Adolescents rats engage the orbitofrontal-striatal pathway differently than adults during impulsive actions.

Adolescence is characterized by increased impulsive and risk-taking behaviors. To better understand the neural networks that subserves impulsivity in adolescents, we used a reward-guided behavioral model that quantifies age differences in impulsive actions in adult and adolescent rats of both sexes. Using chemogenetics, we identified orbitofrontal cortex (OFC) projections to the dorsomedial striatum (DMS) as a critical pathway for age-related execution of impulsive actions. Simultaneous recording of single units and local field potentials in the OFC and DMS during task performance revealed an overall muted response in adolescents during impulsive actions as well as age-specific differences in theta power and OFC-DMS functional connectivity. Collectively, these data reveal that the OFC-DMS pathway is critical for age-differences in reward-guided impulsive actions and provide a network mechanism to enhance our understanding of how adolescent and adult brains coordinate behavioral inhibition.

An updated review on animal models to study attention-deficit hyperactivity disorder.

Attention-deficit hyperactivity disorder (ADHD) is a neuropsychiatric disorder affecting both children and adolescents. Individuals with ADHD experience heterogeneous problems, such as difficulty in attention, behavioral hyperactivity, and impulsivity. Recent studies have shown that complex genetic factors play a role in attention-deficit hyperactivity disorders. Animal models with clear hereditary traits are crucial for studying the molecular, biological, and brain circuit mechanisms underlying ADHD. Owing to their well-managed genetic origins and the relative simplicity with which the function of neuronal circuits is clearly established, models of mice can help learn the mechanisms involved in ADHD. Therefore, in this review, we highlighting the important genetic animal models that can be used to study ADHD.

Psychometric properties of the Chinese version of the Quick Delay Questionnaire (C-QDQ) and ecological characteristics of reward-delay impulsivity of adults with ADHD.

BACKGROUND: The Quick Delay Questionnaire (QDQ) is a short questionnaire designed to assess delay-related difficulties in adults. This study aimed to examine the reliability and validity of the Chinese version of the QDQ (C-QDQ) in Chinese adults, and explore the ecological characteristics of delay-related impulsivity in Chinese adults with attention-deficit/hyperactivity disorder (ADHD). METHODS: Data was collected from 302 adults, including ADHD (n = 209) and healthy controls (HCs) (n = 93). All participants completed the C-QDQ. The convergent validity, internal consistency, retest reliability and confirmatory factor analysis (CFA) of the C-QDQ were analyzed. The correlations between C-QDQ and two laboratory measures of delay-related difficulties and Barratt Impulsiveness Scale-11 (BIS-11), the comparison of C-QDQ scores between ADHD subgroups and HCs were also analyzed. RESULTS: The Cronbach's α of C-QDQ was between 0.83 and 0.89. The intraclass correlation coefficient of C-QDQ was between 0.80 and 0.83. The results of CFA of C-QDQ favoured the original two-factor model (delay aversion and delay discounting). Significant positive associations were found between C-QDQ scores and BIS-11 total score and performance on the laboratory measure of delay-related difficulties. Participants with ADHD had higher C-QDQ scores than HCs, and female ADHD reported higher scores on delay discounting subscale than male. ADHD-combined type (ADHD-C) reported higher scores on delay aversion subscale than ADHD-inattention type (ADHD-I). CONCLUSION: The C-QDQ is a valid and reliable tool to measure delay-related responses that appears to have clinical utility. It can present the delay-related impulsivity of patients with ADHD. Compared to HCs, the level of reward-delay impulsivity was higher in ADHD.

Differences in Discounting Behavior and Brain Responses for Food and Money Reward.

Most neuroeconomic research seeks to understand how value influences decision-making. The influence of reward type is less well understood. We used functional magnetic resonance imaging (fMRI) to investigate delay discounting of primary (i.e., food) and secondary rewards (i.e., money) in 28 healthy, normal-weighted participants (mean age = 26.77; 18 females). To decipher differences in discounting behavior between reward types, we compared how well-different option-based statistical models (exponential, hyperbolic discounting) and attribute-wise heuristic choice models (intertemporal choice heuristic, dual reasoning and implicit framework theory, trade-off model) captured the reward-specific discounting behavior. Contrary to our hypothesis of different strategies for different rewards, we observed comparable discounting behavior for money and food (i.e., exponential discounting). Higher k values for food discounting suggest that individuals decide more impulsive if confronted with food. The fMRI revealed that money discounting was associated with enhanced activity in the right dorsolateral prefrontal cortex, involved in executive control; the right dorsal striatum, associated with reward processing; and the left hippocampus, involved in memory encoding/retrieval. Food discounting, instead, was associated with higher activity in the left temporoparietal junction suggesting social reinforcement of food decisions. Although our findings do not confirm our hypothesis of different discounting strategies for different reward types, they are in line with the notion that reward types have a significant influence on impulsivity with primary rewards leading to more impulsive choices.

Effects of yoga on impulsivity in patients with and without mental disorders: a systematic review.

BACKGROUND: Yoga can be used as a complementary intervention to conventional treatments, whether pharmacological or non-pharmacological. Sustained practice of yoga can generate a series of benefits for individuals' quality of life and improve their physical fitness. OBJECTIVE: To investigate the potential effects of yoga as an adjunct intervention in conditions involving impulse control issues, such as attention deficit hyperactivity disorder (ADHD), borderline personality disorder, bipolar affective disorder, and substance use disorders. METHODS: We performed a systematic review of placebo-controlled, randomized trials of yoga in patients with impulsivity. PubMed, Web of Science, and Science Direct databases were searched for trials published up to January, 2023. Data were extracted from published reports and quality assessment was performed per Cochrane recommendations. RESULTS: Out of 277 database results, 6 RCT were included in this systematic review. To assess the level of attention and impulsiveness, the following scales were analyzed: Barratt Impulsiveness, UPPS-P Impulsive Behavior scale, Conners' Continuous Performance Test IIª and Conners' Parent Rating Scale-Revised: Long. CONCLUSIONS: Yoga didn't have a significant improvement in impulsivity when compared to placebo. There are many tools to assess impulsivity, but they mean different concepts and domains consisting in a weakness on comparison of yoga effects. PROSPERO REGISTRATION: CRD42023389088.

El papel de la impulsividad en la orientación al suicidio de universitarios con antecedentes de conducta autolesiva / The role of impulsivity in suicidal orientation of university students with a history of self-injurious behavior

El objetivo de esta investigación fue describir el efecto de la depresión, la desesperanza y la impulsividad sobre la orientación al suicidio y el papel de la impulsividad como mediador de la orientación suicida en universitarios con antecedentes de conductas autolesivas. Participaron 1.645 jóvenes entre los 18 y 29 años, de dos ciudades colombianas. Se seleccionaron 218 jóvenes (M= 21,00; DT= 2,99) que informaron de al menos un intento de suicidio en el último año, quienes contestaron el “Inventario de orientación suicida”, la “Escala de desesperanza de Beck”, el “Inventario de depresión de Beck” y la “Escala de impulsividad de Barratt”. La depresión, la desesperanza y la impulsividad explicaron el 63% de la variación de la orientación al suicidio (R2= 0,635; IC 95% [0,555; 0,713]; p= 0,001). La impulsividad medió con depresión en aquellos casos en los que la orientación suicida era alta, cuyos efectos totales, directos e indirectos, fueron estadísticamente significativos (p< 0,001). La impulsividad desempeña un papel mediador entre la depresión y la desesperanza en la predicción de la orientación suicida.(AU)

The aim of this research was to describe the effect of depression,hopelessness, and impulsivity on orientation to suicide and the role of impulsivityas a mediator of suicidal orientation in university students with a history of self-injury behaviors. 1645 young people between 18 and 29 years old participated,from two Colombian cities. 218 young people were selected (M= 21.00; SD= 2.99)who reported at least one suicide attempt in the last year, who answered the“Suicidal Orientation Inventory”, the “Beck Hopelessness Scale”, the “BeckDepression Inventory” and the “Barratt Impulsivity Scale”. Depression,hopelessness, and impulsivity explained 63% of the variation in suicidal orientation (R 2 = .635, IC 95% [.555, .713], p= .001). Impulsivity mediated with depression inthose cases in which suicidal orientation was high, whose total, direct and indirecteffects were statistically significant (p< .001). Impulsivity plays a mediating rolebetween depression and hopelessness in predicting suicidal orientation.K EY WORDS : depression, hopelessness, impulsivity, suicidality, college youth.(AU)

The mediating effect of attentional impulsivity between mindfulness and problematic smartphone use.

OBJECTIVE: Problematic smartphone use has been linked to lower levels of mindfulness, impaired attentional function, and higher impulsivity. This study aimed to identify the psychological mechanisms of problematic smartphone use by exploring the relationship between addictive smartphone use, mindfulness, attentional function and impulsivity. METHODS: Ninety participants were evaluated with the smartphone addiction proneness scale and classified into the problematic smartphone use group (n = 42; 24 women; mean age: 27.6 ± 7.2 years) or normal use group (n = 48; 22 women; mean age: 30.1 ± 5.7 years). All participants completed self-report questionnaires evaluating their trait impulsivity and mindfulness and attention tests that assessed selective, sustained and divided attention. We compared the variables between the groups and explored the relationship between mindfulness, attentional function, impulsivity and addictive smartphone use through mediation analysis. RESULTS: The problematic smartphone use group showed higher trait impulsivity and lower mindfulness than the normal use group. There were no significant group differences in performance on attention tests. Levels of addictive smartphone use were significantly correlated with higher levels of trait impulsivity and lower levels of mindfulness, but not with performance on attention tests. Mediation analysis showed that acting with awareness, an aspect of mindfulness, reduces the degree of addictive smartphone use through attentional impulsivity, one of the trait impulsivity. CONCLUSION: Acting without sufficient awareness could influence addictive smartphone use by mediating attentional impulsivity. This supports that executive control deficits, reflected in high attentional impulsivity, contribute to problematic smartphone use. Our findings imply that mindfulness-based interventions can enhance executive control over smartphone use by promoting awareness.

Impulsivity mediates the association between narcissism and substance-related problems beyond the degree of substance use: a longitudinal observational study.

BACKGROUND: Narcissism has been implied as a putative risk factor for substance use disorders (SUDs). However, previous research did not disentangle the degree of substance use from substance-related problems, the symptoms of SUDs. This preregistered study addressed the open question whether grandiose and vulnerable narcissism and their constituent traits convey specific SUD risk, that is, explain substance-related problems beyond the degree of use. Furthermore, we tested whether impulsivity or substance use motives linked to narcissistic self-regulation mediate this association. METHODS: Narcissism, impulsivity, substance use motives, past-year substance use, and substance-related problems were assessed in 139 (poly-)substance users, 121 of whom completed a one-year follow-up. For significant longitudinal associations between narcissism factors and substance-related problems controlled for the degree of use, we tested impulsivity and substance use motives as mediators. RESULTS: Grandiose narcissism (r =.24, p =.007) and its constituent factors antagonistic (r =.27, p =.003) and agentic narcissism (r =.18, p =.050), but not vulnerable narcissism, prospectively predicted substance-related problems beyond the degree of substance use. Associations of grandiose narcissism and antagonistic narcissism with substance-related problems were fully mediated by impulsivity, but not substance use motives. Impulsivity explained roughly one third of the association of both grandiose (P̂M = 0.30) and antagonistic narcissism (P̂M = 0.26) with substance-related problems. DISCUSSION: We demonstrate that grandiose narcissism- particularly antagonistic but also agentic narcissism- is specifically linked to substance-related problems beyond the degree of substance use. The mediating effect of impulsivity but not substance use motives suggests that impulsivity may be a more important mechanism than narcissistic self-regulation in promoting SUD in narcissism. However, future studies may use more targeted measures than substance use motives to further probe the role of self-regulation. Similar result patterns for alcohol compared to all substances together indicate that mechanisms may be alike across substances. In conclusion, narcissistic individuals may not use substances more but have a higher SUD risk, informing prevention and treatment.

Gamification and motivation: Impact on delay discounting performance.

Delay discounting is a phenomenon strongly associated with impulsivity. However, in order for a measured discounting rate in an experiment to meaningfully generalize to choices made elsewhere in life, participants must provide thoughtful, engaged answers during the assessment. Classic discounting tasks may not optimize intrinsic motivation or enjoyment, and a participant who is disengaged from the task is likely to behave in a way that provides a biased estimate of their discounting function. We assessed degree of delay discounting in a task intended to vary level of participant motivation. This was accomplished by introducing varying levels of gamification, the application of game design principles to a non-game context. Experiment 1 compared three versions of the delay discounting task with differing degrees of gamification and compared performance and task enjoyment across those variations, while Experiment 2 used two conditions (one gamified, one not). Participants found more gamified versions of the task more enjoyable than the other conditions, without producing substantial between-group differences in most cases. Thus, more polished task gameplay can provide a more enjoyable experience for participants without undermining delay discounting effects commonly reported in the literature. We also found that in all experimental conditions, higher levels of interest in or enjoyment of the task tended to be associated with more rapid discounting. This may suggest that low task motivation may result in less impulsive choice and suggests that participants who find delay discounting experiments sufficiently boring may bias assessments of value across delays.

Why consumers have impulsive purchase behavior in live streaming: the role of the streamer.

To explore the influencing factors of consumers' impulsive purchase behavior in live streaming, based on the Stimulus-Organism-Response framework, we construct the model of how streamers influence consumers' impulsive purchase behavior by consulting literature. Collected data by means of a questionnaire, and made an empirical study by using the structural equation model to explore the mechanism of streamer affecting consumers' impulsive purchase behavior. The results show that streamer characteristics (personal charisma, professionalism) and streamer performance (interactivity, entertainment) affect consumers' impulsive purchase behavior by affecting consumers' trust and flow experience. The empirical results have important theoretical and practical significance.

Disentangling the neurobiological bases of temporal impulsivity in Huntington's disease.

BACKGROUND: Despite its impact on daily life, impulsivity in Huntington's disease (HD) is understudied as a neuropsychiatric symptom. Our aim is to characterize temporal impulsivity in HD and to disentangle the white matter correlate associated with impulsivity. METHODS: Forty-seven HD individuals and 36 healthy controls were scanned and evaluated for temporal impulsivity using a delay-discounting (DD) task and complementary Sensitivity to Punishment and Sensitivity to Reward Questionnaire. Diffusion tensor imaging was employed to characterize the structural connectivity of three limbic tracts: the uncinate fasciculus (UF), the accumbofrontal tract (NAcc-OFC), and the dorsolateral prefrontal cortex connectig the caudate nucleus (DLPFC-cn). Multiple linear regression analyses were applied to analyze the relationship between impulsive behavior and white matter microstructural integrity. RESULTS: Our results revealed altered structural connectivity in the DLPC-cn, the NAcc-OFC and the UF in HD individuals. At the same time, the variability in structural connectivity of these tracts was associated with the individual differences in temporal impulsivity. Specifically, increased structural connectivity in the right NAcc-OFC and reduced connectivity in the left UF were associated with higher temporal impulsivity scores. CONCLUSIONS: The present findings highlight the importance of investigating the spectrum of temporal impulsivity in HD. As, while less prevalent than other psychiatric features, this symptom is still reported to significantly impact the quality of life of patients and caregivers. This study provides evidence that individual differences observed in temporal impulsivity may be explained by variability in limbic frontostriatal tracts, while shedding light on the role of sensitivity to reward in modulating impulsive behavior through the selection of immediate rewards.

Users' unverified information-sharing behavior on social media: The role of reasoned and social reactive pathways.

Unverified or false information spread by irresponsible users can amplify the dissemination of fake news or misinformation. This phenomenon may not only undermine the credibility of social media platforms but also pose severe consequences for individuals and society. This study applies and extends the prototypical willingness model with the aim of comprehending the reasons, and decision-making process driving users' unverified information-sharing behavior a reasoned and intended pathway or an impulsive and unconscious one. Data from a sample of 646 users were analyzed using Structural Equation Modeling to assess the determinative effect of both the reasoned pathway (attitude toward unverified information-sharing, subjective norm, and perceived behavioral control) and the social-reaction pathway (prototype favorability and similarity). Findings highlight the substantial role of the social-reaction pathway in forecasting users' unverified information-sharing behavior, with prototype similarity and attitude being the dominant predictors. Meanwhile, components of the reasoned pathway, specifically perceived behavior control, and attitude, also exhibited significant contributions toward predicting the behavior. In summary, while a deliberate, reasoned process has some influence, the sharing of unverified information on social media by users is primarily an intuitive, spontaneous response to specific online circumstances. This study therefore offers valuable insights that could aid relevant stakeholders in effectively regulating the spread of misinformation. Against this backdrop, highlighting potential risks associated with sharing unverified information and the negative portrayal of users propagating misinformation may contribute to the development of a more critical perspective toward online information sharing by users themselves.

Differentiating action from inaction: Longitudinal relations among impulsive personality traits, internalizing symptoms, and drinking behavior.

BACKGROUND: Impulsive personality traits are strong, consistent risk factors for heavy drinking, and modern theories suggest that impulsive traits may also confer risk for internalizing symptoms. However, it remains unclear which specific impulsive traits are linked with heavy drinking versus internalizing symptoms, and whether heavy drinking and internalizing symptoms are mechanisms of risk for negative alcohol consequences in impulsive individuals. METHOD: Data are from a longitudinal study of young adults (N = 448, Mage = 22.27, 43.5 % female) assessed at baseline (T1), 6 months (T2), and one year later (T3). Longitudinal path models tested whether T1 impulsive traits (i.e., lack of premeditation, lack of perseverance, sensation seeking, positive urgency, negative urgency) were indirectly associated with T3 negative alcohol consequences through heavy T2 drinking and T2 internalizing symptoms (i.e., depression, anxiety, stress). Separate models were tested for positive and negative urgency given strong correlations between these measures. RESULTS: Across models, T1 lack of premeditation indirectly predicted more T3 negative alcohol consequences through heavy T2 drinking. When tested separately, T1 negative urgency indirectly predicted more T3 negative consequences through higher T2 stress and depressive (but not anxiety) symptoms, and T1 positive urgency predicted higher T2 anxiety symptoms, but T2 anxiety was unrelated to T3 negative consequences. Across models, T1 sensation seeking indirectly predicted less T3 negative consequences through decreased T2 depression. CONCLUSIONS: Distinct impulsive traits prospectively predicted heavy drinking and internalizing symptoms, both of which conferred risk for negative alcohol consequences. Findings underscore the importance of targeted interventions based on personality and suggest that decreases in drinking may be more effective prevention for those who lack premeditation, whereas decreases in internalizing, particularly depression/stress, may be critical for those high in negative urgency.

Topological features of functional brain networks and subclinical impulsivity: an investigation in younger and older adults.

Impulsive traits (i.e., the tendency to act without forethought regardless of negative outcomes) are frequently found in healthy populations. When exposed to risk factors, individuals may develop debilitating disorders of impulse control (addiction, substance abuse, gambling) characterized by behavioral and cognitive deficits, eventually leading to huge socioeconomic costs. With the far-reaching aim of preventing the onset of impulsive disorders, it is relevant to investigate the topological organization of functional brain networks associated with impulsivity in sub-clinical populations. Taking advantage of the open-source LEMON dataset, we investigated the topological features of resting-state functional brain networks associated with impulsivity in younger (n = 146, age: 20-35) and older (n = 61, age: 59-77) individuals, using a graph-theoretical approach. Specifically, we computed indices of segregation and integration at the level of specific circuits and nodes known to be involved in impulsivity (frontal, limbic, and striatal networks). In younger individuals, results revealed that impulsivity was associated with a more widespread, less clustered and less efficient functional organization, at all levels of analyses and in all selected networks. Conversely, impulsivity in older individuals was associated with reduced integration and increased segregation of striatal regions. Speculatively, such alterations of functional brain networks might underlie behavioral and cognitive abnormalities associated with impulsivity, a working hypothesis worth being tested in future research. Lastly, differences between younger and older individuals might reflect the implementation of age-specific adaptive strategies, possibly accounting for observed differences in behavioral manifestations. Potential interpretations, limitations and implications are discussed.

Genome-wide association studies (GWAS) and post-GWAS analyses of impulsivity: A systematic review.

Impulsivity is related to a host of mental and behavioral problems. It is a complex construct with many different manifestations, most of which are heritable. The genetic compositions of these impulsivity manifestations, however, remain unclear. A number of genome-wide association studies (GWAS) and post-GWAS analyses have tried to address this issue. We conducted a systematic review of all GWAS and post-GWAS analyses of impulsivity published up to December 2023. Available data suggest that single nucleotide polymorphisms (SNPs) in more than a dozen of genes (e.g., CADM2, CTNNA2, GPM6B) are associated with different measures of impulsivity at genome-wide significant levels. Post-GWAS analyses further show that different measures of impulsivity are subject to different degrees of genetic influence, share few genetic variants, and have divergent genetic overlap with basic personality traits such as extroversion and neuroticism, cognitive ability, psychiatric disorders, substance use, and obesity. These findings shed light on controversies in the conceptualization and measurement of impulsivity, while providing new insights on the underlying mechanisms that yoke impulsivity to psychopathology.

The maltreated eco-phenotype of eating disorders: A new diagnostic specifier? A systematic review of the evidence and comprehensive description.

This systematic review aimed to summarize the evidence on the existence of a distinct phenotypic expression of Eating Disorders (EDs) associated with childhood maltreatment (CM), the so-called maltreated eco-phenotype of EDs. PRISMA standards were followed. Articles providing data about the characteristics of individuals with an ED reporting CM were included. Relevant results were extracted and summarized. A quality assessment was performed. A total of 1207 records were identified and screened, and 97 articles published between 1994 and 2023 were included. Findings revealed distinct biological and clinical features in patients with EDs reporting CM, including neuroanatomical changes, altered stress responses, ghrelin levels, inflammation markers, and gut microbiota composition. Clinically, CM correlated with severer eating behaviors, higher psychiatric comorbidity, impulsivity, emotional dysregulation, and risky behaviors. Additionally, CM was associated with poorer treatment outcomes, especially in general psychopathology and psychiatric comorbidities. This review highlighted the need to move towards an etiologically informed nosography, recognizing CM not merely as a risk factor, but also as an etiologic agent shaping different eco-phenotypic variants of EDs.

Association between endocrine and neuropsychological endophenotypes and gambling disorder severity.

BACKGROUND: Neurobiological characteristics have been identified regarding the severity of gambling disorder (GD). The aims of this study were: (1) to examine, through a path analysis, whether there was a relationship between neuroendocrine features, potentially mediational GD variables, and GD severity, and (2) to associate neuroendocrine variables, with GD severity-related variables according to gambling preferences. METHODS: The sample included 297 outpatients with GD. We analyzed endocrine concentrations of different appetite-related hormones (ghrelin, liver antimicrobial peptide 2 [LEAP-2], leptin, adiponectin), and neuropsychological performance (working memory, cognitive flexibility, inhibition, decision making, premorbid intelligence). Path analysis assessed mechanisms between neuroendocrine features and GD severity, including mediational GD variables (impulsivity traits and gambling-related cognitive distortions). Partial correlations evaluated the associations between neuroendocrine variables, including impulsivity traits, and variables related to GD severity (DSM-5, South Oaks Gambling Screen, illness duration, and gambling-related cognitive distortions). RESULTS: Lower adiponectin concentrations predicted greater GD severity, while higher LEAP-2 concentrations predicted more gambling-related cognitive distortions. Likewise, better neuropsychological performance directly predicted GD severity, but worse neuropsychological performance was associated with GD severity through the mediational variables of impulsivity traits and gambling-related cognitive distortions. Also, in non-strategic individuals with GD, poor working memory was associated with gambling expectancies and predictive control. In strategic individuals with GD, poor cognitive flexibility was associated with illusion of control, predictive control, and inability to stop gambling. CONCLUSIONS: These results provide updated information about the comprehension of the interaction between neuroendocrine features, clinical variables, and severity of GD. Thus, neurobiological functions seem to be strongly related to GD severity.

Suboptimal decision making and interpersonal problems in ADHD: longitudinal evidence from a laboratory task.

Over half of children with Attention-Deficit/Hyperactivity Disorder (ADHD) display interpersonal and social problems. Several lines of research suggest that suboptimal decision making, the ability to adjust choices to different risk-varying options, influences poorer choices made in social interactions. We thus measured decision making and its prediction of social problems longitudinally with the Cambridge Gambling Task in children with ADHD over four years. Children with ADHD had shown suboptimal decision making driven mainly by delay aversion at baseline and we expected this to be a stabile trait which would predict greater parent-reported social problems. From the baseline assessment (n = 70), 67% participated at the follow-up assessment, 21 from the ADHD group and 26 from the typically developing group. The mean age at the follow-up was 14.5 years old. The results confirmed our expectations that suboptimal decision making was a stabile trait in children and adolescents with ADHD. Although delay aversion did not differ from controls at follow-up it still proved to be the main longitudinal predictor for greater social problems. Our findings indicate that impulsivity in social interactions may be due to a motivational deficit in youth with ADHD.

Choice impulsivity after repeated social stress is associated with increased perineuronal nets in the medial prefrontal cortex.

Repeated stress can predispose to substance abuse. However, behavioral and neurobiological adaptations that link stress to substance abuse remain unclear. This study investigates whether intermittent social defeat (ISD), a stress protocol that promotes drug-seeking behavior, alters intertemporal decision-making and cortical inhibitory function in the medial prefrontal cortex (mPFC). Male long evans rats were trained in a delay discounting task (DDT) where rats make a choice between a fast (1 s) small reward (1 sugar pellet) and a large reward (3 sugar pellets) that comes with a time delay (10 s or 20 s). A decreased preference for delayed rewards was used as an index of choice impulsivity. Rats were exposed to ISD and tested in the DDT 24 h after each stress episode, and one- and two-weeks after the last stress episode. Immunohistochemistry was performed in rat's brains to evaluate perineuronal nets (PNNs) and parvalbumin GABA interneurons (PV) labeling as markers of inhibitory function in mPFC. ISD significantly decreased the preference for delayed large rewards in low impulsive, but not high impulsive, animals. ISD also increased the density of PNNs in the mPFC. These results suggest that increased choice impulsivity and cortical inhibition predispose animals to seek out rewards after stress.

Gray matter volume associations in youth with ADHD features of inattention and hyperactivity/impulsivity.

BACKGROUND: Prior research has shown smaller cortical and subcortical gray matter volumes among individuals with attention-deficit/hyperactivity disorder (ADHD). However, neuroimaging studies often do not differentiate between inattention and hyperactivity/impulsivity, which are distinct core features of ADHD. The present study uses an approach to disentangle overlapping variance to examine the neurostructural heterogeneity of inattention and hyperactivity/impulsivity dimensions. METHODS: We analyzed data from 10,692 9- to 10-year-old children from the Adolescent Brain Cognitive Development (ABCD) Study. Confirmatory factor analysis was used to derive factors representing inattentive and hyperactive/impulsive traits. We employed structural equation modeling to examine these factors' associations with gray matter volume while controlling for the shared variance between factors. RESULTS: Greater endorsement of inattentive traits was associated with smaller bilateral caudal anterior cingulate and left parahippocampal volumes. Greater endorsement of hyperactivity/impulsivity traits was associated with smaller bilateral caudate and left parahippocampal volumes. The results were similar when accounting for socioeconomic status, medication, and in-scanner motion. The magnitude of these findings increased when accounting for overall volume and intracranial volume, supporting a focal effect in our results. CONCLUSIONS: Inattentive and hyperactivity/impulsivity traits show common volume deficits in regions associated with visuospatial processing and memory while at the same time showing dissociable differences, with inattention showing differences in areas associated with attention and emotion regulation and hyperactivity/impulsivity associated with volume differences in motor activity regions. Uncovering such biological underpinnings within the broader disorder of ADHD allows us to refine our understanding of ADHD presentations.