Impulsive behavior in adults with attention deficit/ hyperactivity disorder: characterization of attentional, motor and cognitive impulsiveness

The Relationship Between Social Anxiety Disorder and ADHD in Adolescents and Adults: A Systematic Review

OBJECTIVE

This review aimed to systematically gather empirical data on the link between social anxiety disorder and ADHD in both clinical and non-clinical populations among adolescents and adults.

METHOD

Literature searches were conducted in PsycInfo, PubMed, Scopus, and Web of Science, resulting in 1,739 articles. After screening, 41 articles were included. Results were summarized using a narrative approach.

RESULTS

The prevalence of ADHD in adolescents and adults with SAD ranged from 1.1% to 72.3%, while the prevalence of SAD in those with ADHD ranged from 0.04% to 49.5%. Studies indicate that individuals with both SAD and ADHD exhibit greater impairments. All studies were judged to be of weak quality, except for two studies which were rated moderate quality.

DISCUSSION

Individuals with SAD should be screened for ADHD and vice versa, to identify this common comorbidity earlier. Further research is needed to better understand the prevalence of comorbid ADHD and SAD in adolescents.

A systematic review of the utility of continuous performance tests among adults with ADHD

OBJECTIVE

The clinical utility of continuous performance tests (CPTs) among adults with attention-deficit/hyperactivity disorder (ADHD) has increasingly been brought under question. Therefore, the objective of this study was to systematically review the literature to investigate the clinical utility of various commercially available CPTs, including the Conner's Continuous Performance Test (CCPT), Test of Variables of Attention (TOVA), Gordon Diagnostic System (GDS), and Integrated Visual and Auditory Continuous Performance Test (IVA) in the adult ADHD population.

METHODS

This systematic review followed the a priori PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Articles were gathered from PsycINFO, PsycARTICLES, Academic Search Complete, and Google Scholar on 11 April 2022. Sixty-nine articles were included in the final review. Risk of bias was assessed using the National Institute of Health Quality Assessment Took for Observational Cohort and Cross-Sectional Studies.

RESULTS

Most articles demonstrated high risk of bias, and there was substantial heterogeneity across studies. Overall, the reviewed CPTs appeared to have limited diagnostic utility and classification accuracy. Although many studies showed differing scores between adults with ADHD and comparison groups, findings were not consistent. Characteristics of CPT performances among adults with ADHD were mixed, with little consistency and no evidence of a clear profile of performances; however, CCPT commission errors appeared to have the most utility when used a treatment or experimental outcome measure, compared to other CCPT scores.

CONCLUSION

Overall, CPTs should not be used in isolation as a diagnostic test but may be beneficial when used as a component of a comprehensive assessment.

Does Emotion-Related Impulsivity Relate to Specific ADHD Symptom Dimensions, and Do the Effects Generalize Across Comorbid Internalizing and Externalizing Syndromes?

BACKGROUND

Recent work highlights the role of emotion dysregulation in the pathology of Attention-Deficit/Hyperactivity Disorder (ADHD). As such, emotion-related impulsivity (ERI), the trait-like tendency toward disinhibited thoughts (Pervasive Influence of Feelings, PIF) and actions (Feelings Trigger Action, FTA) during heightened emotional states, may be particularly relevant. We explored whether Inattention (IN) and Hyperactivity/Impulsivity (HI), two core symptom dimensions of ADHD, would relate to distinct facets of ERI, and whether externalizing and internalizing symptoms would moderate these relations.

METHOD

Using structural equation modeling, we examined hypotheses among 364 adults recruited for high internalizing and externalizing symptoms.

RESULTS

We identified significant paths for FTA regressed on HI and PIF regressed on IN, supporting our hypotheses about main effects. Moderating paths were not significant.

CONCLUSIONS

IN and HI correlate with distinct forms of ERI, These effects appear to generalize across co-occurring internalizing and externalizing symptoms. Theoretical and clinical implications are discussed.

SLCO5A1 and synaptic assembly genes contribute to impulsivity in juvenile myoclonic epilepsy

Elevated impulsivity is a key component of attention-deficit hyperactivity disorder (ADHD), bipolar disorder and juvenile myoclonic epilepsy (JME). We performed a genome-wide association, colocalization, polygenic risk score, and pathway analysis of impulsivity in JME (n = 381). Results were followed up with functional characterisation using a drosophila model. We identified genome-wide associated SNPs at 8q13.3 (P = 7.5 × 10-9) and 10p11.21 (P = 3.6 × 10-8). The 8q13.3 locus colocalizes with SLCO5A1 expression quantitative trait loci in cerebral cortex (P = 9.5 × 10-3). SLCO5A1 codes for an organic anion transporter and upregulates synapse assembly/organisation genes. Pathway analysis demonstrates 12.7-fold enrichment for presynaptic membrane assembly genes (P = 0.0005) and 14.3-fold enrichment for presynaptic organisation genes (P = 0.0005) including NLGN1 and PTPRD. RNAi knockdown of Oatp30B, the Drosophila polypeptide with the highest homology to SLCO5A1, causes over-reactive startling behaviour (P = 8.7 × 10-3) and increased seizure-like events (P = 6.8 × 10-7). Polygenic risk score for ADHD genetically correlates with impulsivity scores in JME (P = 1.60 × 10-3). SLCO5A1 loss-of-function represents an impulsivity and seizure mechanism. Synaptic assembly genes may inform the aetiology of impulsivity in health and disease.

Microtemporal Dynamics of Dietary Intake, Physical Activity, and Impulsivity in Adult Attention-Deficit/Hyperactivity Disorder: Ecological Momentary Assessment Study Within Nutritional Psychiatry

BACKGROUND

Increasing attention is being paid to lifestyle factors, such as nutrition and physical activity (PA), as potential complementary treatment options in attention-deficit/hyperactivity disorder (ADHD). Previous research indicates that sugar and saturated fat intake may be linked to increased impulsivity, a core symptom of ADHD, whereas protein intake and PA may be related to reduced impulsivity. However, most studies rely on cross-sectional data that lack microtemporal resolution and ecological validity, wherefore questions of microtemporal dynamics (eg, is the consumption of foods high in sugar associated with increased impulsivity within minutes or hours?) remain largely unanswered. Ecological momentary assessment (EMA) has the potential to bridge this gap.

OBJECTIVE

This study is the first to apply EMA to assess microtemporal associations among macronutrient intake, PA, and state impulsivity in the daily life of adults with and without ADHD.

METHODS

Over a 3-day period, participants reported state impulsivity 8 times per day (signal-contingent), recorded food and drink intake (event-contingent), and wore an accelerometer. Multilevel 2-part models were used to study the association among macronutrient intake, PA, and the probability to be impulsive as well as the intensity of impulsivity (ADHD: n=36; control: n=137).

RESULTS

No association between macronutrient intake and state impulsivity was found. PA was not related to the intensity of impulsivity but to a higher probability to be impulsive (ADHD: β=-.09, 95% CI -0.14 to -0.04; control: β=-.03, 95% CI -0.05 to -0.01). No evidence was found that the combined intake of saturated fat and sugar amplified the increase in state impulsivity and that PA alleviated the positive association between sugar or fat intake and state impulsivity.

CONCLUSIONS

Important methodological considerations are discussed that can contribute to the optimization of future EMA protocols. EMA research in the emerging field of nutritional psychiatry is still in its infancy; however, EMA is a highly promising and innovative approach as it offers insights into the microtemporal dynamics of psychiatric symptomology, dietary intake, and PA in daily life.

Suicidal thoughts and behaviours among military veterans: protocol for a prospective, observational, neuroimaging study

INTRODUCTION

This study's overarching goal is to examine the relationship between brain circuits and suicidal thoughts and behaviours (STBs) in a transdiagnostic sample of US military veterans. Because STBs have been linked with maladaptive decision-making and disorders linked to impulsivity, this investigation focuses on valence and inhibitory control circuits.

METHODS AND ANALYSIS

In this prospective, observational study, we will collect functional MRI (fMRI), cognitive and clinical data from 136 veterans (target sample size) recruited from the Providence VA Health System (PVAHS): 68 with STBs and 68 matched controls. Behavioural data will be collected using standardised measures of STBs, psychiatric symptoms, cognition, functioning and medical history. Neuroimaging data will include structural, task and resting fMRI. We will conduct follow-up interviews and assessments at 6, 12 and 24 months post-enrolment. Primary analyses will compare data from veterans with and without STBs and will also evaluate whether activation and connectivity within circuits of valence and inhibition covary with historical and prospective patterns of suicidal ideation and behaviour.

ETHICS AND DISSEMINATION

The PVAHS Institutional Review Board approved this study (2018-051). Written informed consent will be obtained from all participants. Findings from this study will be published in peer-reviewed journals and presented at local, regional, national and international conferences.Nauder Namaky, Ph.D.* nauder_namaky@brown.edu.

Decision-making and frontoparietal resting-state functional connectivity among impulsive-compulsive diagnoses. Insights from a Bayesian approach

The Iowa Gambling Task (IGT) is one of the most widely used paradigms for assessing decision-making. An impairment in this process may be linked to several psychopathological disorders, such as obsessive-compulsive disorder (OCD), substance abuse disorder (SUD) or attention-deficit/hyperactivity disorder (ADHD), which could make it a good candidate for being consider a transdiagnostic domain. Resting-state functional connectivity (rsFC) has been proposed as a promising biomarker of decision-making. In this study, we aimed to identify idiosyncratic decision-making profiles among healthy people and impulsive-compulsive spectrum patients during the IGT, and to investigate the role of frontoparietal network (FPN) rsFC as a possible biomarker of different decision-making patterns. Using functional near-infrared spectroscopy (fNIRS), rsFC of 114 adults (34 controls; 25 OCD; 41 SUD; 14 ADHD) was obtained. Then, they completed the IGT. Hybrid clustering methods based on individual deck choices yielded three decision-makers subgroups. Cluster 1 (n = 27) showed a long-term advantageous strategy. Cluster 2 (n = 25) presented a maladaptive decision-making strategy. Cluster 3 (n = 62) did not develop a preference for any deck during the task. Interestingly, the proportion of participants in each cluster was not different between diagnostic groups. A Bayesian general linear model showed no credible differences in the IGT performance between diagnostic groups nor credible evidence to support the role of FPN rsFC as a biomarker of decision-making under the IGT context. This study highlights the importance of exploring in depth the behavioral and neurophysiological variables that may drive decision-making in clinical and healthy populations.

The Relationship Between Eating-Attitudes and Clinical Characteristics, Agouti-Related Peptide, and Other Biochemical Markers in Adult-Attention Deficit Hyperactivity Disorder

OBJECTIVE

In our study, we aimed to evaluate eating-attitudes in adult-ADHD, and to examine its relationship with sociodemographic, clinical, AgRP, and biochemical parameters.

METHOD

The study included 70 adult-patients and 47 healthy-controls. The DIVA2.0, SCID-1 was administered to the participants. Eating-Attitudes Test (EAT), Night-Eating Questionnaire (NEQ), Barratt Impulsivity Scale (BIS-11) were filled by the participants.

RESULTS

We found that psychological state affect eating-attitudes in adult-ADHD (p = .013), emotional eating is more common, nocturnal chronotype is dominant (p < .001), NES is more frequent (p < .001), waist circumference measurement is higher (p = .030), and lipid profile is deteriorated (p < .001). AgRP levels were significantly lower in patients treated with methylphenidate (p = .021). Those who received methylphenidate treatment had less NES than those who did not. Deterioration in eating-attitudes and symptom severity of night eating in ADHD, it was positively correlated with clinical severity of ADHD and impulsivity. In addition, age and increase in night eating symptoms were predictors of deterioration in eating attitudes in adult-ADHD. We found that impaired eating-attitudes and impulsivity severity were also predictors of NES (p = .006, p = .034).

CONCLUSION

The necessity of adult-ADHD treatment has been demonstrated by the deterioration in eating-attitudes and cardiometabolic risk dimensions and the underlying mechanisms.

Introducing an adolescent cognitive maturity index

Children show substantial variation in the rate of physical, cognitive, and social maturation as they traverse adolescence and enter adulthood. Differences in developmental paths are thought to underlie individual differences in later life outcomes, however, there remains a lack of consensus on the normative trajectory of cognitive maturation in adolescence. To address this problem, we derive a Cognitive Maturity Index (CMI), to estimate the difference between chronological and cognitive age predicted with latent factor estimates of inhibitory control, risky decision-making and emotional processing measured with standard neuropsychological instruments. One hundred and forty-one children from the Adolescent Development Study (ADS) were followed longitudinally across three time points from ages 11-14, 13-16, and 14-18. Age prediction with latent factor estimates of cognitive skills approximated age within ±10 months (r = 0.71). Males in advanced puberty displayed lower cognitive maturity relative to peers of the same age; manifesting as weaker inhibitory control, greater risk-taking, desensitization to negative affect, and poor recognition of positive affect.

Inhibitory Control Development: A Network Neuroscience Perspective

As one of the core executive functions, inhibition plays an important role in human life through development. Inhibitory control is defined as the ability to suppress actions when they are unlikely to accomplish valuable results. Contemporary neuroscience has investigated the underlying neural mechanisms of inhibitory control. The controversy started to arise, which resulted in two schools of thought: a modulatory and a network account of inhibitory control. In this systematic review, we survey developmental mechanisms in inhibitory control as well as neurodevelopmental diseases related to inhibitory dysfunctions. This evidence stands against the modulatory perspective of inhibitory control: the development of inhibitory control does not depend on a dedicated region such as the right inferior frontal gyrus (rIFG) but relies on a more broadly distributed network.

Are correlations among behavioral decision making tasks moderated by simulated cognitive impairment?

Behavioral decision making tasks are common in research settings, with only the Iowa Gambling Task available for clinical assessments. However, correlations among these tasks are low, indicating each may assess a distinct component of decision making. In addition, it is unclear whether these tasks are sensitive to invalid performance or even simulated impairment. The present study examined relationships among decision making tasks and whether simulated impairment moderates the relationships among them. Across two studies (Study 1: n = 166, Study 2: n = 130), undergraduate student participants were asked to try their best or to simulate a specific diagnosis (Attention-Deficit/Hyperactivity Disorder; Study 1), decision making impairment (Study 2), or general cognitive impairment (Study 2). They then completed a battery of tests including embedded and standalone performance validity tests (PVTs) and three behavioral decision making tasks. Across studies, participants simulating impairment were not distinguishable from controls on any of the behavioral tasks. Few significant correlations emerged among tasks across studies and the pattern of relationships between tasks did not differ on the basis of simulator or PVT failure status. Collectively, our findings suggest that these tasks may not be vulnerable to simulated cognitive impairment, and that the tasks measure largely non-overlapping aspects of decision making.

The Effects of Cognitive-Affective Switching With Unpredictable Cues in Adults and Adolescents and Their Relation to "Cool" Executive Functioning and Emotion Regulation

The impact of emotion on executive functioning is gaining interest. It has led to the differentiation of "cool" Executive Functioning (EF) processes, such as cognitive flexibility, and "hot" EF processes, such as affective flexibility. But how does affective flexibility, the ability to switch between cognitive and affective information, vary as a function of age and sex? How does this construct relate to "cool" executive functioning and cognitive-emotion regulation processes? In this study, 266 participants, including 91 adolescents (M = 16.08, SD = 1.42 years old) and 175 adults (M = 25.69, SD = 2.17 years old), completed a cognitive-affective switching task with specific (as opposed to general) unpredictable switches, as well as measures of inhibition, attention, and cognitive-emotion coping strategies. We expected cognitive to affective switching to be more costly than affective to cognitive switching in females versus males, as well as higher switch costs in adolescents. Using linear mixed modelling, we analysed the effect of age, sex, and types of switching on reaction time. Results show that adolescents are slower switchers than adults, and demonstrate that females, although faster switchers than males, are slower when switching from cognitive to affective content than when they are switching from affective to cognitive content. Multiple regression analyses revealed age-specific associations between cognitive-affective switching and inhibition. These results converge with reported developmental and gender specificities in EF and emotion processing, respectively. Additionally, affective flexibility could relate to differences in vigilance and inhibition.

OUP accepted manuscript

Objective

Attention, inhibition, and processing speed are related to functional decline among older adults. This study attempts to clarify the relationships between these cognitive factors and adaptive functioning.

Method

We examined relationships between attention, inhibition, and processing speed, with scores on the Texas Functional Living Scale (TFLS), a performance-based measure of daily functioning, in a mixed clinical sample of 530 older adults who were referred for an outpatient neuropsychological evaluation.

Results

The current study used a confirmatory factor analysis (CFA) to derive a three-factor cognitive model consisting of attention, inhibition, and processing speed. Results from a hierarchical regression, which included factor scores from the CFA, revealed that processing speed was the only significant predictor of TFLS performance when all three cognitive factors were included within a single model.

Conclusion

These results highlight the influence of processing speed as an important indicator of functional decline among a clinical population of older adults.

The role of neuropsychological assessment in adults with attention deficit/hyperactivity disorders

Attention-Deficit Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder characterized by inattention, hyperactivity and/or impulsivity. While ADHD was initially recognized as a childhood syndrome, scientific evidence accumulated to indicate that a significant proportion of ADHD children continue to experience symptoms of ADHD in adulthood. Moreover, the question of ADHD diagnosis can arise in adult patients who were not diagnosed in childhood. Currently, the diagnosis of ADHD in adulthood is based on the revised criteria described for children. However, their application for adults may be difficult for many reasons including compensation and comorbid disorders. To date, no clinical, neuropsychological, biological or imaging marker is available for the diagnosis of ADHD. Considering that ADHD is based on a neuropsychological model, in this article we will examine the usefulness of neuropsychological testing in the diagnosis in adults. We will first present diagnostic criteria of ADHD and the limits of their application in adults. We will then detail the neuropsychological data available in adult ADHD and the French and international clinical recommendations for neuropsychological assessment. Finally, we will explore the predictive value of neuropsychological scores in the diagnosis of ADHD and discuss key methodological points and perspectives for clinical research.

Impulsivity as an Endophenotype in ADHD: Negative Findings

Impulsivity has a strong genetic component and is considered an endophenotype in many psychiatric disorders. Impulsivity in adult ADHD has become a focus of interest more recently because of its suggested prominence in this age. Objective: This study aimed to access self-reported impulsivity levels in biological parents of ADHD offspring, according to their status: non-ADHD (controls), remitted, nonremitted. Method: Impulsivity levels of 155 parents of ADHD children were compared according to their status using the Barratt Impulsiveness Scale (BIS-11). Results: The ADHD group presented the highest levels of impulsivity compared with all other groups. The remitted ADHD and control groups showed no significant differences in impulsivity levels. Conclusion: Impulsivity tended to remit alongside ADHD symptoms in remitters and to persist in those presenting with the residual form of adult ADHD suggesting it should not be considered as an endophenotype. Only the attentional dimension was impaired, cautioning against Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) impulsivity proposed criteria.

Decision-Making Deficits in ADHD Are Not Related to Risk Seeking But to Suboptimal Decision-Making: Meta-Analytical and Novel Experimental Evidence

Objective: ADHD is related to decision-making deficits in real-life (e.g., substance abuse) and on experimental tasks (increased preference for risky options). In most tasks, risk and expected value are confounded (risky options have lowest expected value), making it impossible to disentangle risky from suboptimal (i.e., not choosing highest expected value) decision-making. We differentiated between risky and suboptimal decision-making in ADHD in two studies. Method and Results: First, on a multilevel meta-regression analysis (k = 48, n_ADHD = 1,144, n_Control = 1,108), ADHD and controls differed if the risky option was suboptimal (ADHD choosing more risky/suboptimal), whereas groups performed similar if the risky option was not suboptimal. Second, an empirical study showed that adults with ADHD (n = 40) made more suboptimal, but not more risky choices than controls (n = 40). Conclusion: These results contribute to a growing body of evidence that decision-making deficits in ADHD are driven by suboptimal decision-making and not by risk seeking.

Neurocognitive Functions in Bipolar Disorder in Relation to Comorbid ADHD

Introduction

Bipolar disorder (BD) and attention deficit hyperactivity disorder (ADHD) often co-occur in adult population. Both conditions present various neurocognitive and behavioral problems. We aimed to examine neurocognitive functions in adult patients with comorbid BD and ADHD (BD+ADHD) in comparison to patients with only BD, only ADHD and healthy controls (HCs).

Method

An extensive cognitive battery which evaluates verbal learning and memory, visual memory, processing speed, attention, executive functions, working memory and verbal fluency, was used to assess neurocognitive functions respectively in adult (age 18-65 years) patients with BD (n=37), ADHD (n=43), BD+ADHD (n=20) in comparison to HCs (n=51). The Multivariate Analysis of Covariance models, where age, level of education and total BIS-11 scores were included as covariates, were used for comparing neurocognitive scores among groups.

Results

Both BD and BD+ADHD groups showed significantly poorer performance than HCs in processing speed, attention, executive functions, and verbal fluency domains. The BD group had additional significant deficits in executive functions, verbal learning and memory domains. There were no significant differences between BD and BD+ADHD groups with regards to verbal learning and memory, visual memory, processing speed, attention, executive functions, working memory and verbal fluency domains. Patients with only ADHD showed significantly poorer performance than HCs in verbal fluency domain.

Conclusions

Our results show similarities in the neurocognitive functions of adults with BD and BD+ADHD across a wide range of cognitive domains. The findings point to the need for further exploration of diverging and converging neurodevelopmental trajectories of BD and ADHD.

Psychiatric Disorders and Cannabinoid Receptors

With the increasing global use of medical and adult recreational use of cannabis and cannabinoids, this chapter provides overview of evidence from animal and human studies on psychiatric disorders and cannabinoid receptors. We review and present evaluation of the relationship between changes in the ECS and psychiatric disorders. Evidence suggests the existence of a relationship between changes in components of the ECS, and some of the symptoms present in psychiatric disorders. Both CB1Rs and CB2Rs are components of the endocannabinoid system with different cellular and tissue localization patterns that are differentially expressed in the CNS and PNS and are emerging targets for the treatment of number psychiatric disorders. As cannabis preparations are widely used for recreation globally, it is predictable that cannabis use disorders (CUDs) will increase and there is currently no available treatment for CUDs. Although major advances have been reported from cannabinoid and ECS research, there are gaps in scientific knowledge on long-term consequences of cannabis use. Adolescent and cannabis use during pregnancy presents further challenges, and more research will uncover the signaling pathways that couple the gut microbiota with the host ECS. Development of cannabis and cannabinoid nanomedicine for nanotherapy will certainly overcome some of the shortcomings and challenges in medicinal and recreational use of cannabis and cannabinoids. Thus, nanotechnology will allow targeted delivery of cannabinoid formulations with the potential to elevate their use to scientifically validated nanotherapeutic applications as the field of cannabis nanoscience matures.

Trait impulsivity in Juvenile Myoclonic Epilepsy

Objective

Impulsivity is a multidimensional construct that can predispose to psychopathology. Meta‐analysis demonstrates an association between response impulsivity and Juvenile Myoclonic Epilepsy (JME), a common genetic generalized epilepsy. Here, we test the hypotheses that trait impulsivity is (i) elevated in JME compared to controls; (ii) moderated by specific seizure characteristics; and (iii) associated with psychiatric adverse effects of antiepileptic drugs (AEDs).

Methods

322 participants with JME and 126 age and gender‐matched controls completed the Barratt’s Impulsiveness Scale (BIS‐brief) alongside information on seizure history and AED use. We compared group BIS‐brief scores and assessed associations of JME BIS‐brief scores with seizure characteristics and AED adverse effects.

Results

The mean BIS‐brief score in JME was 18.1 ± 4.4 compared with 16.2 ± 4.1 in controls (P = 0.0007). Elevated impulsivity was associated with male gender (P = 0.027), frequent absence seizures (P = 0.0004) and lack of morning predominance of myoclonus (P = 0.008). High impulsivity significantly increased the odds of a psychiatric adverse event on levetiracetam (P = 0.036), but not any other psychiatric or somatic adverse effects.

Interpretation

Trait impulsivity is elevated in JME and comparable to scores in personality and neurotic disorders. Increased seizure frequency and absence of circadian seizure pattern moderate BIS score, suggesting disruption of both cortico‐striatal and thalamocortical networks as a shared mechanism between seizures and impulsivity in JME. These findings warrant consideration of impulsivity as a distinct target of intervention, and as a stratifying factor for AED treatment in JME, and perhaps other types of epilepsy. The role of impulsivity in treatment adherence and psychosocial outcome requires further investigation.

Impaired working memory, cognitive flexibility and reward processing in mice genetically lacking Gpr88: Evidence for a key role for Gpr88 in multiple cortico-striatal-thalamic circuits

The GPR88 orphan G protein-coupled receptor is expressed throughout the striatum, being preferentially localised in medium spiny neurons. It is also present in lower densities in frontal cortex and thalamus. Rare mutations in humans suggest a role in cognition and motor function, while common variants are associated with psychosis. Here we evaluate the influence of genetic deletion of GPR88 upon performance in translational tasks interrogating motivation, reward evaluation and cognitive function. In an automated radial arm maze 'N-back' working memory task, Gpr88 KO mice showed impaired correct responding, suggesting a role for GPR88 receptors in working memory circuitry. Associative learning performance was similar to wild-type controls in a touchscreen task but performance was impaired at the reversal learning stage, suggesting cognitive inflexibility. Gpr88 KO mice showed higher breakpoints, reduced latencies and lengthened session time in a progressive ratio task consistent with enhanced motivation. Simultaneously, locomotor hyperactivity was apparent in this task, supporting previous findings of actions of GPR88 in a cortico-striatal-thalamic motor loop. Evidence for a role of GPR88 in reward processing was demonstrated in a touchscreen-based equivalent of the Iowa gambling task. Although both Gpr88 KO and wild-type mice showed a preference for an optimum contingency choice, Gpr88 KO mice selected more risky choices at the expense of more advantageous lower risk options. Together these novel data suggest that striatal GPR88 receptors influence activity in a range of procedures integrated by prefrontal, orbitofrontal and anterior cingulate cortico-striatal-thalamic loops leading to altered cognitive, motivational and reward evaluation processes.

The Clinical Characteristics of ADHD and Obsessive-Compulsive Disorder Comorbidity

Objective: To investigate the clinical implications of obsessive-compulsive disorder (OCD) and ADHD comorbidity in adults. Method: The OCD patients who had and had no diagnosis of adulthood ADHD were compared in terms of several demographic and clinical variables. Results: The mean number of obsessions and compulsions; hoarding, symmetry, and miscellaneous obsessions; ordering/arranging and hoarding compulsions; total, attentional, and motor subscale scores of Barratt Impulsivity Scale (BIS)-11 were more frequent among the patients with OCD-ADHD. The mean age of onset was more likely to be earlier in ADHD-OCD group than in OCD group. Impulsivity, symmetry obsessions, and hoarding compulsions strongly predicted the coexistence between ADHD and OCD. Conclusion: OCD-ADHD comorbidity in adults seemed to be associated with an earlier onset of OCD, with the predominance of impulsivity, and with a different obsessive-compulsive symptom (OC) profile from OCD patients without a diagnosis of ADHD.

Does ADHD Symptomatology Influence Treatment Outcome and Dropout Risk in Eating Disorders? A longitudinal Study

Attention-deficit/hyperactivity disorder (ADHD) and its symptoms have been shown to be present in patients with eating disorders (EDs) and are associated with increased psychopathology and more dysfunctional personality traits. This study aimed to assess if the presence of ADHD symptoms in patients with EDs affects their short and long-term therapy outcome. A total of 136 consecutively treated ED patients were considered in this study. Baseline pre-treatment evaluation included the Adult ADHD Self-Report Scale (ASRS v1.1) for ADHD symptoms and the assessment of eating symptomatology using the Eating Disorders Inventory (EDI-2). Treatment outcome was evaluated in terms of ED symptoms after cognitive behavioral therapy (CBT) and dropout rate during treatment. Furthermore, we evaluated ED symptoms in treatment completers after a follow-up of 8 years on average. Path analyses assessed the potential mediational role of the EDI-2 total score in the relationship between ADHD and treatment outcome. Results showed that baseline symptoms of ADHD indirectly affected treatment outcome after CBT; the ASRS positive screening was related to higher eating symptomatology (standardized coefficient B = 0.41, p = 0.001, 95% CI: 0.26 to 0.55), and the presence of high ED levels contributed to the increase of dropout (B = 0.15, p = 0.041, 95% CI: 0.03 to 0.33) and a worse treatment outcome (B = 0.18, p = 0.041, 95% CI: 0.01 to 0.35). No direct effect was found between the ASRS positive screening with the risk of dropout (B = -0.08, p = 0.375) and worse treatment outcome (B = -0.07, p = 0.414). These results suggest the relevance of identifying specific treatment approaches for patients with ADHD symptoms and severe eating symptomatology.

Cognitive deficits in methamphetamine addiction: Independent contributions of dependence and intelligence

BACKGROUND

Methamphetamine's effects on brain function have been associated with cognitive deficits, which have a negative impact on clinical outcomes. However, it remains unclear if cognitive deficits relate to methamphetamine dependence (potentially amenable to abstinence and retraining) or background characteristics, mental health and other drug use. We tested the association between methamphetamine dependence and cognitive performance, while factoring in the impact of background characteristics, depressive symptoms and tobacco, alcohol and cannabis use.

METHOD

The sample comprised 108 treatment-seeking participants who met the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV TR) criteria for methamphetamine dependence and 50 socio-demographically matched controls. We administered a comprehensive neuropsychological test battery (delay discounting, decision making, disinhibition, episodic and working memory) and examined cognitive deficits in methamphetamine users after taking into account socio-demographic characteristics, tobacco, alcohol and cannabis use, and depressive symptoms.

RESULTS

Hierarchical multiple regression analyses showed that methamphetamine dependence was associated with poorer performance in decision-making and disinhibition over and above other predictors, while IQ better explained performance in episodic and working memory. Although duration of methamphetamine use was linked to disinhibition, other patterns of methamphetamine use (including dose and frequency) were not consistently related to performance.

CONCLUSIONS

Methamphetamine dependence impacts inhibitory control and decision-making, whereas lower IQ associates with memory/working memory deficits among methamphetamine users. Findings suggest the need to target disinhibition and impulsive decision-making as part of methamphetamine dependence treatment, while buffering the impact of IQ on memory systems.

Approach and avoidance patterns in reward learning across domains: An initial examination of the Social Iowa Gambling Task

The current study examines learning patterns in response to both monetary and social incentives through both approach and avoidance behaviors using modified versions of the Iowa Gambling Task. Specifically, we investigated learning in response to both positive and negative feedback in a sample of 191 undergraduate students. The social task was a novel paradigm, and social feedback were images of faces displaying positive and negative emotions. We examined internal validity of the tasks through modeling changes in approach and avoidance. We also explored associations between approach and avoidance learning and individual differences in anxiety and social anxiety, depression and well-being, general anhedonia and social closeness, and fun-seeking, using multilevel models (MLMs). Results showed that both the monetary and social tasks demonstrated learning as shown by decreases in plays on disadvantageous decks across the task. Additionally, we found that overall task performance on the monetary task was associated with fun-seeking and overall task performance on the social task was associated with fun-seeking and depressive symptoms. Initial findings suggest promise for the novel task in the examination of social avoidance learning.

Early Attentional Modulation by Working Memory Training in Young Adult ADHD Patients during a Risky Decision-Making Task

Background: Working memory (WM) deficits and impaired decision making are among the characteristic symptoms of patients affected by attention deficit/hyperactivity disorder (ADHD). The inattention associated with the disorder is likely to be due to functional deficits of the neural networks inhibiting irrelevant sensory input. In the presence of unnecessary information, a good decisional process is impaired and ADHD patients tend to take risky decisions. This study is aimed to test the hypothesis that the level of difficulty of a WM training (WMT) is affecting the top-down modulation of the attentional processes in a probabilistic gambling task. Methods: Event-related potentials (ERP) triggered by the choice of the amount wagered in the gambling task were recorded, before and after WMT with a the dual n-back task, in young ADHD adults and matched controls. For each group of participants, randomly assigned individuals were requested to perform WMT with a fixed baseline level of difficulty. The remaining participants were trained with a performance-dependent adaptive n-level of difficulty. Results: We compared the ERP recordings before and after 20 days of WMT in each subgroup. The analysis was focused on the time windows with at least three recording sites showing differences before and after training, after Bonferroni correction ( p < 0.05 ). In ADHD, the P1 wave component was selectively affected at frontal sites and its shape was recovered close to controls' only after adaptive training. In controls, the strongest contrast was observed at parietal level with a left hemispheric dominance at latencies near 900 ms, more after baseline than after adaptive training. Conclusion: Partial restoration of early selective attentional processes in ADHD patients might occur after WMT with a high cognitive load. Modified frontal sites' activities might constitute a neural marker of this effect in a gambling task. In controls, conversely, an increase in late parietal negativity might rather be a marker of an increase in transfer effects to fluid intelligence.

Deficient Decision Making in Pathological Gamblers Correlates With Gray Matter Volume in Medial Orbitofrontal Cortex

Individuals suffering from pathological gambling (PG) show impaired decision making, but it is still not clear how this impairment is related to other traits and neuroanatomical characteristics. In this study, we investigated how the influence of PG on decision making (1) is connected to different impulsivity facets and (2) how it is related to gray matter volume (GMV) in various brain regions. Twenty-eight diagnosed PG patients and 23 healthy controls completed the cups task to measure decision making. In this task, participants had to decide between safe and risky options, which varied in expected value (EV) between risk advantageous, equal EV, and risk disadvantageous choices. A delay discounting task and the Barrant Impulsiveness Scale were applied to assess multiple impulsivity facets. In addition, structural magnetic resonance images were acquired. In comparison to the control group PG patients demonstrated more deficits in decision making, indicated by less EV sensitivity, but there was no significant difference in number of overall risky choices. Also, PG patients showed increased impulsivity in nearly every dimension. Results revealed (1) a positive correlation between decision making impairments and non-planning impulsivity but no significant relation to other impulsivity facets. Although we found no GMV differences between PG patients and controls, (2) a regions of interest analysis showed a correlation between medial orbitofrontal GMV and EV sensitivity in PG patients. Our findings showed that (1) the association between decision making and impulsivity can also be found in PG patients, but only for certain impulsivity facets. This suggests that it is essential to consider measuring different dimensions, when investigating impulsivity in a PG sample. Secondly, our findings revealed that (2) dysfunctional decision making-particularly the component of risk evaluation-is related to decreased GMV in the medial orbitofrontal cortex, a brain region concerned with processing of rewards. Interestingly, we did not find more risky choices for PG patients, and thus, we assume that decision making deficits in PG are primarily related to risk evaluation, not risk seeking, which is in line with our GMV findings.

The Structure, Measurement Invariance, and External Validity of the Barratt Impulsiveness Scale-Brief in a Sample of At-Risk Adolescents

The purpose of this study was to evaluate the factor structure and measurement invariance of the Barratt Impulsiveness Scale-Brief version (BIS-Brief) in an archival sample of 315 adolescents (81% male; 63.5% Caucasian; M_age = 16.7 years) participating in a military-style residential program for at-risk youths. Additionally, correlations between BIS scores and external measures of impulsivity-related behaviors were examined. Results showed support for a previously described two-dimensional structure for the BIS-Brief, which was invariant across racial groups. Additionally, the BIS-Brief performed similarly to the total BIS-11 score in relation to external measures of impulsivity-related behaviors. However, the two dimensions exhibited some significant differences in their associations with other measures. This study supports the utility of the BIS-Brief as a brief measure of impulsivity and suggests that the dimensions of the BIS-Brief may be useful in distinguishing how different aspects of impulsivity relate to problem behaviors such as binge drinking and self-injury.

Methylphenidate increases willingness to perform effort in adults with ADHD

BACKGROUND

A reduced willingness to perform effort based on the magnitude and probability of potential rewards has been associated with diminished dopamine function and may be relevant to attention-deficit/hyperactivity disorder (ADHD). Here, we investigated the influence of ADHD status and methylphenidate on effort-based decisions. We hypothesized that ADHD participants would make fewer high-effort selections than non-ADHD subjects, and that methylphenidate would increase the number of high-effort selections. Furthermore, we hypothesized there would be associations among ADHD severity and methylphenidate-related changes in effort-based and attentional performance across all participants.

METHODS AND PARTICIPANTS

ADHD (n = 23) and non-ADHD (n = 23) adults completed the Effort Expenditure for Rewards Task in which participants select between low-effort and high-effort options to receive monetary rewards at varying levels of reward magnitude and probability. A test of attentional performance was also completed.

RESULTS

Overall, participants made more high-effort selections as potential reward magnitude and probability increased. ADHD participants did not make fewer high-effort selections than non-ADHD participants, but ADHD participants showed greater methylphenidate-related increases in high-effort selections. ADHD participants had worse attentional performance than non-ADHD participants. ADHD severity was associated with methylphenidate-related changes in high-effort selections, but not changes in attentional performance.

CONCLUSIONS

These results indicate that methylphenidate increases the willingness to perform effort in individuals with ADHD, possibly due to disorder-related motivational deficits. This provides support for theories of insufficient effort allocation among individuals with ADHD.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier, NCT02630017.

An investigation of the effect of trauma script exposure on risk-taking among patients with substance use disorders and posttraumatic stress disorder

Studies show that patients with substance use disorders (SUD) and posttraumatic stress disorder (PTSD) are at high risk for engaging in risky behaviors. However, these studies do not speak to the context in which these behaviors are more likely to occur. This study examined whether SUD patients with current PTSD, compared to those without a history of PTSD, are more likely to exhibit risk-taking on a laboratory-based risk-taking task, the Iowa Gambling Task (IGT), following exposure to a personalized trauma script versus a neutral script. The sample consisted of 122 trauma-exposed SUD patients with and without PTSD. Participants were administered a series of diagnostic interviews and personalized trauma scripts were created. On separate days, participants were exposed to a neutral or trauma script, followed by the IGT. Contrary to expectations, PTSD-SUD patients exhibited significantly greater risk-taking after the neutral (vs. trauma) script than those without PTSD. Moreover, whereas SUD patients without PTSD evidenced stability in IGT performance across scripts, those with PTSD exhibited significantly lower risk-taking on the IGT following the trauma (vs. neutral) script. Results provide support for the context dependent nature of risk-taking in PTSD-SUD patients and suggest they may become more risk averse in the context of trauma-related distress.

Orbitofrontal dysfunction during the reward process in adults with ADHD: An fMRI study

OBJECTIVE

The present study aimed to detect differences in the reward response between adults with attention deficit hyperactivity disorder (ADHD) and healthy controls (HCs) using functional magnetic resonance imaging (fMRI).

METHODS

The Iowa gambling task (IGT) was designed to explore participants' reward-related decision-making in relation to selections during risky behaviors. Twenty adults with ADHD and 20 HCs were enrolled. fMRI with a modified IGT was performed.

RESULTS

The adults with ADHD showed a poorer performance in terms of avoidance during risky behaviors. The fMRI results indicated that the adults with ADHD had significantly lower orbitofrontal cortex (OFC) activation. A positive correlation between performance in the IGT and brain activation in the OFC was detected.

CONCLUSIONS

The results suggested that the adults with ADHD exhibited abnormal OFC responses during decision-making.

SIGNIFICANCE

To the best of our knowledge, this is the first study to use fMRI to collect brain activation data while performing the IGT in adults with ADHD. Our findings suggest that deficits in reward processing in ADHD are still present during adulthood.

Learning Process During Risk Detection in Adolescents With ADHD

OBJECTIVE

To evaluate and describe the performance during the learning process of risk-detection versus risk-benefit processing in adolescents diagnosed with ADHD.

METHOD

Thirty-five adolescents with ADHD and 26 paired controls participated. The tests applied are Iowa-type children version paradigm and Stroop test.

RESULTS

Adolescents with ADHD exhibited lower risk-benefit processing capacity and lower ability to detect risk selections; main findings also indicate that adolescents with ADHD were slower to learn to avoid risk choices. In addition, they also presented a deficient inhibitory control.

CONCLUSION

Results confirm the presence of a deficit in advantageous choice in adolescents with ADHD. By providing a measure of risk choice-and not only a net score-we show that adolescents with ADHD also fail to avoid risk choices. This deficit is mainly because they are slower in learning how to avoid risk choices, and not simply deficient. Literature is scarce concerning studies with Iowa-type paradigms in samples intregated exclusively by adolescents. More research is needed to clarify the nature of these deficiencies.

Response Patterns to Emotional Faces Among Adolescents Diagnosed With ADHD

OBJECTIVE

The present study investigated differences in emotional face processing between adolescents (age 15-18) with ADHD-Combined type (ADHD-CT) and typically developing controls.

METHOD

Participants completed a visual emotional task in which they were asked to rate the degree of negativity/positivity of four facial expressions (taken from the NimStim face stimulus set).

RESULTS

Participants' ratings, ratings' variability, response times (RTs), and RTs' variability were analyzed. Results showed a significant interaction between group and the type of presented stimuli. Adolescents with ADHD-CT discriminated less between positive and negative emotional expressions compared with those without ADHD. In addition, adolescents with ADHD-CT exhibited greater variability in their RTs and in their ratings of facial expressions when compared with controls.

CONCLUSION

The present results lend further support to the existence of a specific deficit or alteration in the processing of emotional face stimuli among adolescents with ADHD-CT.

Transcranial direct current brain stimulation decreases impulsivity in ADHD

BACKGROUND

Impulsivity is a core deficit in attention deficit hyperactivity disorder (ADHD). Transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) has been shown to modulate cognitive control circuits and could enhance DLPFC activity, leading to improved impulse control in ADHD.

OBJECTIVE

Hypothesis: We predicted 2.0 mA anodal stimulation (tDCS) versus sham stimulation applied over the left DLPFC would improve Conners Continuous Performance Task (CPT) scores. Our secondary hypothesis predicted that stop signal task (SST) reaction time (SSRT) would decrease with tDCS (versus sham).

METHODS

Thirty-seven participants completed two periods of three tDCS (or sham) sessions two weeks apart in a within-subject, double-blind, counterbalanced order. Participants performed a fractal N-back training task concurrent with tDCS (or sham) stimulation. Participants completed the CPT and SST at the beginning of treatment (baseline), at the end of the treatment, and at a 3-day post-stimulation follow-up.

RESULTS

There was a significant stimulation condition by session interaction for CPT false positive scores (χ² = 15.44, p < 0.001) driven by a decrease in false positive errors from baseline to end of treatment in the tDCS group (β = -0.36, 95% Confidence Interval (CI) -0.54 to -0.18, p < 0.001). This effect did not persist at follow-up (β = -0.13, p > 0.05). There was no significant stimulation condition by session interaction effect on CPT true positive errors or response time (ps > 0.05). No significant change in SSRT performance was observed (p > 0.05).

CONCLUSION

These findings suggest that stimulation of the left DLPFC with tDCS can improve impulsivity symptoms in ADHD, supporting the therapeutic potential for tDCS in adult ADHD patients.

Impulsivity predicts poorer improvement in quality of life during early treatment for people with methamphetamine dependence

BACKGROUND AND AIMS

Methamphetamine dependence is associated with heightened impulsivity and diminished quality of life, but the link between impulsivity and changes in quality of life during treatment has not been examined. We aimed to investigate how different elements of impulsivity predict change in quality of life in the 6 weeks after engaging in treatment.

DESIGN

Longitudinal, observational cohort study.

SETTING

Public and private detoxification and rehabilitation facilities in metropolitan Melbourne, Australia.

PARTICIPANTS

One hundred and eight individuals with methamphetamine dependence (81 male) tested within 3 weeks of commencing treatment; 80 (74%) were followed-up at 6 weeks.

MEASUREMENTS

The Continuous Performance Test-2 measured impulsive action (cognitive and motor impulsivity); the Delay Discounting Task measured impulsive choice. Quality of life was measured with the World Health Organization Quality of Life Scale-Brief, which includes social, psychological, physical and environment domains. Control variables included age, gender, estimated IQ, depression severity score, methamphetamine dependence severity score, cannabis dependence severity score and treatment modality.

FINDINGS

We found that all three forms of impulsivity were significant predictors of change in the social domain: motor impulsivity (β = -0.54, P = 0.013), cognitive impulsivity (β = -0.46, P = 0.029) and impulsive choice (β = -0.26, P = 0.019). Change in the psychological domain was predicted significantly by motor impulsivity (β = -0.45, P = 0.046). Control variables of age and depression were associated significantly with changes in the physical domain.

CONCLUSIONS

In Australian methamphetamine-dependent individuals, elevated impulsivity predicts lower improvement of social and psychological quality of life in the first 6-9 weeks of treatment.

Latent traits of impulsivity and compulsivity: toward dimensional psychiatry

BACKGROUND

The concepts of impulsivity and compulsivity are commonly used in psychiatry. Little is known about whether different manifest measures of impulsivity and compulsivity (behavior, personality, and cognition) map onto underlying latent traits; and if so, their inter-relationship.

METHODS

A total of 576 adults were recruited using media advertisements. Psychopathological, personality, and cognitive measures of impulsivity and compulsivity were completed. Confirmatory factor analysis was used to identify the optimal model.

RESULTS

The data were best explained by a two-factor model, corresponding to latent traits of impulsivity and compulsivity, respectively, which were positively correlated with each other. This model was statistically superior to the alternative models of their being one underlying factor ('disinhibition') or two anticorrelated factors. Higher scores on the impulsive and compulsive latent factors were each significantly associated with worse quality of life (both p < 0.0001).

CONCLUSIONS

This study supports the existence of latent functionally impairing dimensional forms of impulsivity and compulsivity, which are positively correlated. Future work should examine the neurobiological and neurochemical underpinnings of these latent traits; and explore whether they can be used as candidate treatment targets. The findings have implications for diagnostic classification systems, suggesting that combining categorical and dimensional approaches may be valuable and clinically relevant.

Amphetamine Modestly Improves Conners' Continuous Performance Test Performance in Healthy Adults

OBJECTIVES

Amphetamine improves vigilance as assessed by continuous performance tests (CPT) in children and adults with attention deficit hyperactivity disorder (ADHD). Less is known, however, regarding amphetamine effects on vigilance in healthy adults. Thus, it remains unclear whether amphetamine produces general enhancement of vigilance or if these effects are constrained to the remediation of deficits in patients with ADHD.

METHODS

We tested 69 healthy adults (35 female) on a standardized CPT (Conner's CPT-2) after receiving 10- or 20-mg d-amphetamine or placebo. To evaluate potential effects on learning, impulsivity, and perseveration, participants were additionally tested on the Iowa Gambling Task (IGT) and Wisconsin Card Sorting Task (WCST).

RESULTS

Participants receiving placebo exhibited the classic vigilance decrement, demonstrated by a significant reduction in attention (D') across the task. This vigilance decrement was not observed, however, after either dose of amphetamine. Consistent with enhanced vigilance, the 20-mg dose also reduced reaction time variability across the task and the ADHD confidence index. The effects of amphetamine appeared to be selective to vigilance since no effects were observed on the IGT, WCST, or response inhibition/perseveration measures from the CPT.

CONCLUSIONS

The present data support the premise that amphetamine improves vigilance irrespective of disease state. Given that amphetamine is a norepinephrine/dopamine transporter inhibitor and releaser, these effects are informative regarding the neurobiological substrates of attentional control. (JINS, 2018, 24, 283-293).

Monoamine Oxidase-A Genetic Variants and Childhood Abuse Predict Impulsiveness in Borderline Personality Disorder

Objective

Impulsivity is a core feature of borderline personality disorder (BPD) and antisocial personality disorder (ASPD) that likely arises from combined genetic and environmental influences. The interaction of the low activity variant of the monoamine oxidase-A (MAOA-L) gene and early childhood adversity has been shown to predict aggression in clinical and non-clinical populations. Although impulsivity is a risk factor for aggression in BPD and ASPD, little research has investigated potential gene-environment (G×E) influences impacting its expression in these conditions. Moreover, G×E interactions may differ by diagnosis.

Methods

Full factorial analysis of variance was employed to investigate the influence of monoamine oxidase-A (MAO-A) genotype, childhood abuse, and diagnosis on Barratt Impulsiveness Scale-11 (BIS-11) scores in 61 individuals: 20 subjects with BPD, 18 subjects with ASPD, and 23 healthy controls.

Results

A group×genotype×abuse interaction was present (F(2,49)=4.4, p=0.018), such that the interaction of MAOA-L and childhood abuse predicted greater BIS-11 motor impulsiveness in BPD. Additionally, BPD subjects reported higher BIS-11 attentional impulsiveness versus ASPD participants (t(1,36)=2.3, p=0.025).

Conclusion

These preliminary results suggest that MAOA-L may modulate the impact of childhood abuse on impulsivity in BPD. Results additionally indicate that impulsiveness may be expressed differently in BPD and ASPD.

Translation, Adaptation, and Validation of the Brazilian Version of the Dickman Impulsivity Inventory (Br-DII)

Impulsivity has mainly been described as a negative or dysfunctional characteristic associated with several disorders. However, impulsivity is not only related to dysfunctional outcomes and may explain individual differences in optimal human functioning as well. The Dickman Impulsivity Inventory (DII) is a self-report instrument measuring both the dysfunctional and the functional aspects of impulsivity. In this study, we performed the translation and cultural adaptation of the DII to the Brazilian context and analyzed its psychometric properties. Translation and cultural adaptation followed a rigorous process, which relied on an expert panel in the cross-cultural adaptation of psychological instruments. Data from 405 undergraduate students were obtained for the Brazilian version of the DII (Br-DII). The 23 items of the Br-DII was considered unsuitable according to model fit indices of the Confirmatory Factor Analysis (both for Oblique and Orthogonal models). Exploratory Factor Analysis showed an 18 items version of the Br-DII to be suitable (CFI = 0.92; TLI = 0.90, and RMSEA = 0.057). The DII's 18 items version also showed adequate Cronbach's alpha, intraclass correlation coefficient, and convergent and discriminant validity with the BIS-11. Therefore, the Br-DII demonstrated reliability and validity in the measurement of functional and dysfunctional impulsivity.

Chronic atomoxetine treatment during adolescence does not influence decision-making on a rodent gambling task, but does modulate amphetamine's effect on impulsive action in adulthood

In addition to the symptoms of inattention, hyperactivity, and impulsivity, individuals with attention deficit hyperactivity disorder exhibit impaired performance on tests of real-world cost/benefit decision-making. Atomoxetine, a nonstimulant drug approved for the treatment of attention deficit hyperactivity disorder, is a selective norepinephrine reuptake inhibitor administered chronically during adolescence, a time during which the frontal brain regions necessary for executive function undergo extensive maturation. This treatment protocol can affect behavior well into adulthood, but whether it produces long-term changes in complex decision-making has not been investigated. Twenty-four Long-Evans rats were administered saline or 1.0 mg/kg atomoxetine daily from postnatal day 40 to 54. Two weeks after treatment, the adult rats were trained and assessed on the rodent gambling task, in which the animals chose from four options varying in reward, punishment, and uncertainty. Impulsive action was also measured by recording the number of premature responses made. Regardless of the treatment administered during adolescence, rats learned to favor the advantageous options characterized by small, low-penalty rewards in lieu of the larger, higher-penalty reward options. Rodent gambling task performance was then assessed following acute treatment with atomoxetine (0.1-1.0 mg/kg) and amphetamine (0.3-1.5 mg/kg). Across groups, the highest dose of atomoxetine impaired decision-making and decreased premature responding at all doses tested. Amphetamine also impaired choice performance, but selectively increased impulsive action in rats that had previously received atomoxetine treatment during adolescence. These findings contribute to our understanding of the long-term effects associated with chronic adolescent atomoxetine exposure and suggest that this treatment does not alter decision-making under conditions of risk and uncertainty in adulthood.

Difference in Perseverative Errors during a Visual Attention Task with Auditory Distractors in Alpha-9 Nicotinic Receptor Subunit Wild Type and Knock-Out Mice

The auditory efferent system is a neural network that originates in the auditory cortex and projects to the cochlear receptor through olivocochlear (OC) neurons. Medial OC neurons make cholinergic synapses with outer hair cells (OHCs) through nicotinic receptors constituted by α9 and α10 subunits. One of the physiological functions of the α9 nicotinic receptor subunit (α9-nAChR) is the suppression of auditory distractors during selective attention to visual stimuli. In a recent study we demonstrated that the behavioral performance of alpha-9 nicotinic receptor knock-out (KO) mice is altered during selective attention to visual stimuli with auditory distractors since they made less correct responses and more omissions than wild type (WT) mice. As the inhibition of the behavioral responses to irrelevant stimuli is an important mechanism of the selective attention processes, behavioral errors are relevant measures that can reflect altered inhibitory control. Errors produced during a cued attention task can be classified as premature, target and perseverative errors. Perseverative responses can be considered as an inability to inhibit the repetition of an action already planned, while premature responses can be considered as an index of the ability to wait or retain an action. Here, we studied premature, target and perseverative errors during a visual attention task with auditory distractors in WT and KO mice. We found that α9-KO mice make fewer perseverative errors with longer latencies than WT mice in the presence of auditory distractors. In addition, although we found no significant difference in the number of target error between genotypes, KO mice made more short-latency target errors than WT mice during the presentation of auditory distractors. The fewer perseverative error made by α9-KO mice could be explained by a reduced motivation for reward and an increased impulsivity during decision making with auditory distraction in KO mice.

Striatal GPR88 Modulates Foraging Efficiency

The striatum is anatomically and behaviorally implicated in behaviors that promote efficient foraging. To investigate this function, we studied instrumental choice behavior in mice lacking GPR88, a striatum-enriched orphan G-protein-coupled receptor that modulates striatal medium spiny neuron excitability. Our results reveal that hungry mice lacking GPR88 (KO mice) were slow to acquire food-reinforced lever press but could lever press similar to controls on a progressive ratio schedule. Both WT and KO mice discriminated between reward and no-reward levers; however, KO mice failed to discriminate based on relative quantity-reward (1 vs 3 food pellets) or effort (3 vs 9 lever presses). We also demonstrate preference for the high-reward (3 pellet) lever was selectively reestablished when GPR88 expression was restored to the striatum. We propose that GPR88 expression within the striatum is integral to efficient action-selection during foraging.SIGNIFICANCE STATEMENT Evolutionary pressure driving energy homeostasis favored detection and comparison of caloric value. In wild and laboratory settings, neural systems involved in energy homeostasis bias foraging to maximize energy efficiency. This is observed when foraging behaviors are guided by superior nutritional density or minimized caloric expenditure. The striatum is anatomically and functionally well placed to perform the sensory and motor integration necessary for efficient action selection during foraging. However, few studies have examined this behavioral phenomenon or elucidated underlying molecular mechanisms. Both humans and mice with nonfunctional GPR88 have been shown to present striatal dysfunctions and impaired learning. We demonstrate that GPR88 expression is necessary to efficiently integrate effort and energy density information guiding instrumental choice.

Shared and disorder-specific task-positive and default mode network dysfunctions during sustained attention in paediatric Attention-Deficit/Hyperactivity Disorder and obsessive/compulsive disorder

Patients with Attention-Deficit/Hyperactivity Disorder (ADHD) and obsessive/compulsive disorder (OCD) share problems with sustained attention, and are proposed to share deficits in switching between default mode and task positive networks. The aim of this study was to investigate shared and disorder-specific brain activation abnormalities during sustained attention in the two disorders. Twenty boys with ADHD, 20 boys with OCD and 20 age-matched healthy controls aged between 12 and 18 years completed a functional magnetic resonance imaging (fMRI) version of a parametrically modulated sustained attention task with a progressively increasing sustained attention load. Performance and brain activation were compared between groups. Only ADHD patients were impaired in performance. Group by sustained attention load interaction effects showed that OCD patients had disorder-specific middle anterior cingulate underactivation relative to controls and ADHD patients, while ADHD patients showed disorder-specific underactivation in left dorsolateral prefrontal cortex/dorsal inferior frontal gyrus (IFG). ADHD and OCD patients shared left insula/ventral IFG underactivation and increased activation in posterior default mode network relative to controls, but had disorder-specific overactivation in anterior default mode regions, in dorsal anterior cingulate for ADHD and in anterior ventromedial prefrontal cortex for OCD. In sum, ADHD and OCD patients showed mostly disorder-specific patterns of brain abnormalities in both task positive salience/ventral attention networks with lateral frontal deficits in ADHD and middle ACC deficits in OCD, as well as in their deactivation patterns in medial frontal DMN regions. The findings suggest that attention performance in the two disorders is underpinned by disorder-specific activation patterns.

Logical fallacies in animal model research

Background

Animal models of human behavioural deficits involve conducting experiments on animals with the hope of gaining new knowledge that can be applied to humans. This paper aims to address risks, biases, and fallacies associated with drawing conclusions when conducting experiments on animals, with focus on animal models of mental illness.

Conclusions

Researchers using animal models are susceptible to a fallacy known as false analogy, where inferences based on assumptions of similarities between animals and humans can potentially lead to an incorrect conclusion. There is also a risk of false positive results when evaluating the validity of a putative animal model, particularly if the experiment is not conducted double-blind. It is further argued that animal model experiments are reconstructions of human experiments, and not replications per se, because the animals cannot follow instructions. This leads to an experimental setup that is altered to accommodate the animals, and typically involves a smaller sample size than a human experiment. Researchers on animal models of human behaviour should increase focus on mechanistic validity in order to ensure that the underlying causal mechanisms driving the behaviour are the same, as relying on face validity makes the model susceptible to logical fallacies and a higher risk of Type 1 errors. We discuss measures to reduce bias and risk of making logical fallacies in animal research, and provide a guideline that researchers can follow to increase the rigour of their experiments.

ADHD symptoms in non-treatment seeking young adults: relationship with other forms of impulsivity

OBJECTIVE

Attention-deficit hyperactivity disorder (ADHD) has been associated with various manifestations of impulsivity in adults, including elevated rates of other impulsive disorders, substance use, questionnaire-based impulsivity scores, and inhibitory dysregulation on neurocognitive tests. The relationship between ADHD and all these other forms of impulsivity has yet to be explored within the context of a single comprehensive study.

METHODS

A total of 423 young adults, who gambled ≥5 times in the preceding year, were recruited using media advertisements and undertook detailed assessment including structured psychiatric interview, questionnaires, and neurocognitive tests. Participants with ADHD symptoms were identified using the Adult ADHD Self-Report Scale Screener (ASRS-V1.1) and were compared to controls using multivariate analysis of variance (MANOVA).

RESULTS

ADHD symptoms were found in 20.3% of the sample, but only 7.3% of these subjects had ever received a formal diagnosis. ADHD symptoms were associated with significantly lower quality of life, lower self-esteem, higher emotional dysregulation, higher impulsivity questionnaire scores, more problematic Internet use, greater occurrence of psychiatric disorders, and impaired stop-signal reaction times. Of these variables, stop-signal reaction times and Barratt attentional impulsiveness were the strongest predictors of group classification.

CONCLUSIONS

ADHD symptoms are common and under-diagnosed in young adults who gamble, and are most strongly linked with certain other types of impulsivity (questionnaire- and cognitive-based measures) and with emotional dysregulation, suggesting that these are each important considerations in understanding the pathophysiology of the disorder, but also potential treatment targets. It is necessary to question whether treatment for adult ADHD could be enhanced by considering self-esteem, emotional reactivity, and impaired inhibitory control as specific treatment targets, in addition to the core diagnostic symptoms of the disorder.