastination and impulsivity. Neuroimaging results showed impulsivity and procrastination shared the common neurobiological underpinnings in the dorsolateral prefrontal cortex (DLPFC) based on the data from 85 participants (sample 1). Furthermore, the mediation analysis revealed that impulsivity mediated the impact of gray matter (GM) volumes of this overlapping region in the DLPFC on procrastination on another independent 84 participants' data (sample 2). In conclusion, the overlapping brain region in the DLPFC would be responsible for the close relationship between procrastination and impulsivity. As a whole, the present study extends our knowledge on procrastination, and provides a novel perspective to explain the tight impulsivity - procrastination relationship.

The Right Superior Frontal Gyrus and Individual Variation in Proactive Control of Impulsive Response

A hallmark of cognitive control is the ability to rein in impulsive responses. Previously, we used a Bayesian model to describe trial-by-trial likelihood of the stop signal or p(Stop) and related regional activations to p(Stop) to response slowing in a stop signal task. Here, we characterized the regional processes of conflict anticipation in association with intersubject variation in impulse control in 114 young adults. We computed the stop signal reaction time (SSRT) and a measure of motor urgency, indexed by the reaction time (RT) difference between go and stop error trials or "GoRT - SERT," where GoRT is the go trial RT and SERT is the stop error RT. Motor urgency and SSRT were positively correlated across subjects. A linear regression identified regional activations to p(Stop), each in correlation with SSRT and motor urgency. We hypothesized that shared neural activities mediate the correlation between motor urgency and SSRT in proactive control of impulsivity. Activation of the ventromedial prefrontal cortex, posterior cingulate cortex and right superior frontal gyrus (SFG) during conflict anticipation correlated negatively with the SSRT. Activation of the right SFG also correlated negatively with GoRT - SERT. Therefore, activation of the right SFG was associated with more efficient response inhibition and less motor urgency. A mediation analysis showed that right SFG activation to conflict anticipation mediates the correlation between SSRT and motor urgency bidirectionally. The current results highlight a specific role of the right SFG in translating conflict anticipation to the control of impulsive response, which is consistent with earlier studies suggesting its function in action restraint.

SIGNIFICANCE STATEMENT

Individuals vary in impulse control. However, the neural bases underlying individual variation in proactive control of impulsive responses remain unknown. Here, in a large sample of young adults, we showed that activation of the right superior frontal gyrus (SFG) during conflict anticipation is positively correlated with the capacity of inhibitory control and negatively with motor urgency in the stop signal task. Importantly, activity of the right SFG mediates the counteracting processes of inhibitory control and motor urgency across subjects. The results support a unique role of the right SFG in individual variation in cognitive control.