Impaired extra-dimensional shift performance in medicated and unmedicated Parkinson's disease: evidence for a specific attentional dysfunction

Gene Therapy Targeting GD3 Synthase Protects Against MPTP-Induced Parkinsonism and Executive Dysfunction

More than half of Parkinson's patients exhibit fronto-striatally mediated executive dysfunction, including deficits in sustained attention, judgment, and impulse control. We have previously shown that modification of brain gangliosides by targeted deletion of GD3 synthase (GD3S) is neuroprotective in vivo and in vitro. The objective of the present study was to determine whether GD3S knockdown will protect neurons and prevent executive dysfunction following a subchronic regimen of 25-mg/kg 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). C57BL/6N wild-type mice were assessed on a battery of sensorimotor tasks and a reaction-time task that included measures of sustained attention and impulse control. Sustained attention was measured by response accuracy and reaction time; impulsivity was measured by premature responding in the response holes or the food well during the precue period. After reaching stable performance, mice received intrastriatal injections of a recombinant adeno-associated viral (AAV) vector expressing a short-hairpin RNA (shRNA) construct targeting St8sia1, the gene that codes for GD3S, or a scrambled-sequence control (scrRNA). After 4 weeks, mice received MPTP or saline injections. MPTP-lesioned mice in the scrRNA control group exhibited loss of impulse control in the sessions following MPTP injections, compared to the other three groups. These deficits abated with extended training but re-emerged on challenge sessions with shorter cue durations or longer precue durations. GD3S knockdown partially protected nigrostriatal neurons from MPTP neurotoxicity and prevented the motor impairments (coordination, bradykinesia, fine motor skills) and loss of impulse control. Our data suggest that inhibition of GD3S warrants further investigation as a novel therapeutic strategy for Parkinson's disease.

Exercise your graft - An important lesson for cell replacement therapy for Parkinson's disease

Parkinson's disease (PD) is a complex multisystem, chronic and so far, incurable disease affecting millions of people worldwide. With the continuing need for better therapeutic options for PD, there is a global renewed interest in cell replacement therapy due to progress in using pluripotent stem cells as an unlimited source of dopaminergic (DA) neurons for cell transplantation. Despite the significant progress made, obstacles remain that interfere with the restoration of functional circuits by DA grafts. The functional connectivity between DA grafts and host cells may be enhanced by adjunctive therapies, such as physical activity. Exercise modalities, such as use of treadmill, enhance neuroplasticity and improve motor and cognitive functions in PD patients. The patients are able to re-learn movement and adjust their posture, which, in turn, results in short term-reduced rigidity and improved stride length and cadence. By stabilizing selected active inputs and eliminating inactive ones, activity-dependent mechanisms fine-tune new neural circuits for optimal connection and physiological function. This communication will review the mechanisms and synergies between cell replacement therapy and physical and cognitive training to enhance induced pluripotent stem cell-mediated functional reinnervation of the striatum in PD.

Diabetes-related cognitive impairment: Mechanisms, symptoms, and treatments

Background

Diabetes-related cognitive impairment is increasingly recognized as a significant complication, profoundly impacting patients' quality of life. This review aims to examine the pathophysiological mechanisms, clinical manifestations, risk factors, assessment and diagnosis, management strategies, and future research directions of cognitive impairment in diabetes.

Methodology

A comprehensive literature search was conducted using PubMed, Medline, and other medical databases to identify, review, and evaluate published articles on cognitive impairment in diabetes. The search focused on studies examining pathophysiology, clinical presentations, risk factors, diagnostic approaches, and management strategies.

Results

The review of current literature revealed that chronic hyperglycemia, insulin resistance, and vascular factors are major contributing factors to cognitive deficits in diabetes. Clinical manifestations include impairments in attention, memory, executive function, visuospatial abilities, and language. Risk factors encompass disease duration, glycemic control, presence of complications, age, education level, and comorbidities. Assessment tools include cognitive screening instruments, neuropsychological testing, and neuroimaging techniques. Management strategies involve glycemic control optimization, lifestyle modifications, cognitive training, and pharmacological interventions.

Conclusion

This review highlights the significant prevalence and impact of cognitive impairment in diabetes, resulting from complex metabolic and vascular disturbances. Early detection and multifaceted interventions are crucial for preserving cognitive function and improving patient outcomes. Future research should focus on neuroprotective strategies, biomarker identification, and personalized approaches. Collaborative efforts between clinicians and researchers are essential to effectively address this growing healthcare challenge and enhance the quality of life for individuals with diabetes-related cognitive impairment.

The Neurometabolic Function of the Dopamine-Aminotransferase System

BACKGROUND/OBJECTIVES

The neurometabolic function is controlled by a complex multi-level physiological system that includes neurochemical, hormonal, immunological, sensory, and metabolic components. Functional disorders of monoamine systems are often detected in clinical practice together with metabolic dysfunctions. An important part of the mentioned pathological conditions are associated with disturbances in protein metabolism, some of the most important biomarkers which are aminotransferases and transcription factors that regulate and direct the most important metabolic reactions. Another important part of energy metabolism is the dopamine-mediated regulation of protein metabolism.

METHODS

The review describes research results into the dopamine-mediated mechanism of metabolic regulation in humans and animals. Particular attention is paid to the neurometabolic mechanisms of protein metabolism.

RESULTS

The dopamine-aminotransferase system of the energy metabolism regulation is a separate, independent, regulatory and diagnostically significant biochemical pathway controlled by the hormonal system, the key hormone is cortisol, the key neurotransmitter is dopamine, the key transcription factor is CREB, and the key regulatory enzymes are alanine aminotransferase, aspartate aminotransferase, and tyrosine aminotransferase.

CONCLUSIONS

This review presents an original study describing the discovery of a new regulatory mechanism for neurometabolic physiological function in humans and animals. A key part of this mechanism is the dopamine-aminotransferase system.

Do empirically-derived personality subtypes relate to cognitive inflexibility in anorexia nervosa and bulimia nervosa?

BACKGROUND

Accruing evidence suggests that personality-based approaches to eating disorder classification may offer several advantages over current diagnostic models, with prior research consistently identifying three personality-based groups characterized by either (1) high levels of impulsivity and dysregulation (termed the "undercontrolled" group), (2) high levels of rigidity and avoidance (termed the "overcontrolled" group), or (3) relatively normative levels of personality functioning (termed the "low psychopathology" group). Cognitive inflexibility (i.e., difficulty adjusting thoughts or behaviors) has theorized relevance to eating disorders. However, prior research has frequently failed to observe differences in cognitive inflexibility across eating disorder diagnostic groups. The present study aimed to identify personality-based groups in an eating disorder sample, and then to examine the relations between these groups and behavioral measures of cognitive inflexibility.

METHOD

83 men and women who met DSM-5 criteria for anorexia nervosa or bulimia nervosa completed self-report questionnaires to assess trait-level approach/avoidance behaviors and impulsivity, as well as behavioral tasks assessing attentional set-shifting and reversal learning, two facets of cognitive inflexibility.

RESULTS

Latent profile analysis of measures assessing approach/avoidance behaviors and impulsivity supported a three-class model replicating the undercontrolled, overcontrolled, and low psychopathology groups. Notably, the low psychopathology group was characterized by elevated reward responding. One-way ANOVAs indicated that the low psychopathology group demonstrated heightened perseverative errors (an indicator of impaired reversal learning) relative to the other groups. No group differences were observed for attentional set-shifting errors or probabilistic switch errors.

DISCUSSION

Findings from the present study provide additional support for personality-based classification approaches identifying undercontrolled, overcontrolled, and low psychopathology eating disorder groups. Results also suggest that reward-related processes may contribute to disorder maintenance in the low psychopathology group, indicating potentially meaningful targets for intervention.

Dopaminergic Treatment and Episodic Memory in Parkinson's Disease: A Meta-analysis of the Literature

To date, few studies have focused on the benefits of dopaminergic treatment on episodic memory functions in patients affected by Parkinson's disease (PD). We conducted a meta-analysis to determine the effects of pharmacological therapy with dopamine in alleviating episodic memory deficits in Parkinson's patients. A secondary aim was to evaluate the role of dopamine in episodic memory circuits and thus in different memory systems. We conducted a comprehensive literature search in PubMed (1971-2022) to find studies that met specific inclusion criteria. The studies had to provide sufficient data (means and standard deviations) to evaluate performance on neuropsychological tests of episodic memory. A total of k = 36 measures were included in the analysis. A statistically significant difference suggested better performance following dopaminergic therapy assumption (ON condition) than following dopaminergic withdrawal (OFF condition), specifically the estimated pooled effect calculated through a random-effects restricted maximum likelihood model was log ratio of means (RoM) = 0.047 (p = 0.011). The back-transformed RoM, indicating a 4.8% improvement, provides an interpretable measure of the effect size, as it reflects the multiplicative change in performance associated with the ON condition. A meta-regression analysis was also performed to assess the influence of specific memory tasks and relevant covariates/factors on the overall meta-analytic effect: four memory contrasts (verbal/visual, immediate/delayed, recall/recognition, word-list/short-story), age of participants, years of education, severity of illness, duration of illness in years, country of study, proportion of women in the sample, type of medication, counterbalancing. Word list/short story and proportion of women in the sample were the only two statistically significant predictors in the model, both associated with a positive higher pooled effect size. The present study revealed a significant overall difference between the results obtained in the ON and OFF conditions. We also found a significantly greater pharmacological effect in the recall of short stories than word lists, which supports the hypothesis of a beneficial effect of dopamine on the hippocampal circuit rather than on prefrontal cortical areas.

A hierarchical reinforcement learning model explains individual differences in attentional set shifting

Attentional set shifting refers to the ease with which the focus of attention is directed and switched. Cognitive tasks, such as the widely used CANTAB IED, reveal great variation in set shifting ability in the general population, with notable impairments in those with psychiatric diagnoses. The attentional and learning processes underlying this cognitive ability and how they lead to the observed variation remain unknown. To directly test this, we used a modelling approach on two independent large-scale online general-population samples performing CANTAB IED, with one including additional psychiatric symptom assessment. We found a hierarchical model that learnt both feature values and dimension attention best explained the data and that compulsive symptoms were associated with slower learning and higher attentional bias to the first relevant stimulus dimension. These data showcase a new methodology to analyse data from the CANTAB IED task, as well as suggest a possible mechanistic explanation for the variation in set shifting performance, and its relationship to compulsive symptoms.

Reward recalibrates rule representations in human amygdala and hippocampus intracranial recordings

Adaptive behavior requires the ability to shift responding within (intra-dimensional) or between (extra-dimensional) stimulus dimensions when reward contingencies change. Studies of shifting in humans have focused mainly on the prefrontal cortex and/ or have been restricted to indirect measures of neural activity such as fMRI and lesions. Here, we demonstrate the importance of the amygdala and hippocampus by recording local field potentials directly from these regions intracranially in human epilepsy patients. Reward signals were coded in the high frequency gamma activity (HFG; 60-250 Hz) of both regions and synchronised via low frequency (3-5 Hz) phase-locking only after a shift when patients did not already know the rule and it signalled to stop shifting ("Win-Stay"). In contrast, HFG punishment signals were only seen in the amygdala when the rule then changed and it signalled to start shifting ("Lose-Shift"). During decision-making, hippocampal HFG was more inhibited on non-shift relative to shift trials, suggesting a role in preventing interference in rule representation and amygdala HFG was sensitive to stimulus novelty. The findings expand our understanding of human amygdala-hippocampal function and shifting processes, the disruption of which could contribute to shifting deficits in neuropsychiatric disorders.

Graphophonological-semantic flexibility and its contribution to reading comprehension in children with dyslexia: A pilot study

Graphophonological-semantic flexibility is the cognitive flexibility in reading that enables individuals to manage multiple phonological and semantic aspects of text simultaneously. This study investigated graphophonological-semantic flexibility and its contribution to reading comprehension in children with dyslexia, comparing them to age-matched, typically developing peers. Thirty children aged 8-11 were assessed using a reading-specific sorting task, where they categorized word cards by initial phoneme and meaning within a 2x2 matrix. After sorting, participants explained their arrangements, and their sorting speed, accuracy, and composite scores were evaluated. Additionally, reading comprehension was assessed through passages followed by questions. Results revealed significant differences between children with dyslexia and their peers in sorting accuracy and composite scores. Children with dyslexia exhibited poorer accuracy and longer sorting times, leading to lower composite scores indicative of reduced graphophonological-semantic flexibility. Age showed a positive correlation with sorting accuracy and composite scores. Moreover, sorting accuracy and composite scores were strong predictors of reading comprehension. These findings suggest that children with dyslexia face challenges in managing both phonological and semantic aspects of text concurrently, highlighting the importance of graphophonological-semantic flexibility in reading development.

Opening new vistas on obsessive-compulsive disorder with the observing response task

Obsessive-compulsive disorder (OCD), a highly prevalent and debilitating disorder, is incompletely understood in terms of underpinning behavioural, psychological, and neural mechanisms. This is attributable to high symptomatic heterogeneity; cardinal features comprise obsessions and compulsions, including clinical subcategories. While obsessive and intrusive thoughts are arguably unique to humans, dysfunctional behaviours analogous to those seen in clinical OCD have been examined in nonhuman animals. Genetic, ethological, pharmacological, and neurobehavioural approaches all contribute to understanding the emergence and persistence of compulsive behaviour. One behaviour of particular interest is maladaptive checking, whereby human patients excessively perform checking rituals despite these serving no purpose. Dysfunctional and excessive checking is the most common symptom associated with OCD and can be readily operationalised in rodents. This review considers animal models of OCD, the neural circuitries associated with impairments in habit-based and goal-directed behaviour, and how these may link to the compulsions observed in OCD. We further review the Observing Response Task (ORT), an appetitive instrumental learning procedure that distinguishes between functional and dysfunctional checking, with translational application in humans and rodents. By shedding light on the psychological and neural bases of compulsive-like checking, the ORT has potential to offer translational insights into the underlying mechanisms of OCD, in addition to being a platform for testing psychological and neurochemical treatment approaches.

Combining physical & cognitive training with iPSC-derived dopaminergic neuron transplantation promotes graft integration & better functional outcome in parkinsonian marmosets

Parkinson's disease (PD) is a relentlessly progressive and currently incurable neurodegenerative disease with significant unmet medical needs. Since PD stems from the degeneration of midbrain dopaminergic (DA) neurons in a defined brain location, PD patients are considered optimal candidates for cell replacement therapy. Clinical trials for cell transplantation in PD are beginning to re-emerge worldwide with a new focus on induced pluripotent stem cells (iPSCs) as a source of DA neurons since they can be derived from adult somatic cells and produced in large quantities under current good manufacturing practices. However, for this therapeutic strategy to be realized as a viable clinical option, fundamental translational challenges need to be addressed including the manufacturing process, purity and efficacy of the cells, the method of delivery, the extent of host reinnervation and the impact of patient-centered adjunctive interventions. In this study we report on the impact of physical and cognitive training (PCT) on functional recovery in the nonhuman primate (NHP) model of PD after cell transplantation. We observed that at 6 months post-transplant, the PCT group returned to normal baseline in their daily activity measured by actigraphy, significantly improved in their sensorimotor and cognitive tasks, and showed enhanced synapse formation between grafted cells and host cells. We also describe a robust, simple, efficient, scalable, and cost-effective manufacturing process of engraftable DA neurons derived from iPSCs. This study suggests that integrating PCT with cell transplantation therapy could promote optimal graft functional integration and better outcome for patients with PD.

Idiopathic basal ganglia calcification presenting with obsessive-compulsive symptoms: A case report

Background

Idiopathic basal ganglia calcification (IBGC), also known as Farh's disease, is a rare neurodegenerative disorder characterized by calcification of the basal ganglia and other brain regions. This disease usually occurs in middle-aged patients and presents with various neurological and psychiatric symptoms. The exact prevalence is unknown; however, population genomic data analysis suggests a prevalence of at least 4.5/10,000 to 3.3/1000, indicating that the disease is more common than previously thought and remains underdiagnosed.

Case Presentation

We report the case of a middle-aged Japanese man who attempted suicide twice because of obsessive-compulsive ideation caused by trivial triggers. The patient's psychiatric symptoms resolved relatively quickly after hospitalization, and imaging and genetic testing led to a diagnosis of IBGC.

Conclusion

This case report illustrates the importance of including IBGC in the differential diagnosis of psychiatric symptoms that initially develop in middle-aged patients.

Psychosocial needs and outcomes of adults with spina bifida: A scoping review, 1974-2023

Limited evidence exists that serves to guide the field of practice and research pertaining to the long-term issues and needs of adults with spina bifida. Understanding the lived experience of adults with spina bifida has lagged behind considerably resulting in limited evidence-based guidance for individuals with spina bifida and their families and the health care professionals who provide services to this population. Given the paucity of knowledge of the lived experience as it pertains to adulthood, this scoping review was undertaken. More than 10,000 records from 1974 through 2023 were screened based upon the search criteria whose purpose was to examine the research conducted the psychosocial outcomes and needs of adults with spina bifida. A total of 81 articles were included in this review. The findings of this review revealed significant gaps were apparent. There was limited data on adulthood benchmarks of employment, education, community living and social relationships. Limitations associated with the investigations of this review included underpowered samples, lack of longitudinal designs, use of instruments with insufficient psychometrics, and the use of clinical and administrative data sets not designed for research purposes. As the survival rates of individuals with spina bifida continue to improve with medical advances more robust psychosocial research pertaining to this population is needed.

A meta-analysis of cognitive flexibility in autism spectrum disorder

Cognitive flexibility is a fundamental process that underlies adaptive behaviour in response to environmental change. Studies examining the profile of cognitive flexibility in autism spectrum disorder (ASD) have reported inconsistent findings. To address whether difficulties with cognitive flexibility are characteristic of autism, we conducted a random-effects meta-analysis and employed subgroup analyses and meta-regression to assess the impact of relevant moderator variables such as task, outcomes, and age. Fifty-nine studies were included and comprised of 2122 autistic individuals without intellectual disabilities and 2036 neurotypical controls, with an age range of 4 to 85 years. The results showed that autistic individuals have greater difficulties with cognitive flexibility, with an overall statistically significant small to moderate effect size. Subgroup analyses revealed a significant difference between task outcomes, with perseverative errors obtaining the largest effect size. In summary, the present meta-analysis highlights the existence of cognitive flexibility difficulties in autistic people, in the absence of learning disabilities, but also that this profile is characterised by substantial heterogeneity. Potential contributing factors are discussed.

Prospective associations between cognitive flexibility and eating disorder symptoms in anorexia nervosa and bulimia nervosa

This study investigated concurrent and prospective associations between measures of reversal learning and attentional set-shifting and eating disorder symptoms at baseline, 3 months, and 6 months among individuals with anorexia nervosa restricting subtype (AN-R, n = 26), AN binge eating/purging subtype (AN-BP, n = 22), bulimia nervosa (BN, n = 35), and healthy controls (n = 27), and explored whether these associations differed by diagnosis. At baseline, participants completed diagnostic interviews, height/weight measurements, and measures of set-shifting (the Intradimensional/Extradimensional shift task) and reversal learning (a probabilistic reversal learning task). At 3- and 6-month follow-up, participants with eating disorders completed assessments of weight and eating disorder symptoms. A one-way analysis of variance found no evidence that baseline reversal learning and attentional set-shifting differed across diagnostic groups. Multilevel modeling analyses indicated that perseverative errors (an index of reversal learning) predicted an increase in purging over time for individuals with AN-BP and BN. Set-shifting errors differentially predicted frequency of loss of control eating for individuals with AN-BP and BN; however, set-shifting was not related to loss of control eating when examined separately in AN-BP and BN. These findings suggest that disentangling facets of cognitive flexibility may help understand change in eating disorder symptoms.

Executive dysfunction and cognitive decline, a non-motor symptom of Parkinson's disease captured in animal models

The non-motor symptoms of Parkinson's disease (PD) have gained increasing attention in recent years due to their significant impact on patients' quality of life. Among these non-motor symptoms, cognitive dysfunction has emerged as an area of particular interest where the clinical aspects are covered in Chapter 2 of this volume. This chapter explores the rationale for investigating the underlying neurobiology of cognitive dysfunction by utilising translational animal models of PD, from rodents to non-human primates. The objective of this chapter is to review the various animal models of cognition that have explored the dysfunction in animal models of Parkinson's disease. Some of the more advanced pharmacological studies aimed at restoring these cognitive deficits are reviewed, although this chapter highlights the lack of systematic approaches in dealing with this non-motor symptom at the pre-clinical stages.

Basal ganglia ischaemic infarction after thrombectomy: cognitive impairment at acute stage

BACKGROUND AND PURPOSE

After successful mechanical thrombectomy for middle cerebral artery occlusion, basal ganglia infarction is commonly detectable. Whilst the functional outcome of these patients is often good, less knowledge is available about the cognitive outcome. The aim of our study was to assess the presence of cognitive impairment within 1 week after thrombectomy.

METHODS

In all, 43 subjects underwent a general cognitive assessment using the Montreal Cognitive Assessment and an extensive battery of tests. Patients were classified as cognitively impaired (CImp) or not (noCImp) according to a Montreal Cognitive Assessment score below 18.

RESULTS

Cognitively impaired and noCImp subjects did not differ either in their National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) at admittance, or in their Fazekas score and Alberta Stroke Program Early Computed Tomography Score. At discharge, CImp subjects showed higher scores than noCImp subjects on NIHSS (p = 0.002) and mRS (p < 0.001). The percentage of pathological performances on each neuropsychological test in the whole sample and in CImp and noCImp patients shows a similar cognitive profile between the groups.

CONCLUSIONS

Some patients who underwent thrombectomy experienced a detectable cognitive impairment that probably led to worse NIHSS and mRS. The neuropsychological profile of such cognitive impairment at the acute stage consists of wide deficits in numerous cognitive domains, suggesting that basal ganglia damage may lead to complex functional impairments.

Contributions of the Basal Ganglia to Visual Perceptual Decisions

The basal ganglia (BG) make up a prominent nexus between visual and motor-related brain regions. In contrast to the BG's well-established roles in movement control and value-based decision making, their contributions to the transformation of visual input into an action remain unclear, especially in the context of perceptual decisions based on uncertain visual evidence. This article reviews recent progress in our understanding of the BG's contributions to the formation, evaluation, and adjustment of such decisions. From theoretical and experimental perspectives, the review focuses on four key stations in the BG network, namely, the striatum, pallidum, subthalamic nucleus, and midbrain dopamine neurons, which can have different roles and together support the decision process.

The dopaminergic system supports flexible and rewarding dyadic motor interactive behaviour in Parkinson's Disease

Studies indicate that the dopaminergic system (DAS) supports individual flexible behaviour. While flexibility is quintessential to effective dyadic motor interactions, whether DAS mediates adaptations of one's own motor behaviour to that of a partner is not known. Here, we asked patients with Parkinson's Disease (PD) to synchronize their grasping movements with those of a virtual partner in conditions that did (Interactive) or did not (Cued) require to predict and adapt to its actions. PD performed the task during daily antiparkinsonian treatment ('On' condition) or after drug-withdrawal ('Off' condition). A group of healthy individuals also served as control group. In the Interactive condition, PDs performed better and found the interaction more enjoyable when in 'On' than in 'Off' condition. Crucially, PD performance in the 'On' condition did not differ from that of healthy controls. This pattern of results hints at the key role of the DAS in supporting the flexible adaptation of one's own actions to the partner's during motor interactions.

Perception of Physical Demand, Mental Demand, and Performance: A Comparison of Two Voice Interventions for Parkinson's Disease

PURPOSE

The purpose of the study was to examine the effect of two voice intervention approaches for hypophonia secondary to Parkinson's disease (PD) on self-reported measures of physical demand, mental demand, and vocal performance.

METHOD

Thirty-four persons with hypophonia secondary to PD were assigned to one of three groups: Lee Silverman Voice Treatment (LSVT) LOUD (n = 12), SpeechVive (n = 12), and nontreatment clinical control (n = 10). The LSVT LOUD and the SpeechVive participants received 8 weeks of voice intervention following the standardized protocol previously described for each approach. To confirm the effectiveness of each voice intervention, sound pressure level (dB SPL) data were analyzed for the experimental and control participants for a monologue sample obtained pretreatment, midtreatment, and posttreatment. During the voice intervention period, the LSVT LOUD and the SpeechVive participants were instructed to complete a modified version of the National Aeronautics and Space Administration Task Load Index rating scale to indicate the mental and physical demand required to complete the intervention activities, and to indicate how well they performed in completing the assigned vocal tasks.

RESULTS

The LSVT LOUD and the SpeechVive participants demonstrated a significant posttreatment increase in SPL (dB), in comparison to the clinical controls, thus confirming a positive intervention effect. The LSVT LOUD participants reported significantly higher ratings of physical and mental demand over the course of treatment, in comparison to the SpeechVive participants.

CONCLUSION

Consideration of the mental and physical demand associated with two voice intervention approaches, commonly used for PD, may help to foster improved therapeutic compliance and treatment outcomes.

The marmoset as a model for investigating the neural basis of social cognition in health and disease

Social-cognitive processes facilitate the use of environmental cues to understand others, and to be understood by others. Animal models provide vital insights into the neural underpinning of social behaviours. To understand social cognition at even deeper behavioural, cognitive, neural, and molecular levels, we need to develop more representative study models, which allow testing of novel hypotheses using human-relevant cognitive tasks. Due to their cooperative breeding system and relatively small size, common marmosets (Callithrix jacchus) offer a promising translational model for such endeavours. In addition to having social behavioural patterns and group dynamics analogous to those of humans, marmosets have cortical brain areas relevant for the mechanistic analysis of human social cognition, albeit in simplified form. Thus, they are likely suitable animal models for deciphering the physiological processes, connectivity and molecular mechanisms supporting advanced cognitive functions. Here, we review findings emerging from marmoset social and behavioural studies, which have already provided significant insights into executive, motivational, social, and emotional dysfunction associated with neurological and psychiatric disorders.

Disentangling Reversal-learning Impairments in Frontotemporal Dementia and Alzheimer Disease

BACKGROUND

Individuals with frontotemporal dementia (FTD) often present with poor decision-making, which can affect both their financial and social situations. Delineation of the specific cognitive impairments giving rise to impaired decision-making in individuals with FTD may inform treatment strategies, as different neurotransmitter systems have been associated with distinct patterns of altered decision-making.

OBJECTIVE

To use a reversal-learning paradigm to identify the specific cognitive components of reversal learning that are most impaired in individuals with FTD and those with Alzheimer disease (AD) in order to inform future approaches to treatment for symptoms related to poor decision-making and behavioral inflexibility.

METHOD

We gave 30 individuals with either the behavioral variant of FTD or AD and 18 healthy controls a stimulus-discrimination reversal-learning task to complete. We then compared performance in each phase between the groups.

RESULTS

The FTD group demonstrated impairments in initial stimulus-association learning, though to a lesser degree than the AD group. The FTD group also performed poorly in classic reversal learning, with the greatest impairments being observed in individuals with frontal-predominant atrophy during trials requiring inhibition of a previously advantageous response.

CONCLUSION

Taken together, these results and the reversal-learning paradigm used in this study may inform the development and screening of behavioral, neurostimulatory, or pharmacologic interventions aiming to address behavioral symptoms related to stimulus-reinforcement learning and response inhibition impairments in individuals with FTD.

Role of dopamine and clinical heterogeneity in cognitive dysfunction in Parkinson's disease

Parkinson's disease (PD) is commonly treated with dopaminergic medication, which enhances some, while impairing other cognitive functions. It can even contribute to impulse control disorder and addiction. We describe the history of research supporting the dopamine overdose hypothesis, which accounts for the large within-patient variability in dopaminergic medication effects across different tasks by referring to the spatially non-uniform pattern of dopamine depletion in dorsal versus ventral striatum. However, there is tremendous variability in dopaminergic medication effects not just within patients across distinct tasks, but also across different patients. In the second part of this chapter we review recent studies addressing the large individual variability in the negative side effects of dopaminergic medication on functions that implicate dopamine, such as value-based learning and choice. These studies begin to unravel the mechanisms of dopamine overdosing, thus revising the strict version of the overdose hypothesis. For example, the work shows that the canonical boosting of reward-versus punishment-based choice by medication is greater in patients with depression and a non-tremor phenotype, which both implicate, among other pathology, more rather than less severe dysregulation of the mesolimbic dopamine system. Future longitudinal cohort studies are needed to identify how to optimally combine different clinical, personality, cognitive, neural, genetic and molecular predictors of detrimental medication effects in order to account for as much of the relevant variability as possible. This will provide a useful tool for precision neurology, allowing individual and contextual tailoring of (the dose of) dopaminergic medication in order to maximize its cognitive benefits, yet minimize its side effects.

A New Remote Guided Method for Supervised Web-Based Cognitive Testing to Ensure High-Quality Data: Development and Usability Study

BACKGROUND

The global COVID-19 pandemic has triggered a fundamental reexamination of how human psychological research can be conducted safely and robustly in a new era of digital working and physical distancing. Online web-based testing has risen to the forefront as a promising solution for the rapid mass collection of cognitive data without requiring human contact. However, a long-standing debate exists over the data quality and validity of web-based studies. This study examines the opportunities and challenges afforded by the societal shift toward web-based testing and highlights an urgent need to establish a standard data quality assurance framework for online studies.

OBJECTIVE

This study aims to develop and validate a new supervised online testing methodology, remote guided testing (RGT).

METHODS

A total of 85 healthy young adults were tested on 10 cognitive tasks assessing executive functioning (flexibility, memory, and inhibition) and learning. Tasks were administered either face-to-face in the laboratory (n=41) or online using remote guided testing (n=44) and delivered using identical web-based platforms (Cambridge Neuropsychological Test Automated Battery, Inquisit, and i-ABC). Data quality was assessed using detailed trial-level measures (missed trials, outlying and excluded responses, and response times) and overall task performance measures.

RESULTS

The results indicated that, across all data quality and performance measures, RGT data was statistically-equivalent to in-person data collected in the lab (P>.40 for all comparisons). Moreover, RGT participants out-performed the lab group on measured verbal intelligence (P<.001), which could reflect test environment differences, including possible effects of mask-wearing on communication.

CONCLUSIONS

These data suggest that the RGT methodology could help ameliorate concerns regarding online data quality-particularly for studies involving high-risk or rare cohorts-and offer an alternative for collecting high-quality human cognitive data without requiring in-person physical attendance.

Cognitive Rigidity, Habitual Tendencies, and Obsessive-Compulsive Symptoms: Individual Differences and Compensatory Interactions

Recent theories have posited a range of cognitive risk factors for obsessive-compulsive disorder (OCD), including cognitive inflexibility and a maladaptive reliance on habits. However, empirical and methodological inconsistencies have obscured the understanding of whether inflexibility and habitual tendencies indeed shape OCD symptoms in clinical and sub-clinical populations, and whether there are notable interactions amongst these traits. The present investigation adopted an interactionist individual differences approach to examine the associations between behaviorally-assessed cognitive flexibility and subclinical OCD symptomatology in a healthy population. It also explored the nature of the interactions between cognitive flexibility and habitual tendencies, and the degree to which these cognitive traits predict subclinical OCD symptomatology. Across two studies, including a preregistration, Bayesian and regression analyses revealed that cognitive inflexibility and compulsive habitual tendencies act as unique and independent predictors of subclinical OCD symptomatology in healthy populations. Furthermore, there was a significant interaction between cognitive rigidity and habitual compulsivity, which accounted for 49.4% of the variance in subclinical OCD symptomatology in Study 1, and 37.3% in Study 2. In-depth analyses revealed a compensatory effect between cognitive inflexibility and habitual compulsivity such that both are necessary for OCD symptomatology, but neither is sufficient. These results imply that in order to generate reliable and nuanced models of the endophenotype of OCD symptomatology, it is essential to account for interactions between psychological traits. Moreover, the present findings have important implications for theories on the cognitive roots of OCD, and potentially in the development of interventions that target both cognitive inflexibility and habitual compulsivity.

Diabetes and Cognitive Impairment: A Role for Glucotoxicity and Dopaminergic Dysfunction

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by hyperglycemia, responsible for the onset of several long-term complications. Recent evidence suggests that cognitive dysfunction represents an emerging complication of DM, but the underlying molecular mechanisms are still obscure. Dopamine (DA), a neurotransmitter essentially known for its relevance in the regulation of behavior and movement, modulates cognitive function, too. Interestingly, alterations of the dopaminergic system have been observed in DM. This review aims to offer a comprehensive overview of the most relevant experimental results assessing DA’s role in cognitive function, highlighting the presence of dopaminergic dysfunction in DM and supporting a role for glucotoxicity in DM-associated dopaminergic dysfunction and cognitive impairment. Several studies confirm a role for DA in cognition both in animal models and in humans. Similarly, significant alterations of the dopaminergic system have been observed in animal models of experimental diabetes and in diabetic patients, too. Evidence is accumulating that advanced glycation end products (AGEs) and their precursor methylglyoxal (MGO) are associated with cognitive impairment and alterations of the dopaminergic system. Further research is needed to clarify the molecular mechanisms linking DM-associated dopaminergic dysfunction and cognitive impairment and to assess the deleterious impact of glucotoxicity.

Cortical Serotonergic and Catecholaminergic Denervation in MPTP-Treated Parkinsonian Monkeys

Decreased cortical serotonergic and catecholaminergic innervation of the frontal cortex has been reported at early stages of Parkinson's disease (PD). However, the limited availability of animal models that exhibit these pathological features has hampered our understanding of the functional significance of these changes during the course of the disease. In the present study, we assessed longitudinal changes in cortical serotonin and catecholamine innervation in motor-symptomatic and asymptomatic monkeys chronically treated with low doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Densitometry and unbiased stereological techniques were used to quantify changes in serotonin and tyrosine hydroxylase (TH) immunoreactivity in frontal cortices of 3 control monkeys and 3 groups of MPTP-treated monkeys (motor-asymptomatic [N = 2], mild parkinsonian [N = 3], and moderate parkinsonian [N = 3]). Our findings revealed a significant decrease (P < 0.001) in serotonin innervation of motor (Areas 4 and 6), dorsolateral prefrontal (Areas 9 and 46), and limbic (Areas 24 and 25) cortical areas in motor-asymptomatic MPTP-treated monkeys. Both groups of symptomatic MPTP-treated animals displayed further serotonin denervation in these cortical regions (P < 0.0001). A significant loss of serotonin-positive dorsal raphe neurons was found in the moderate parkinsonian group. On the other hand, the intensity of cortical TH immunostaining was not significantly affected in motor asymptomatic MPTP-treated monkeys, but underwent a significant reduction in the moderate symptomatic group (P < 0.05). Our results indicate that chronic intoxication with MPTP induces early pathology in the corticopetal serotonergic system, which may contribute to early non-motor symptoms in PD.

Neurophysiological responses of globus pallidus internus during the auditory oddball task in Parkinson's disease

Parkinson's disease can be associated with significant cognitive impairment that may lead to dementia. Deep brain stimulation (DBS) of the subthalamic nucleus is an effective therapy for motor symptoms but is associated with cognitive decline. DBS of globus pallidus internus (GPi) poses less risk of cognitive decline so may be the preferred target. A research priority is to identify biomarkers of cognitive decline in this population, but efforts are hampered by a lack of understanding of the role of the different basal ganglia nuclei, such as the globus pallidus, in cognitive processing. During deep brain stimulation (DBS) surgery, we monitored single units, beta oscillatory LFP activity as well as event related potentials (ERPs) from the globus pallidus internus (GPi) of 16 Parkinson's disease patients, while they performed an auditory attention task. We used an auditory oddball task, during which one standard tone is presented at regular intervals and a second deviant tone is presented with a low probability that the subject is requested to count and report at the end of the task. All forms of neuronal activity studied were selective modulated by the attended tones. Of 62 neurons studied, the majority (51 or 82%) responded selectively to the deviant tone. Beta oscillatory activity showed an overall desynchronization during both types of attended tones interspersed by bursts of beta activity giving rise to peaks at a latency of around 200 ms after tone onset. cognitive ERPs recorded in GPi were selective to the attended tone and the right-side cERP was larger than the left side. The averages of trials showing a difference in beta oscillatory activity between deviant and standard also had a significant difference in cERP amplitude. In one block of trials, the random occurrence of 3 deviant tones in short succession silenced the activity of the GPi neuron being recorded. Trial blocks where a clear difference in LFP beta was seen were twice as likely to yield a correct tone count (25 vs 11). The data demonstrate strong modulation of GPi neuronal activity during the auditory oddball task. Overall, this study demonstrates an involvement of GPi in processing of non-motor cognitive tasks such as working memory and attention, and suggests that direct effects of DBS in non-motor GPi may contribute to cognitive changes observed post-operatively.

Dissociable effects of age and Parkinson's disease on instruction-based learning

The cognitive deficits associated with Parkinson's disease vary across individuals and change across time, with implications for prognosis and treatment. Key outstanding challenges are to define the distinct behavioural characteristics of this disorder and develop diagnostic paradigms that can assess these sensitively in individuals. In a previous study, we measured different aspects of attentional control in Parkinson's disease using an established fMRI switching paradigm. We observed no deficits for the aspects of attention the task was designed to examine; instead those with Parkinson's disease learnt the operational requirements of the task more slowly. We hypothesized that a subset of people with early-to-mid stage Parkinson's might be impaired when encoding rules for performing new tasks. Here, we directly test this hypothesis and investigate whether deficits in instruction-based learning represent a characteristic of Parkinson's Disease. Seventeen participants with Parkinson's disease (8 male; mean age: 61.2 years), 18 older adults (8 male; mean age: 61.3 years) and 20 younger adults (10 males; mean age: 26.7 years) undertook a simple instruction-based learning paradigm in the MRI scanner. They sorted sequences of coloured shapes according to binary discrimination rules that were updated at two-minute intervals. Unlike common reinforcement learning tasks, the rules were unambiguous, being explicitly presented; consequently, there was no requirement to monitor feedback or estimate contingencies. Despite its simplicity, a third of the Parkinson's group, but only one older adult, showed marked increases in errors, 4 SD greater than the worst performing young adult. The pattern of errors was consistent, reflecting a tendency to misbind discrimination rules. The misbinding behaviour was coupled with reduced frontal, parietal and anterior caudate activity when rules were being encoded, but not when attention was initially oriented to the instruction slides or when discrimination trials were performed. Concomitantly, Magnetic Resonance Spectroscopy showed reduced gamma-Aminobutyric acid levels within the mid-dorsolateral prefrontal cortices of individuals who made misbinding errors. These results demonstrate, for the first time, that a subset of early-to-mid stage people with Parkinson's show substantial deficits when binding new task rules in working memory. Given the ubiquity of instruction-based learning, these deficits are likely to impede daily living. They will also confound clinical assessment of other cognitive processes. Future work should determine the value of instruction-based learning as a sensitive early marker of cognitive decline and as a measure of responsiveness to therapy in Parkinson's disease.

Prefrontal cortex VAMP1 gene network moderates the effect of the early environment on cognitive flexibility in children

During development, genetic and environmental factors interact to modify specific phenotypes. Both in humans and in animal models, early adversities influence cognitive flexibility, an important brain function related to behavioral adaptation to variations in the environment. Abnormalities in cognitive functions are related to changes in synaptic connectivity in the prefrontal cortex (PFC), and altered levels of synaptic proteins. We investigated if individual variations in the expression of a network of genes co-expressed with the synaptic protein VAMP1 in the prefrontal cortex moderate the effect of early environmental quality on the performance of children in cognitive flexibility tasks. Genes overexpressed in early childhood and co-expressed with the VAMP1 gene in the PFC were selected for study. SNPs from these genes (post-clumping) were compiled in an expression-based polygenic score (PFC-ePRS-VAMP1). We evaluated cognitive performance of the 4 years-old children in two cohorts using similar cognitive flexibility tasks. In the first cohort (MAVAN) we utilized two CANTAB tasks: (a) the Intra-/Extra-dimensional Set Shift (IED) task, and (b) the Spatial Working Memory (SWM) task. In the second cohort, GUSTO, we used the Dimensional Change Card Sort (DCCS) task. The results show that in 4 years-old children, the PFC-ePRS-VAMP1 network moderates responsiveness to the effects of early adversities on the performance in attentional flexibility tests. The same result was observed for a spatial working memory task. Compared to attentional flexibility, reversal learning showed opposite effects of the environment, as moderated by the ePRS. A parallel ICA analysis was performed to identify relationships between whole-brain voxel based gray matter density and SNPs that comprise the PFC-ePRS-VAMP1. The early environment predicts differences in gray matter content in regions such as prefrontal and temporal cortices, significantly associated with a genetic component related to Wnt signaling pathways. Our data suggest that a network of genes co-expressed with VAMP1 in the PFC moderates the influence of early environment on cognitive function in children.

Loss of control over eating: A systematic review of task based research into impulsive and compulsive processes in binge eating

Recurring episodes of excessive food intake in binge eating disorder can be understood through the lens of behavioral control systems: patients repeat maladaptive behaviors against their explicit intent. Self-report measures show enhanced impulsivity and compulsivity in binge eating (BE) but are agnostic as to the processes that might lead to impulsive and compulsive behavior in the moment. Task-based neurocognitive investigations can tap into those processes. In this systematic review, we synthesize neurocognitive research on behavioral impulsivity and compulsivity in BE in humans and animals, published between 2010-2020. Findings on impulsivity are heterogeneous. Findings on compulsivity are sparse but comparatively consistent, indicating an imbalance of goal-directed and habitual control as well as deficits in reversal learning. We urge researchers to address heterogeneity related to mood states and the temporal dynamics of symptoms, to systematically differentiate contributions of body weight and BE, and to ascertain the validity and reliability of tasks. Moreover, we propose to further scrutinize the compulsivity findings to unravel the computational mechanisms of a potential reinforcement learning deficit.

Differential Treatment Effects of Methylphenidate and Atomoxetine on Executive Functions in Children with Attention-Deficit/Hyperactivity Disorder

Objectives: This study aimed to compare the efficacy of methylphenidate and atomoxetine on improving executive functions among children with attention-deficit/hyperactivity disorder (ADHD). Methods: This was an open-label, head-to-head, 3-month, randomized clinical trial with two-arm parallel-treatment groups: osmotic-release oral system methylphenidate (OROS-MPH; n = 79) and atomoxetine once daily (n = 78). Three major domains of executive functions were assessed, including response selection/inhibition, flexibility, and planning/working memory. The neuropsychological measures included the Conners' continuous performance test and the Cambridge Neuropsychological Test Automated Battery. Results: We found that both treatment groups showed improvement in executive functions (p-value <0.05 for the major indices of each domain). In addition, OROS-MPH was associated with a greater magnitude of improvement in the response selection/inhibition; the slope for detectability improvement in the Conners' continuous performance test was 0.06 for atomoxetine and 0.15 for OROS-MPH (p-value <0.01); the slope in rapid visual information processing was 2.22 for atomoxetine and 3.45 for OROS-MPH (p-value <0.05). Conclusion: Both OROS-MPH and atomoxetine improved various domains of executive functions in children with ADHD. There is greater improvement in response selection/inhibition among patients treated with OROS-MPH than those with atomoxetine. This trial was registered with ClinicalTrials.gov (no. NCT00916786).

The Importance of Common Currency Tasks in Translational Psychiatry

Purpose of Review

Common currency tasks are tasks that investigate the same phenomenon in different species. In this review, we discuss how to ensure the translational validity of common currency tasks, summarise their benefits, present recent research in this area and offer future directions and recommendations.

Recent Findings

We discuss the strengths and limitations of three specific examples where common currency tasks have added to our understanding of psychiatric constructs—affective bias, reversal learning and goal-based decision making.

Summary

Overall, common currency tasks offer the potential to improve drug discovery in psychiatry. We recommend that researchers prioritise construct validity above face validity when designing common currency tasks and suggest that the evidence for construct validity is summarised in papers presenting research in this area.

What Can Performance in the IEDS Task Tell Us About Attention Shifting in Clinical Groups?

The Intra-Extra-dimensional set shift task (IEDS) is a widely used test of learning and attention, believed to be sensitive to aspects of executive function. The task proceeds through a number of stages, and it is generally claimed that patterns of errors across stages can be used to discriminate between reduced attention switching and more general reductions in rates of learning. A number of papers have used the IEDS task to argue for specific attention shifting difficulties in Autism Spectrum Disorder (ASD) and Schizophrenia, however, it remains unclear how well the IEDS really differentiates between reduced attention shifting and other causes of impaired performance. To address this issue, we introduce a simple computational model of performance in the IEDS task, designed to separate the competing effects of attention shifting and general learning rate. We fit the model to data from ASD and comparison individuals matched on age and IQ, as well as to data from four previous studies which used the IEDS task. Model fits do not show consistent evidence for reductions in attention shifting rates in ASD and Schizophrenia. Instead, we find performance is better explained by differences in learning rate, particularly from punishment, which we show correlates with IQ. We, therefore, argue that the IEDS task is not a good measure of attention shifting in clinical groups. LAY SUMMARY: The Intra-Extra-Dimensional Set shift task (IEDS) is often given to autistic individuals, who tend to make more errors relative to comparison groups. This higher error rate is taken to mean that autistic individuals struggle with attention control. Our computational model of the IEDS shows that the performance of ASD and some other clinical groups can be explained instead by differences in learning rate, rather than differences in attention control.

Cognitive Inflexibility in OCD and Related Disorders

Cognitive inflexibility is suggested by the hallmark symptoms of obsessive-compulsive disorder (OCD), namely the occurrence of repetitive thoughts and/or behaviours that persist despite being functionally impairing and egodystonic to the individual. As well as being implied by the top-level symptoms, cognitive inflexibility in OCD, and some related conditions, has also been objectively quantified in case-control studies using computerised cognitive tasks. This chapter begins by considering the objective measurement of different aspects of cognitive flexibility using neuropsychological paradigms, with a focus on neural and neurochemical substrates. It moves on to conduct a systematic review and meta-analysis of findings from a widely deployed flexibility task: the Intra-Dimensional/Extra-Dimensional Set-Shift Task (IDED). By pooling data from 11 studies (335 OCD patients and 311 controls), we show that Extra-Dimensional (ED) shift deficits are a robust and reproducible finding (effect size medium-large) in OCD across the literature, and that this deficit is not attributable to group differences in age or IQ. The OCD ED deficit is then discussed in terms of dysfunction of fronto-striatal pathways (as exemplified, for example, by functional connectivity data), and the putative role of different neurotransmitters. We consider evidence that impaired ED shifting constitutes a candidate vulnerability marker (or 'endophenotype') for OCD. The available literature is then surveyed as to ED findings in other obsessive-compulsive (OC) related disorders (e.g. hoarding, body-dysmorphic disorder, and trichotillomania), as well as in non-OC disorders (schizophrenia and anxiety symptoms in general). Lastly, we consider more recent, emerging developments in the quantification of compulsivity using cognitive tasks and questionnaires, as well as key directions for future research, including the need to refine compulsivity and its composite cognitive processes.

The role of cognitive functions in the diagnosis of bipolar disorder: A machine learning model

BACKGROUND

Considering the clinical heterogeneity of the bipolar disorder, difficulties are encountered in making the correct diagnosis. Although a number of common findings have been found in studies on the neurocognitive profile of bipolar disorder, the search for a neurocognitive endophenotype has failed. The aim of this study is to separate bipolar disorder patients from healthy controls with higher accuracy by using a broader neurocognitive evaluation and a novel machine-learning algorithm.

METHODS

Individuals who presented to the Bipolar Outpatient Clinic of the Medical Faculty of Eskişehir Osmangazi University and met the inclusion criteria of the research are included in the study. Six neurocognitive tests from the CANTAB test battery were used for neurocognitive evaluation, Polyhedral Conic Functions algorithm was used to classify the participants.

RESULTS

Bipolar disorder patients differentiated from healthy controls with an accuracy of 78 %.

DISCUSSION

Our study presents a prediction algorithm that separates bipolar disorder from healthy controls with high accuracy by using CANTAB neurocognitive battery.

Parent Psychopathology and Neurocognitive Functioning in Children With ADHD

Objective: The objective of this study was to examine the association between parent mental health (ADHD and depression) and offspring performance on neurocognitive tasks in children with ADHD. Method: The clinical sample consisted of 570 children (85% males, mean age: 10.77 years) with ADHD who completed neurocognitive tasks measuring working memory, attention set-shifting, and motivational deficits. Questionnaire measures were used to assess ADHD and depression symptom presence in parents. Results: Controlling for ADHD severity, children of parents with ADHD had poorer working memory (B = -0.25, 95% confidence interval [CI] [-0.45, -0.07], p = .01) and increased errors on the extra dimensional shift stage of the set-shifting task (B = 0.26 95% CI [0.02, 0.50], p = .04). Parent depression was not associated with offspring performance on any of the assessed neurocognitive tasks. Conclusion: Children with ADHD who have a parent with ADHD symptom presence are a subgroup of children who may have additional neurocognitive impairments that have potential implications when implementing interventions that target cognition and learning.

Impulsivity and compulsivity in anorexia and bulimia nervosa: A systematic review

This study aimed to systematically appraise cross-sectional research that compared the cognitive performance of individuals in the acute phase of BN and/or AN to HCs on measures of impulsivity and compulsivity. The results of the systematic review showed support for the trans-diagnostic approach to eating disorders. There was no strong evidence to support the characterisation of AN as high in compulsivity (and low in impulsivity), nor to support the characterisation of BN as high in impulsivity (and low in compulsivity). There appeared to be mixed findings for both impulsivity and compulsivity across AN and BN. Results were highly variable due to the heterogeneous tasks used, and lack of replication across studies. There was no consensus amongst the included studies on the most appropriate task and/or outcome measures that should be used to study the constructs of impulsivity and compulsivity.

A systematic review and meta-analysis of behavioural sex differences in executive control

Literature investigating whether an individuals' sex affects their executive control abilities and performance on cognitive tasks in a normative population has been contradictory and inconclusive. Using meta-analytic procedures (abiding by PRISMA guidelines), this study attempts to identify the magnitude of behavioural sex differences in three prominent executive control domains of cognitive set-shifting, performance monitoring, and response inhibition. PubMed, Web of Science, and Scopus were systematically searched. Across 46 included studies, a total of 1988 females and 1884 males were included in the analysis. Overall, males and females did not differ on performance in any of the three domains of performance monitoring, response inhibition, or cognitive set-shifting. Task-specific sex differences were observed in the domains of performance monitoring, in the CANTAB Spatial Working Memory task-males scored statistically higher than females (Hedges' g = -0.60), and response inhibition, in the Delay Discounting task-females scored statistically higher than males (Hedges' g = 0.64). While the meta-analysis did not detect overall behavioural sex differences in executive control, significant heterogeneity and task-specific sex differences were found. To further understand sex differences within these specific tasks and domains, future research must better control for age and sex hormone levels.

Impaired cognitive function in Crohn's disease: Relationship to disease activity

Background & aims

Impaired attention and response inhibition have been reported in patients with Crohn’s disease (CD) in clinical remission. Prospective studies are needed to determine whether this is a stable feature of CD and whether a similar impairment is evident in ulcerative colitis (UC). Thus, our aims were to examine whether patients with CD and UC exhibited a persistent impairment in attentional performance, and if this impairment was related to key biological indices of relevance to cognition.

Methods

A prospective observational study was conducted on fifteen patients with CD and 7 with UC in clinical remission recruited from a specialty clinic and 30 healthy matched control participants. A neuropsychological assessment was carried out at baseline (visit 1) and at a 6 month follow-up (visit 2). Plasma proinflammatory cytokines, the plasma kynurenine:tryptophan (Kyn:Trp) ratio and the salivary cortisol awakening response (CAR) were also determined at each visit.

Results

Across visits, patients with CD exhibited impaired attentional performance (p ​= 0.023). Plasma IL-6 (P ​= ​0.001) and the Kyn:Trp ratio (P ​= ​0.03) were consistently elevated and the CAR significantly blunted (P ​< ​0.05) in patients with CD. No significant relationships were identified between any biochemical parameter and altered cognitive performance.

Conclusions

Impaired cognitive function is a stable feature of patients with CD. These data suggest that even where remission has been achieved, the functional impact of an organic gastrointestinal disorder on cognition is still evident. However, it is unclear at present if physiological changes due to disease activity play a role in cognitive impairment in CD.

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Crohn’s disease (CD) patients previously associated with impaired cognition.

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CD patients consistently exhibited impaired attentional performance at multiple visits.

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Functional impact of organic gastrointestinal disorder on cognition still evident in remission.

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Increased IL-6, kynurenine pathway activation and blunted cortisol awakening response in CD.

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Biochemical parameters not associated with altered cognitive performance.

Are candidate neurocognitive endophenotypes of OCD present in paediatric patients? A systematic review

To-date it has been difficult to ascertain the exact cognitive profile of childhood OCD as studies report variable results. Adult OCD research lately utilises the endophenotype approach; studying cognitive traits that are present in both patients and their unaffected first-degree relatives, and are thought to lie closer to the genotype than the full-blown disorder. By observing whether candidate endopenotypes of adult OCD are present in child patients, we can determine whether the two subtypes show cognitive overlap. We conducted a systematic review of the paediatric OCD literature focussing on proposed neurocognitive endophenotypes of OCD: cognitive flexibility, response inhibition, memory, planning, decision-making, action monitoring, and reversal learning. We found that paediatric patients present robust increases in brain error related negativity associated with abnormal action monitoring, impaired decision-making under uncertainty, planning, and visual working memory, but there is less evidence for deficits in other cognitive domains. This implies that children with OCD show some cognitive similarities with adult patients, but other dysfunctions may only manifest later in the disorder trajectory.

Acute anxiety and autonomic arousal induced by CO2 inhalation impairs prefrontal executive functions in healthy humans

Acute anxiety impacts cognitive performance. Inhalation of air enriched with carbon dioxide (CO2) in healthy humans provides a novel experimental model of generalised anxiety, but has not previously been used to assess cognition. We used inhalation of 7.5% CO2 to induce acute anxiety and autonomic arousal in healthy volunteers during neuropsychological tasks of cognitive flexibility, emotional processing and spatial working memory in a single-blind, placebo-controlled, randomized, crossover, within-subjects study. In Experiment 1 (n = 44), participants made significantly more extra-dimensional shift errors on the Cambridge Neuropsychological Test Automated Battery (CANTAB) Intra-Extra Dimensional Set Shift task under CO2 inhalation compared with 'normal' air. Participants also had slower latencies when responding to positive words and made significantly more omission errors for negative words on the CANTAB Affective Go/No-go task. In Experiment 2 (n = 28), participants made significantly more total errors and had poorer heuristic search strategy on the CANTAB Spatial Working Memory task. In both experiments, CO2 inhalation significantly increased negative affect; state anxiety and fear; symptoms of panic; and systolic blood pressure/heart rate. Overall, CO2 inhalation produced robust anxiogenic effects and impaired fronto-executive functions of cognitive flexibility and working memory. Effects on emotional processing suggested a mood-congruent slowing in processing speed in the absence of a negative attentional bias. State-dependent effects of anxiety on cognitive-emotional interactions in the prefrontal cortex warrant further investigation.

Context-Dependent Behavior in Parkinson’s Disease With Freezing of Gait

Background. Context-dependent behavior is a phenomenon in which people demonstrate superior performance in the context where a motor task was originally learned, but show poorer performance in an unfamiliar context. Previous studies found that people with Parkinson’s disease (PD) demonstrated greater context-dependency than nondisabled adults. Moreover, the frontostriatal circuit appeared to play a role in mediating context-dependent behavior. Neuroimaging studies showed that people with PD and freezing of gait (FoG) had difficulty recruiting the frontostriatal circuit when performing a set-shifting task, known to be mediated by this neural network. Objective. This study aimed to investigate whether individuals with PD and FoG (PD + FoG) would be more context-dependent than those without FoG (PD − FoG). Furthermore, the association between context-dependent behavior and set-shifting ability would be determined. Methods. Sixteen individuals with PD + FoG, 15 participants with PD − FoG, and 15 nondisabled adults (Control) were recruited. The participants practiced 3 numerical sequences, each associated with a specific context. One day following practice, the participants were tested under 2 conditions: the sequence-context associations remained the same as practice or were changed. Set-shifting ability was measured by the Trail Making Test (TMT). Results. Compared to the PD − FoG group, the PD + FoG group showed a greater decrement in normalized motor performance when the sequence-context associations were changed. Context-dependency correlated with the TMT in the PD − FoG group but not in the PD + FoG or Control groups. Conclusion. While people with PD + FoG appeared to be more context-dependent than individuals without FoG, a relationship between context-dependent behavior and set-shifting existed only in those without FoG.

Intensity Resolution in Individuals With Parkinson's Disease: Sensory and Auditory Memory Limitations

Purpose The purpose of the current study was to examine sensory and auditory memory limitations on intensity resolution in individuals with Parkinson's disease as compared to healthy older and younger adults. Method Nineteen individuals with Parkinson's disease, 10 healthy age- and hearing-matched adults, and 10 healthy young adults were studied. The listeners participated in 2 intensity discrimination tasks: a lower memory load 4IAX task (sensory limitations) and a higher memory load ABX task (auditory memory limitations). Intensity resolution was examined across groups and tasks using a bias-free measurement of signal detectability known as d' (d-prime). Listeners also participated in a loudness scaling task where they were instructed to rate the loudness level of each signal intensity along the experimental continuum using a computerized 150-mm visual analog scale. Results Intensity discrimination sensitivity (d') was significantly poorer in the 4IAX and ABX conditions for the individuals with Parkinson's disease, as compared to the older and younger controls. Furthermore, a significant age-related difference was identified for the loudness scaling condition. The younger controls rated most stimuli along the experimental continuum significantly louder as compared to the older controls and the individuals with Parkinson's disease. Conclusions The present discrimination data suggest sensory and auditory memory limitations may contribute to the intensity resolution issues associated with Parkinson's disease. Age-related differences in loudness scaling will be reviewed.

Thirty-Five Years of Computerized Cognitive Assessment of Aging-Where Are We Now?

Over the past 35 years, the proliferation of technology and the advent of the internet have resulted in many reliable and easy to administer batteries for assessing cognitive function. These approaches have great potential for affecting how the health care system monitors and screens for cognitive changes in the aging population. Here, we review these new technologies with a specific emphasis on what they offer over and above traditional 'paper-and-pencil' approaches to assessing cognitive function. Key advantages include fully automated administration and scoring, the interpretation of individual scores within the context of thousands of normative data points, the inclusion of 'meaningful change' and 'validity' indices based on these large norms, more efficient testing, increased sensitivity, and the possibility of characterising cognition in samples drawn from the general population that may contain hundreds of thousands of test scores. The relationship between these new computerized platforms and existing (and commonly used) paper-and-pencil tests is explored, with a particular emphasis on why computerized tests are particularly advantageous for assessing the cognitive changes associated with aging.