Impaired cognitive flexibility and motor inhibition in unaffected first-degree relatives of patients with obsessive-compulsive disorder

Proactive control for conflict resolution is intact in subclinical obsessive-compulsive individuals

Background

Obsessive-compulsive (OC) traits (i.e., tendency to implement stereotyped behaviors to avoid negative consequences) are transversally observed in psychiatric disorders largely differing in terms of clinical manifestations and etiopathogenesis. Interestingly, OC traits were also extensively found in the prodromal phases of the full-blown psychopathology and in healthy relatives of affected individuals. Moreover, OC traits were found to be associated—and possibly underlain by—cognitive control impairments. Nonetheless, the role of such interplay in the onset of OC disorders is yet to be understood. We hypothesized that OC traits are associated with abnormalities in proactively implement cognitive control for solving conflict.

Methods

We administered healthy individuals (n = 104) with the perifoveal spatial Stroop task to measure their ability of solving conflict in a proactive fashion, and with Obsessive-Compulsive Inventory (OCI) to stratify population according to the severity of OC traits.

Results

Analysis of response times by means of Linear Mixed-effect models revealed that proactive control performance was not associated with and the severity of OC traits. Furthermore, an equivalence test (Two One-Sided Test) revealed that the association between OCI scores and task performance was equivalent to zero.

Conclusion

These results suggest that the interplay between OC traits and proactive control abnormalities might not contribute to the development of OC-related disorders. Therefore, the role of other cognitive endophenotypes should be scrutinized for exploiting alternative prevention and intervention strategies.

Consistency within change: Evaluating the psychometric properties of a widely used predictive-inference task

Rapid adaptation to sudden changes in the environment is a hallmark of flexible human behaviour. Many computational, neuroimaging, and even clinical investigations studying this cognitive process have relied on a behavioural paradigm known as the predictive-inference task. However, the psychometric quality of this task has never been examined, leaving unanswered whether it is indeed suited to capture behavioural variation on a within- and between-subject level. Using a large-scale test-retest design (T1: N = 330; T2: N = 219), we assessed the internal (internal consistency) and temporal (test-retest reliability) stability of the task's most used measures. We show that the main measures capturing flexible belief and behavioural adaptation yield good internal consistency and overall satisfying test-retest reliability. However, some more complex markers of flexible behaviour show lower psychometric quality. Our findings have implications for the large corpus of previous studies using this task and provide clear guidance as to which measures should and should not be used in future studies.

Neuropsychological Functioning Among Patients with OCD in Asian Countries: A Systematic Review

Objective

This systematic review aimed to identify the effect of obsessive compulsive disorder (OCD) on cognitive processes, such as memory, executive functioning, and cognitive flexibility, among the adult populations of Asian countries.

Methods

The systematic review progressed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. It is comprised of articles sourced from Asian countries published from 2018 to 2022, and literature about deficits in memory, executive functioning, and cognitive flexibility in the OCD population was gathered from five electronic databases, including Google Scholar, PubMed, Research Gate, Science Direct, and Wiley Online Library. Full-text impact factor articles in the English language were considered in this study.

Results

This study screened 44 articles; five were included based on the eligibility criteria for the present systematic review. Four articles found cognitive deficits in the domains of executive functioning, memory, and cognitive flexibility among patients with OCD, whereas results of one article showed normal cognitive performance of the patients. Demographic variables showed no significant differences between patients with OCD and healthy controls.

Conclusion

This systematic review indicated deficits specifically in the cognitive functioning and flexibility of patients with OCD. Despite a noticeable prevalence of OCD in Asian countries, the literature on correlates and neurological functioning is scarce. Further studies are required to examine the effects on the larger population and provide knowledge in those countries and areas where people are suffering because of minimal knowledge regarding OCD.

Cognitive Training in Obsessive-Compulsive Disorder: A Systematic Review

Background

Cognitive training (CT) for illness-linked neuropsychological deficits has been attempted in psychiatric disorders and, more recently, in obsessive-compulsive disorder (OCD). However, studies are few and far between, with a limited understanding of factors contributing to efficacy. This article aims to provide a comprehensive critical review of studies employing CT in OCD.

Methods

This systematic review follows the Preferred Reporting of Items for Systematic Review and Meta-Analyses Protocols. Empirical studies that used any form of CT/remediation in individuals with OCD were included.

Results

Eight articles met the criteria for inclusion, of which five were randomized controlled trials, two were case series, and one was an open-label trial. The studies have predominantly demonstrated improved trained cognitive functions, with only two showing generalization to untrained domains like clinical symptoms and socio-occupational functioning.

Conclusion

There are few controlled trials of CT in OCD, which limits conclusions of efficacy. Given the sparse research in the area, the review summarizes the current status of research and examines important methodological considerations that may inform future studies.

Computational mechanism underlying switching of motor actions

Surviving in a constantly changing environment requires not only the ability to select actions, but also the flexibility to stop and switch actions when necessary. Extensive research has been devoted to understanding how the brain switches actions, yet the computations underlying switching and how it relates to selecting and stopping processes remain elusive. A central question is whether switching is an extension of the stopping process or involves different mechanisms. To address this question, we modeled action regulation tasks with a neurocomputational theory and evaluated its predictions on individuals performing reaches in a dynamic environment. Our findings suggest that, unlike stopping, switching does not necessitate a proactive pause mechanism to delay movement onset. However, switching engages a pause mechanism after movement onset, if the new target location is unknown prior to switch signal. These findings offer a new understanding of the action-switching computations, opening new avenues for future neurophysiological investigations.

Identification of biomarkers that predict response to subthalamic nucleus deep brain stimulation in resistant obsessive-compulsive disorder: protocol for an open-label follow-up study

INTRODUCTION

Deep brain stimulation (DBS) of bilateral anteromedial subthalamic nucleus (amSTN) has been found to be helpful in a subset of patients with severe, chronic and treatment-refractory obsessive-compulsive disorder (OCD). Biomarkers may aid in patient selection and optimisation of this invasive treatment. In this trial, we intend to evaluate neurocognitive function related to STN and related biosignatures as potential biomarkers for STN DBS in OCD.

METHODS AND ANALYSIS

Twenty-four subjects with treatment-refractory OCD will undergo open-label STN DBS. Structural/functional imaging, electrophysiological recording and neurocognitive assessment would be performed at baseline. The subjects would undergo a structured clinical assessment for 12 months postsurgery. A group of 24 healthy volunteers and 24 subjects with treatment-refractory OCD who receive treatment as usual would be recruited for comparison of biomarkers and treatment response, respectively. Baseline biomarkers would be evaluated as predictors of clinical response. Neuroadaptive changes would be studied through a reassessment of neurocognitive functioning, imaging and electrophysiological activity post DBS.

ETHICS AND DISSEMINATION

The protocol has been approved by the National Institute of Mental Health and Neurosciences Ethics Committee. The study findings will be disseminated through peer-reviewed scientific journals and scientific meetings.

The Psychopharmacology of Obsessive-Compulsive Disorder: A Preclinical Roadmap

This review evaluates current knowledge about obsessive-compulsive disorder (OCD), with the goal of providing a roadmap for future directions in research on the psychopharmacology of the disorder. It first addresses issues in the description and diagnosis of OCD, including the structure, measurement, and appropriate description of the disorder and issues of differential diagnosis. Current pharmacotherapies for OCD are then reviewed, including monotherapy with serotonin reuptake inhibitors and augmentation with antipsychotic medication and with psychologic treatment. Neuromodulatory therapies for OCD are also described, including psychosurgery, deep brain stimulation, and noninvasive brain stimulation. Psychotherapies for OCD are then reviewed, focusing on behavior therapy, including exposure and response prevention and cognitive therapy, and the efficacy of these interventions is discussed, touching on issues such as the timing of sessions, the adjunctive role of pharmacotherapy, and the underlying mechanisms. Next, current research on the neurobiology of OCD is examined, including work probing the role of various neurotransmitters and other endogenous processes and etiology as clues to the neurobiological fault that may underlie OCD. A new perspective on preclinical research is advanced, using the Research Domain Criteria to propose an adaptationist viewpoint that regards OCD as the dysfunction of a normal motivational system. A systems-design approach introduces the security motivation system (SMS) theory of OCD as a framework for research. Finally, a new perspective on psychopharmacological research for OCD is advanced, exploring three approaches: boosting infrastructure facilities of the brain, facilitating psychotherapeutic relearning, and targeting specific pathways of the SMS network to fix deficient SMS shut-down processes. SIGNIFICANCE STATEMENT: A significant proportion of patients with obsessive-compulsive disorder (OCD) do not achieve remission with current treatments, indicating the need for innovations in psychopharmacology for the disorder. OCD may be conceptualized as the dysfunction of a normal, special motivation system that evolved to manage the prospect of potential danger. This perspective, together with a wide-ranging review of the literature, suggests novel directions for psychopharmacological research, including boosting support systems of the brain, facilitating relearning that occurs in psychotherapy, and targeting specific pathways in the brain that provide deficient stopping processes in OCD.

Distinct Response Inhibition Patterns in Obsessive Compulsive Disorder Patients and Pathological Gamblers

Background: Obsessive-compulsive disorder (OCD) and pathological gambling (PG) are common disorders. The cognitive models of OCD and PG focus on abnormalities in response inhibition. Although, these functions have been studied in different PG and OCD samples, no study has compared the response inhibition in both. Methods: Medication-naïve OCD (n = 61) and PG subjects (n = 109) and healthy controls (n = 131) performed CPT and Go/NoGo tasks. Results: Compared to healthy controls (HC), PG and OCD groups underperformed on speed and exhibited larger time variability on the CPT and Go/NoGo task. Only in OCD patients, a positive correlation between omission errors and response time (RT) was observed in the CPT. At the Go/NoGo task, a negative correlation between false alarms and RT (a fast-errors trade-off) was significant only in the PG group. The HC group had greater sensitivity values (d') than the OCD and PG groups in the Go/NoGo task. The PG group displayed lower d' values and more conservative response criterion in the CPT. In addition, only the OCD group expressed a high switching cost compared to both the PG and HC groups in terms of the RT and d' values. Conclusions: Both the PG and OCD groups demonstrated impaired response inhibition compared to the HC group. On several measures, the OCD and PG groups showed comparable impairments, and in others these were distinct. Thus, it appears that distinct neurocognitive patterns are involved in performance of the CPT and the Go/NoGo tasks among OCD and PG subjects whose cognitive status is currently under intensive investigation.

Volitional saccade performance in a large sample of patients with obsessive-compulsive disorder and unaffected first-degree relatives

Recent evidence indicates that patients with obsessive-compulsive disorder (OCD) as well as their unaffected first-degree relatives show deficits in the volitional control of saccades, suggesting that volitional saccade performance may constitute an endophenotype of OCD. Here, we aimed to replicate and extend these findings in a large, independent sample. One hundred and fifteen patients with OCD, 103 healthy comparison subjects without a family history of OCD, and 31 unaffected first-degree relatives of OCD patients were examined using structured clinical interviews and performed a volitional saccade task as well as a prosaccade task. In contrast to previous reports, neither patients nor relatives showed impairments in the performance of volitional saccades compared to healthy controls. Notably, medicated patients did not differ from nonmedicated patients, and there was no effect of depressive comorbidity. Additional analyses investigating correlations between saccade performance and OCD symptom dimensions yielded no significant associations. In conclusion, the present results do not support the notion that volitional saccade execution constitutes an endophenotype of OCD. Possible explanations for inconsistencies with previous studies are discussed.

Biological markers for anxiety disorders, OCD and PTSD: A consensus statement. Part II: Neurochemistry, neurophysiology and neurocognition

OBJECTIVE

Biomarkers are defined as anatomical, biochemical or physiological traits that are specific to certain disorders or syndromes. The objective of this paper is to summarise the current knowledge of biomarkers for anxiety disorders, obsessive-compulsive disorder (OCD) and posttraumatic stress disorder (PTSD).

METHODS

Findings in biomarker research were reviewed by a task force of international experts in the field, consisting of members of the World Federation of Societies for Biological Psychiatry Task Force on Biological Markers and of the European College of Neuropsychopharmacology Anxiety Disorders Research Network.

RESULTS

The present article (Part II) summarises findings on potential biomarkers in neurochemistry (neurotransmitters such as serotonin, norepinephrine, dopamine or GABA, neuropeptides such as cholecystokinin, neurokinins, atrial natriuretic peptide, or oxytocin, the HPA axis, neurotrophic factors such as NGF and BDNF, immunology and CO2 hypersensitivity), neurophysiology (EEG, heart rate variability) and neurocognition. The accompanying paper (Part I) focuses on neuroimaging and genetics.

CONCLUSIONS

Although at present, none of the putative biomarkers is sufficient and specific as a diagnostic tool, an abundance of high quality research has accumulated that should improve our understanding of the neurobiological causes of anxiety disorders, OCD and PTSD.

Attention and Executive Function in Children Diagnosed with Attention Deficit Hyperactivity Disorder and Comorbid Disorders

OBJECTIVE

The goal of this study was to examine the relationship between comorbid disorders and executive function (EF) in children diagnosed with Attention Deficit/Hyperactivity Disorder (ADHD).

METHODS

Three hundred and fifty-five, 6-12 year old children clinically diagnosed with ADHD were included in the study. Comorbid anxiety disorders, Oppositional Defiant Disorder (ODD) and Conduct Disorder (CD) were examined. The EF domains were assessed using the Conners' Continuous Performance Test (CPT), Wisconsin Card Sorting Test (WCST), Tower of London (ToL), Finger Windows (FW) and Self Ordered Pointing Test (SOPT).

RESULTS

The findings indicate that children with comorbid anxiety disorders performed worse in domains measured by CPT and prior to controlling for age and sex, by FW. However, once sex was controlled for the results for FW were no longer significant. Children with CD obtained lower scores on WCST. Furthermore, a significant sex by CD interaction was observed.

CONCLUSION

These results indicate that comorbid disorders should be carefully examined as they play a significant role in EF performance and subsequently in day-to-day functioning of children with ADHD.

Association between neural reactivity and startle reactivity to uncertain threat in two independent samples

Prior studies indicate that anxiety disorders are associated with heightened sensitivity to uncertain threat (U threat). Individual differences in reactivity to U threat have been measured in the laboratory with two methodologies-startle eyeblink potentiation and fMRI. While startle and fMRI are purported to relate to each other, very little research exists on whether individual differences in one measure are associated with individual differences in another and, thus, whether startle and fMRI capture shared mechanisms. Therefore, the current study was designed to investigate if and where in the brain measures of startle potentiation and fMRI BOLD signal correlate during response to U threat across two independent samples. Participants in both studies completed two threat anticipation tasks-once during collection of startle potentiation and once during fMRI. In Study 1 (n = 43), the startle and fMRI tasks both used electric shock as the threat. As an extension, in Study 2 (n = 38), the startle task used electric shock but the fMRI task used aversive images. Despite these methodological differences, greater startle potentiation to U threat was associated with greater dorsal anterior cingulate, caudate, and orbitofrontal cortex reactivity to U threat in both samples. The findings suggest that startle and fMRI measures of responding to U threat overlap, and points toward an integrated brain-behavior profile of aberrant U threat responding.

Response Inhibition in Tic Disorders: Waiting to Respond Is Harder When ADHD Is Present

OBJECTIVE

Tic disorders such as Gilles-de-la-Tourette syndrome (TS) are associated with difficulties in withholding movements and sometimes inappropriate actions. The present study examined whether these disorders lead to a specific difficulty in withholding preprogrammed voluntary movements irrespective of decisions on whether or not to move.

METHOD

Children with TS with or without attention-deficit hyperactivity disorder (ADHD) and controls performed a fast-paced simple reaction time task involving responses to a target in a rapid letter stream (9 letters/s, average foreperiod 332 ms) with feedback on response speed.

RESULTS

The ADHD group showed more premature responses and more variable response time than other groups, whether the timing of the target was predictable or not.

CONCLUSION

The data indicate that in tic disorders, the presence of ADHD is associated with difficulties in waiting to initiate preprogrammed movements independently of response selection or response timing difficulties.

Cognitive Flexibility and Social Responsiveness in Children and Adolescents with Tourette Syndrome

This study examined cognitive flexibility and social responsiveness in children and adolescents with Tourette Syndrome (TS). Thirty one subjects with TS were compared to 32 age-matched healthy controls. Assessments included semi-structured interviews to assess psychopathology, parent-rated Social Responsiveness Scale (SRS) and a brief neuropsychological battery selected as measures of cognitive flexibility. Completion time for both Trail Making Tests (TMT-A and TMT-B) were significantly longer for TS group than controls, however the difference in perseverative errors on Wisconsin Card Sorting Test (WCST) was not significant. SRS total score was significantly higher in the TS group compared to controls, indicating greater impairment in social responsiveness. Group difference for TMTs and SRS failed to reach significance after controlling for co-occurring conditions. Clinicians might consider social impairment in the evaluation plan of children and adolescents with Tourette syndrome.

Response inhibition and interference control in patients with bipolar I disorder and first-degree relatives

OBJECTIVES

The current study aimed to assess both response inhibition (RI) and interference control (IC) in euthymic patients with bipolar disorder (BD-Ps) as well as asymptomatic first-degree relatives (BD-Rs) and healthy controls (HCs) in order to evaluate trait-as opposed to illness-associated features of these components.

METHODS

BD-Ps (n = 35) who had been in the euthymic state for at least six months, BD-Rs (n = 30), and HCs (n = 33) completed a Stop-Signal Task (SST) and Stroop Task to assess RI and IC, respectively. Groups were compared on the stop-signal reaction time (SSRT), stop-signal delay (SSD), mean reaction time on go trials (go-RT), Stroop interference score (S-interference), and number of errors on the color-word-naming trial (S-error). Associations between the patient's clinical features and RI and IC, between the patient's treatment and RI and IC, and between RI and IC in each group were investigated.

RESULTS

BD-Ps and BD-Rs had significantly shorter go-RT and SSD, and longer SSRT compared to HCs, with these scores being similar between the BD-Ps and BD-Rs. Also, both BD-Ps and BD-Rs made significantly more S-errors than HCs, whereas, the S-interference score was not significantly different between groups. There were no significant correlations between Stroop Task and SST scores within each group, nor between clinical features or treatment variables and RI and IC in BD-Ps.

CONCLUSIONS

Overall, impairment in RI and IC (only on S-error score) was present in both patients and relatives. The persistence of these deficits in the absence of mood symptoms suggests that these features may represent candidate endophenotypes for bipolar disorder.

DISSECTING OCD CIRCUITS: FROM ANIMAL MODELS TO TARGETED TREATMENTS

Obsessive-compulsive disorder (OCD) is a chronic, severe mental illness with up to 2-3% prevalence worldwide. In fact, OCD has been classified as one of the world's 10 leading causes of illness-related disability according to the World Health Organization, largely because of the chronic nature of disabling symptoms.([1]) Despite the severity and high prevalence of this chronic and disabling disorder, there is still relatively limited understanding of its pathophysiology. However, this is now rapidly changing due to development of powerful technologies that can be used to dissect the neural circuits underlying pathologic behaviors. In this article, we describe recent technical advances that have allowed neuroscientists to start identifying the circuits underlying complex repetitive behaviors using animal model systems. In addition, we review current surgical and stimulation-based treatments for OCD that target circuit dysfunction. Finally, we discuss how findings from animal models may be applied in the clinical arena to help inform and refine targeted brain stimulation-based treatment approaches.

Are there reliable changes in memory and executive functions after cognitive behavioural therapy in patients with obsessive-compulsive disorder?

INTRODUCTION

Patients with obsessive-compulsive disorder (OCD) have impaired memory and executive functions, but it is unclear whether these functions improve after cognitive behavioural therapy (CBT) of OCD symptoms. The primary aim of this study was to investigate whether memory and executive functions change after CBT in patients with OCD.

METHODS

We assessed 39 patients with OCD before and after CBT with neuropsychological tests of memory and executive functions. To correct for practice effects, 39 healthy controls (HCs) were assessed at two parallel time intervals with the neuropsychological tests.

RESULTS

There were no changes in memory and executive functions after CBT in patients with OCD when results were corrected for practice effects. Patients performed worse on a test of visuospatial memory and organisational skills (Rey complex figure test [RCFT]) compared to HCs both before and after CBT (ps = .002-.036).

CONCLUSIONS

The finding of persistent poor RCFT performances indicates that patients with OCD have impaired visuospatial memory and organisational skills that may be trait-related rather than state-dependent. These impairments may need to be considered in treatment. Our findings underline the importance of correcting for practice effects when investigating changes in cognitive functions.

Disrupted cortical network as a vulnerability marker for obsessive-compulsive disorder

Morphological alterations of brain structure are generally assumed to be involved in the pathophysiology of obsessive–compulsive disorder (OCD). Yet, little is known about the morphological connectivity properties of structural brain networks in OCD or about the heritability of those morphological connectivity properties. To better understand these properties, we conducted a study that defined three different groups: OCD group with 30 subjects, siblings group with 19 subjects, and matched controls group with 30 subjects. A structural brain network was constructed using 68 cortical regions of each subject within their respective group (i.e., one brain network for each group). Both small-worldness and modularity were measured to reflect the morphological connectivity properties of each constructed structural brain network. When compared to the matched controls, the structural brain networks of patients with OCD indeed exhibited atypical small-worldness and modularity. Specifically, small-worldness showed decreased local efficiency, and modularity showed reduced intra-connectivity in Module III (default mode network) and increased interconnectivity between Module I (executive function) and Module II (cognitive control/spatial). Intriguingly, the structured brain networks of the unaffected siblings showed similar small-worldness and modularity as OCD patients. Based on the atypical structural brain networks observed in OCD patients and their unaffected siblings, abnormal small-worldness and modularity may indicate a candidate endophenotype for OCD.

Dissociation of decision making under ambiguity and decision making under risk: a neurocognitive endophenotype candidate for obsessive-compulsive disorder

Evidence in the literature suggests that executive dysfunction is regarded as an endophenotype candidate for obsessive-compulsive disorder (OCD). Decision making is an important domain of executive function. However, few studies that have investigated whether decision making is a potential endophenotype for OCD have produced inconsistent results. Differences in the findings across these studies may be attributed to several factors: different study materials, comorbidity, medication, etc. There are at least two types of decision making that differ mainly in the degree of uncertainty and how much useful information about consequences and their probabilities are provided to the decision maker: decision making under ambiguity and decision making under risk. The aim of the present study was to simultaneously examine decision making under ambiguity as assessed by the Iowa Gambling Task (IGT) and decision making under risk as measured by the Game of Dice Task (GDT) in OCD patients and their unaffected first-degree relative (UFDR) for the first time. The study analyzed 55 medication-naïve, non-depressed OCD patient probands, 55 UFDRs of the OCD patients and 55 healthy matched comparison subjects (CS) without a family history of OCD with the IGT, the GDT and a neuropsychological test battery. While the OCD patients and the UFDRs performed worse than the CS on the IGT, they were unimpaired on the GDT. Our study supports the claim that decision making under ambiguity differs from decision making under risk and suggests that dissociation of decision making under ambiguity and decision making under risk may qualify to be a neurocognitive endophenotypes for OCD.

Compensatory frontoparietal activity during working memory: an endophenotype of obsessive-compulsive disorder

BACKGROUND

Subtle deficits in executive functioning are present in patients with obsessive-compulsive disorder (OCD) and their first-degree relatives, suggesting involvement of the frontoparietal circuits. The neural correlates of working memory may be a neurocognitive endophenotype of OCD.

METHODS

Forty-three unmedicated OCD patients, 17 unaffected siblings, and 37 matched comparison subjects performed a visuospatial n-back task, with a baseline condition (N0) and three working memory load levels (N1, N2, N3) during functional magnetic resonance imaging. Task-related brain activity was compared between groups in frontoparietal regions of interest. Generalized psychophysiological interaction analyses were used to study task-related changes in functional connectivity.

RESULTS

Obsessive-compulsive disorder patients, compared with comparison subjects and siblings, showed increased error rates at N3. Compared with comparison subjects, OCD patients showed task-related hyperactivation in left dorsal frontal areas and left precuneus associated with better task performance. Siblings exhibited hyperactivation in a bilateral frontoparietal network. Increased task load was associated with increased task-related brain activity, but in OCD patients and siblings this increase was smaller from load N2 to N3 than in comparison subjects. Obsessive-compulsive disorder patients, compared with siblings and comparison subjects, showed increased task-related functional connectivity between frontal regions and bilateral amygdala.

CONCLUSIONS

These findings indicate that compensatory frontoparietal brain activity in OCD patients and their unaffected relatives preserves task performance at low task loads but is insufficient to maintain performance at high task loads. Frontoparietal dysfunction may constitute a neurocognitive endophenotype for OCD, possibly reflecting limbic interference with and neural inefficiency within the frontoparietal network.

Response inhibition and interference control in obsessive-compulsive spectrum disorders

Over the past 20 years, motor response inhibition and interference control have received considerable scientific effort and attention, due to their important role in behavior and the development of neuropsychiatric disorders. Results of neuroimaging studies indicate that motor response inhibition and interference control are dependent on cortical–striatal–thalamic–cortical (CSTC) circuits. Structural and functional abnormalities within the CSTC circuits have been reported for many neuropsychiatric disorders, including obsessive–compulsive disorder (OCD) and related disorders, such as attention-deficit hyperactivity disorder, Tourette’s syndrome, and trichotillomania. These disorders also share impairments in motor response inhibition and interference control, which may underlie some of their behavioral and cognitive symptoms. Results of task-related neuroimaging studies on inhibitory functions in these disorders show that impaired task performance is related to altered recruitment of the CSTC circuits. Previous research has shown that inhibitory performance is dependent upon dopamine, noradrenaline, and serotonin signaling, neurotransmitters that have been implicated in the pathophysiology of these disorders. In this narrative review, we discuss the common and disorder-specific pathophysiological mechanisms of inhibition-related dysfunction in OCD and related disorders.

Cognitive deficits of executive functions and decision-making in obsessive-compulsive disorder

The nature of cognitive deficits in obsessive-compulsive disorder (OCD) is characterized by contradictory findings in terms of specific neuropsychological deficits. Selective impairments have been suggested to involve visuospatial memory, set shifting, decision-making and response inhibition. The aim of this study was to investigate cognitive deficits in decision-making and executive functioning in OCD. It was hypothesized that the OCD patients would be less accurate in their responses compared to the healthy controls in rational decision-making on a version of the Cambridge gambling task (CGT) and on the color-word interference test and on a version of the Tower of Hanoi test (tower test) of executive functioning. Thirteen participants with OCD were compared to a group of healthy controls (n = 13) matched for age, gender, education and verbal IQ. Results revealed significant differences between the OCD group and the healthy control group on quality of decision-making on the CGT and for achievement score on the tower test. On these two tasks the OCD group performed worse than the healthy control group. The symptom-dimension analysis revealed performance differences where safety checking patients were impaired on the tower test compared to contamination patients. Results are discussed in the framework of cognition and emotion processing and findings implicate that OCD models should address, specifically, the interaction between cognition and emotion. Here the emotional disruption hypothesis is forwarded to account for the dysfunctional behaviors in OCD. Further implications regarding methodological and inhibitory factors affecting cognitive information processing are highlighted.

Cognitive performance in a subclinical obsessive-compulsive sample 1: cognitive functions

Individuals who are not clinically diagnosed with obsessive-compulsive disorder (OCD) but still display obsessive-compulsive (OC) tendencies may show cognitive impairments. The present study investigated whether there are subgroups within a healthy group showing characteristic cognitive and emotional performance levels similar to those found in OCD patients and whether they differ from OCD subgroups regarding performance levels. Of interest are those cases showing subclinical symptomatology. The results revealed no impairments in the subclinical OC participants on the neuropsychological tasks, while evidence suggests that there exist high and low scores on two standardised clinical instruments (Yale-Brown Obsessive Compulsive Scale and Cognitive Assessment Instrument of Obsessions and Compulsions) in a healthy sample. OC symptoms may diminish the quality of life and prolong sustainable return to work. It may be that occupational rehabilitation programmes are more effective in rectifying subclinical OC tendencies compared to the often complex symptoms of diagnosed OCD patients. The relationship between cognitive style and subclinical OC symptoms is discussed in terms of how materials and information might be processed. Although subclinical OC tendencies would not seem to constitute a diagnosis of OCD, the quality of treatment programmes such as cognitive behavioural therapy can be improved based on the current investigation.

Neuropsychological functioning in obsessive-compulsive disorder: are executive functions the key deficit?

OBJECTIVE

Although several studies have examined neuropsychological functions in obsessive-compulsive disorder (OCD), findings are not conclusive, predominantly due to small samples and assessment of limited domains. We aim to map the neuropsychological profile of OCD in a large sample with a comprehensive battery of tests.

METHOD

Neuropsychological functions were tested in 150 subjects with DSM-IV OCD and 205 healthy control subjects.

RESULTS

Subjects with OCD performed significantly worse than healthy control subjects on Colour Trails 1 time, Tower of Hanoi 3-disk time, Wisconsin Card Sorting Test categories completed, Iowa Gambling Task, Complex Figure Test immediate and delayed recall (p<0.001).

CONCLUSIONS

Subjects with OCD evince deficits in scanning, planning time, concept formation, decision making and encoding of non-verbal memory after controlling for the effects of age, gender and education. The profile is suggestive of a predominantly executive dysfunction, with difficulties in strategizing and organizing stimuli and cognitive resources for maximum efficiency. The findings implicate dorsolateral prefrontal, superior medial prefrontal and anterior cingulate cortices, suggesting that OCD might not be a purely orbitofronto-striatal disorder as previously conceptualized.

Effects of chronic fluoxetine treatment on serotonin 1B receptor-induced deficits in delayed alternation

RATIONALE

Obsessive-compulsive disorder (OCD) patients show overactivation of the orbitofrontal cortex and deficits in cognitive tasks that require proper orbitofrontal functioning including delayed alternation tests of spatial working memory. We recently showed that OCD-like behavior is induced in mice by activating orbitofrontal serotonin 1B receptors (5-HT1Bs). However, the role of 5-HT1Bs in delayed alternation remains unclear.

OBJECTIVES

We examined the effects of 5-HT1B receptor activation on delayed alternation task (DAT) performance. We also assessed the ability of an effective OCD treatment, fluoxetine, to prevent 5-HT1B-induced deficits in DAT performance.

METHODS

Mice were tested on the DAT after acute treatment with saline, 3 or 6 mg/kg RU24969 (5-HT1B/1A agonist), 0.3 or 3 mg/kg 8-OH-DPAT (5-HT1A agonist), or co-injection with 3 mg/kg RU24969 and 5 mg/kg GR127935 (5-HT1B/1D antagonist). Separate mice were pretreated chronically (28 days) with 10 mg/kg fluoxetine and then tested on the DAT after acute treatment with 3 mg/kg RU24969, 0.3 mg/kg 8-OH-DPAT, or saline.

RESULTS

Both doses of RU24969 decreased accuracy and increased latency on the DAT, and GR127935 blocked RU24969-induced effects on accuracy. The 0.3 mg/kg 8-OH-DPAT did not affect the DAT performance, whereas 3 mg/kg increased omissions on the DAT. Finally, RU24969-induced DAT deficits were absent in fluoxetine-pretreated mice.

CONCLUSIONS

We show that 5-HT1B receptor activation disrupts DAT performance in mice, and chronic fluoxetine pretreatment blocks these 5-HT1B-induced deficits. Our findings suggest that 5-HT1B receptors play an important role in modulating orbitofrontal-dependent delayed alternation. Moreover, 5-HT1B-induced DAT deficits may provide a mouse model for DAT deficits in OCD.

Impaired volitional saccade control: first evidence for a new candidate endophenotype in obsessive-compulsive disorder

Recent research suggests that patients with obsessive-compulsive disorder (OCD) have deficits in the volitional control of saccades. Specific evidence comes from increased latencies of saccadic eye movements when they were volitionally executed but not when they were visually guided. The present study sought to test whether this deviance represents a cognitive endophenotype. To this end, first-degree relatives of OCD patients as genetic risk carriers were compared with OCD patients and healthy controls without a family history of OCD. Furthermore, as volitional response generation comprises selection and initiation of the required response, the study also sought to specify the cognitive mechanisms underlying impaired volitional response generation. Twenty-two unaffected first-degree relatives of OCD patients, 22 unmedicated OCD patients, and 22 healthy comparison subjects performed two types of volitional saccade tasks measuring response selection or only response initiation, respectively. Visually guided saccades were used as a control condition. Our results showed that unaffected first-degree relatives and OCD patients were significantly slowed compared to healthy comparison subjects in volitional response selection. Patients and relatives did not differ from each other. There was no group difference in the visually guided control condition. Taken together, the study provides first evidence that dysfunctional volitional response selection is a candidate endophenotype for OCD.

Brain structural abnormalities in obsessive-compulsive disorder: converging evidence from white matter and grey matter

INTRODUCTION

Specific cortico-striato-thalamic circuits are hypothesised to underlie the aetiology of obsessive-compulsive disorder (OCD). However, findings from neuroimaging studies have been inconsistent. In the current study, we attempted to provide a complete overview of structural alterations in OCD by conducting signed differential mapping (SDM) meta-analysis on grey matter and white matter studies of patients with OCD based on voxel-based morphometry (VBM) studies and diffusion tensor imaging (DTI) studies.

METHODS

Fifteen VBM and seven DTI case-control studies were included in this meta-analysis. SDM meta-analyses were performed to assess grey matter volume and white matter integrity changes in OCD patients and healthy controls.

RESULTS

We found that OCD patients had smaller grey matter volume than health controls in the frontal eye fields, medial frontal gyrus and anterior cingulate cortex. However, we showed that there was an increase in the grey matter volume in the lenticular nucleus, caudate nucleus and a small region in the right superior parietal lobule. OCD patients also had a lower fractional anisotropy (FA) in the cingulum bundles, inferior fronto-occipital fasciculus, and superior longitudinal fasciculus, while increased FA in the left uncinate fasciculus.

CONCLUSIONS

The current findings confirm the structural abnormalities of cortico-striato-thalamic circuits in OCD.

[The role of inhibition in obsessional-compulsive disorders]

INTRODUCTION

The nature of neuropsychological mechanisms underlying the clinical picture of obsessions and compulsions has not been clearly determined. A number of studies has emphasized the role of cognitive deficits, but diversity of methodology and overlapping of clinical sub-groups have not established a specific cognitive functioning of these patients. The studies carried out on executive functions have, however, helped to identify the important role that both inhibition and cognitive flexibility play in obsessive-compulsive (OC) symptoms. Most of them have found that a deficit of inhibition and alteration of cognitive flexibility could explain inflexibility and repetitive thoughts and actions typical of all types of OC disorders. The aim of the paper is to present the published data supporting the hypothesis of a specific role played by a deficit of inhibition and cognitive inflexibility. In the first, theoretical part, we present the neuropsychological approach emphasizing inhibition and lack of flexibility as a promising explanation of the functioning of OC disorders. In the second part, we will present studies using various measurements of inhibition and the results of which, therefore, support this hypothesis.

ARGUMENTS AND DISCUSSION

On the theoretical level, it is the model of attention that was used in explaining the OCD hypothesis. In the model of attention control of action, described by Norman, Shallice and Burgess, three systems were emphasized: one that takes care of routine actions, and the second that takes over the first in situations where automatic activities must stop in order to establish an attention control and therefore inhibit automatic responses. When selection of everyday and automatic activities is not sufficient to accomplish a task, it is the third system, that of cognitive control, which takes over. This supervisory attentional system operates in non-routine and ambiguous activities. The cognitive control is charged with detecting potential or emitted cognitive errors and resolving ambiguous situations. Neurocognitive studies show that cingular anterior cortex and prefrontal lateral cortex are engaged in ambiguous and conflicting situations. These two regions are considered essential for inhibition of routine actions, adjustment to change and, more generally, for an efficient and flexible behaviour. Repetitive nature of verification rituals in OCD could be explained in terms of lack of relationship between two systems, leaving in action the one that regulates automatic activities. Therefore, the rituals are considered to be under particular influence of the system which, being in charge of automatic actions, has a deficit in disengagement. Another model of attention, described by Posner, gives a further explanation of OCD. Mental inhibition has the capacity to treat information, either by applying strategies to control it (i.e. trying not to remember an unpleasant event) or leaving it to automatic control (i.e. incapacity to experience an emotion in relation to a particular event). In this way, the effort to suppress an intrusive thought is considered as controlled and deliberate cognitive treatment of emotionally charged information. In OCD, in the context of heightened anxiety, the assumed negative valence of information would influence habitual suppression of thought during controlled treatment. As a result, controlled efforts to suppress obsessions in emotionally stressful situations, would lead to the production of repetitive thoughts, as controlled treatment of information has failed in this action. On a clinical and experimental level, these studies have led to a better understanding and conceptualization of OCD. In spite of some conflicting results, there are concordant data in favour of hypotheses of the role of sub-cortical and frontal regions and their function in inhibition/desinhibition implied in the onset and maintenance of OCD. Functional neuroimagery anomalies are also in favour of the role of sub-cortical-frontal region in clinical manifestations of OCD. They are often associated with low performance in cognitive tasks, especially those implying frontal functions, which are, in turn, dependent on a necessary level of attention in order to guide or inhibit motor and cognitive programs.

Antisaccade performance in patients with obsessive-compulsive disorder and unaffected relatives: further evidence for impaired response inhibition as a candidate endophenotype

Cognitive dysfunctions such as inhibitory deficits and visuospatial abnormalities are often found in patients with obsessive-compulsive disorder (OCD). Recent findings in unaffected relatives indicate that response inhibition and other neuropsychological functions may also constitute endophenotypes of OCD. In the present study, 30 OCD patients, 30 first-degree relatives, and 30 healthy control subjects were assessed using a comprehensive neuropsychological test battery. A subsample of 21 subjects of each group also performed an antisaccade task. The samples were matched according to age, gender, education, and verbal intelligence. The OCD patients and the unaffected OCD relatives showed increased antisaccade error rates compared with the healthy control group (p = 0.003, p = 0.028, respectively). Significantly prolonged antisaccade latencies as compared to prosaccade latencies were only found in the OCD patients compared with the healthy control group (p = 0.019). Only OCD patients but not the unaffected OCD relatives were impaired with regard to visuospatial functions, problem-solving, and processing speed. Antisaccade errors did not correlate with severity of OCD or depressive symptoms. This study confirms inhibitory deficits, as indicated by increased antisaccade error rates, as a candidate endophenotype of OCD. In agreement with previous findings from imaging studies, our data suggest that functional abnormalities in frontostriatal and parietal cortical regions form part of the vulnerability for OCD.

Compulsive features in behavioural addictions: the case of pathological gambling

AIMS

To describe, in the context of DSM-V, how a focus on addiction and compulsion is emerging in the consideration of pathological gambling (PG).

METHODS

A systematic literature review of evidence for the proposed re-classification of PG as an addiction.

RESULTS

Findings include: (i) phenomenological models of addiction highlighting a motivational shift from impulsivity to compulsivity associated with a protracted withdrawal syndrome and blurring of the ego-syntonic/ego-dystonic dichotomy; (ii) common neurotransmitter (dopamine, serotonin) contributions to PG and substance use disorders (SUDs); (iii) neuroimaging support for shared neurocircuitries between 'behavioural' and substance addictions and differences between obsessive-compulsive disorder (OCD), impulse control disorders (ICDs) and SUDs; (iv) genetic findings more closely related to endophenotypic constructs such as compulsivity and impulsivity than to psychiatric disorders; (v) psychological measures such as harm avoidance identifying a closer association between SUDs and PG than with OCD; (vi) community and pharmacotherapeutic trials data supporting a closer association between SUDs and PG than with OCD. Adapted behavioural therapies, such as exposure therapy, appear applicable to OCD, PG or SUDs, suggesting some commonalities across disorders.

CONCLUSIONS

PG shares more similarities with SUDs than with OCD. Similar to the investigation of impulsivity, studies of compulsivity hold promising insights concerning the course, differential diagnosis and treatment of PG, SUDs, and OCD.

Neurobehavioral assessment in forensic practice

There is a growing awareness among mental health practitioners that many mental disorders previously believed to be primarily behavioral in nature, reflecting character and environment, are actually grounded in brain mal-development or brain disorder. This growing awareness, influenced by the advent of new diagnostic procedures and measures, is also found among forensic practitioners. In this paper, we describe some of the elements involved in conducting a neurobehavioral assessment of cognitive functioning, particularly in capital cases, organizing this material in terms of the professional disciplines - social work, mitigation investigation, psychological, and medical - with which these methods are mainly identified. The paper concludes with a brief discussion of how to integrate the multiple areas of expertise to create an accurate understanding of the neurobehavioral functioning and capacity of the subject. This is the basis from which civil and criminal forensic opinions must emanate.

Deficient inhibition of return in subclinical OCD only when attention is directed to the threatening aspects of a stimulus

BACKGROUND

Inhibition of return (IOR) is thought to reflect inhibition of previously attended but irrelevant stimuli. Deficient IOR would increase the likelihood of revisiting previously searched locations or objects, thus leading to unproductive perseverations.

METHOD

Therefore, using a novel IOR task, we investigated whether high scoring checkers attentional biases to threat would result in dysfunctional inhibitory functioning compared to low checkers. In two tasks, we compared 53 subclinical high and 49 low checkers regarding IOR effects for stimuli that were concordant with the concerns of high but not of low checkers (electrical kitchen appliances: e.g., toaster, kettle). The difference between the two tasks was the cueing procedure. In one task, an appliance was switched "ON" and "OFF" as an unpredictive cue, drawing attention to the functionality of the stimulus.

RESULTS

In this task, IOR was specifically attenuated in high checkers. In the other task, however, the cue was more abstract in form of a yellow outline that appeared around one of two appliances. Although the appliance was either "ON" or "OFF," this did not seem to matter and high checkers revealed a typical IOR pattern similar to low checkers.

CONCLUSIONS

We conclude that IOR mechanisms might not be generally deficient in high checkers; rather only when attention is drawn to the threatening aspects of ecologically valid stimuli, then disengagement of attention is deficient in high checkers. We make suggestions on how our task-specific findings may inform cognitive interventions that target attentional control in the treatment of checking/obsessive-compulsive disorder.

White matter abnormalities in children and adolescents with obsessive-compulsive disorder: a diffusion tensor imaging study

BACKGROUND

There is paucity of data on white matter (WM) abnormalities in juvenile obsessive-compulsive disorder (OCD). This study aimed to identify WM microstructure changes in juvenile OCD.

METHODS

Fifteen children and adolescents with OCD and 15 matched healthy controls underwent diffusion tensor imaging using a 3 Tesla (Achieva, Best, The Netherlands) magnetic resonance imaging scanner. Voxelwise analyses were conducted on data processed through tract-based spatial statistics (TBSS).

RESULTS

Patients significantly differed from controls in axial as well as radial diffusivities, but not in fractional anisotropy. Patients demonstrated significantly increased axial diffusivity in corpus callosum (genu, body, and splenium), right and left superior longitudinal fasciculi, left inferior longitudinal fasciculus, right and left cingulum, bilateral anterior thalamic radiations, bilateral anterior limb of internal capsule, left posterior limb of the internal capsule, and middle cerebellar peduncle. In addition, significantly increased radial diffusivity was seen in patients in genu of the corpus, right and left superior longitudinal fasciculi, left inferior longitudinal fasciculus, right and left uncinate fasciculi, bilateral anterior thalamic radiation, bilateral inferior fronto-occipital fasciculus, left posterior limb of internal capsule, right superior cerebellar peduncle, middle cerebellar peduncle, and right inferior cerebellar peduncle.

CONCLUSIONS

Our findings suggest involvement of multiple WM tracts in juvenile OCD. In addition to the widely proposed hypothesis of orbitofrontal-striato-thalamo-cortical circuitry deficits in the development of OCD, our findings suggest involvement of additional brain regions, possibly parietal cortex, lateral prefrontal cortex, and limbic system. The widespread differences in WM among cases and controls also points to the possibility of underlying myelination changes.

Neuropsychological study of patients with obsessive-compulsive disorder and their parents in China: searching for potential endophenotypes

OBJECTIVE

The existence of neuropsychological deficits has been implicated in obsessive-compulsive disorder (OCD), particularly memory, attention, and executive functions. However, few studies have focused on neuropsychological deficits in the relatives of OCD patients. The aim of this study was to investigate cognitive deficits in OCD patients and their parents.

METHODS

Forty patients with OCD, 48 parents of these patients, and 87 healthy controls completed a neuropsychological testing battery.

RESULTS

Both OCD patients and their parents showed impairments in delayed verbal memory and delayed visual memory. Furthermore, they performed worse than healthy controls in problem-solving ability.

CONCLUSION

Our study demonstrated familial aggregation of delayed memory deficits and impaired problem-solving ability, which may be the potential neuropsychological endophenotypes of hereditary susceptibility to OCD.

Neuropsychological correlates of insight in obsessive-compulsive disorder

OBJECTIVE

There are limited data on neuropsychological correlates of poor insight in obsessive-compulsive disorder (OCD). We hypothesize that poor insight may be associated with greater impairment in tasks of conflict resolution/response inhibition and possibly impairment in a task of verbal learning and memory.

METHOD

Insight and neuropsychological functions were assessed in 150 subjects with DSM-IV OCD. The neuropsychological data of 177 healthy control subjects were used for comparison.

RESULTS

Insight score correlated significantly with the Stroop Interference Test for conflict resolution/response inhibition (P = 0.002), and showed trends for significance with the Controlled Oral Word Association (COWA) average for verbal fluency (P = 0.021) and delayed recall on the Auditory Verbal Learning Test (AVLT) for verbal memory (P = 0.015). On regression analysis, the AVLT delayed recall, the COWA average, the Matrix score, the Yale-Brown Obsessive-Compulsive Scale total score, and current antipsychotic use emerged as significant predictors of poorer insight.

CONCLUSION

Poor insight is associated with greater impairments in conflict resolution/response inhibition, verbal memory, and fluency. Individuals with poorer insight may have difficulty in appropriately processing conflicting information, updating their memory with corrective information, and then accessing this corrective information to modify their irrational beliefs.

Neuroimaging of cognitive brain function in paediatric obsessive compulsive disorder: a review of literature and preliminary meta-analysis

Obsessive compulsive disorder (OCD) is a frequent psychiatric disorder with a prevalence of 1-3 %, and it places an enormous burden on patients and their relatives. Up to 50 % of all cases suffer from onset in childhood or adolescence, and the disorder often takes a chronic course with a poor long-term prognosis. Paediatric OCD, with its high familiality, is often referred to as a distinct OCD subtype that coincides with a developmental period in which the prefrontal cortex exhibits extensive structural and functional maturation. In the present review, we included all studies examining cognitive brain activation in children and/or adolescents with OCD. We conducted extensive literature searches for relevant articles (Pubmed, ScienceDirect) and summarize, tabulate, and discuss their results. For the eight activation studies using functional magnetic resonance imaging, we also performed preliminary meta-analyses to assess the most consistent hypo- and hyperactivation in paediatric OCD patients during cognitive task performance. The review of literature as well as our preliminary meta-analyses of paediatric studies indicated altered functional activation in the same brain regions of affective and cognitive cortico-striatal-thalamic (CST) circuits as for adult OCD patients despite some variations in the direction of activation difference. The still small number of studies that examined brain activation in paediatric OCD patients thereby largely converged with previous findings in adult patients and with the established neurobiological models of CST circuit dysfunction in OCD.

Motor inhibition and cognitive flexibility in eating disorder subtypes

Anorexia Nervosa (AN) and Bulimia Nervosa (BN) are complex Eating Disorders (EDs). Even if are considered two different diagnostic categories, they share clinical relevant characteristics. The evaluation of neurocognitive functions, using standardized neuropsychological assessment, could be a interesting approach to better understand differences and similarities between diagnostic categories and clinical subtypes in EDs thus improving our knowledge of the pathophisiology of EDs spectrum. This study explored cognitive flexibility and motor inhibition in patients with AN considering both Restricter and Binge/Purge subtypes, patients with BN and healthy comparisons subjects (HC). Intra-Extra Dimentional Set shifting Test and Stop Signal Task, selected from CANTAB battery, were administered to analyzed set-shifting and motor inhibition respectively. AN patients showed a deficient motor inhibition compared to HC, while no evidence for impaired motor inhibition was found in BN patients; a significant relationship between commission errors in the Stop Signal Task and attentional impulsiveness was found. Moreover, no difference in set-shifting abilities was found comparing all clinician groups and HC. So our results indicated no cognitive impairment in these two cognitive functions in BN patients, while AN and BN showed different performances in motor inhibition. A similar cognitive profile was found in other obsessive compulsive spectrum disorders. Finally, the paper suggests a new interactive approach for the study of cognitive profile in psychiatric disorders; it might be more useful since it is more closely related to the executive functions complexity.

Animal models of neuropsychiatry revisited: a personal tribute to Teitelbaum

Several themes and principles of behavioural neuroscience are evident in the work of Phillip Teitelbaum. He has emphasised the importance of studying behaviour in simple preparations, of re-synthesising complex behavioural patterns from these elemental 'building-blocks' and understanding their often hierarchical organisation. He also more recently has become interested in the possible power of behavioural endophenotypes. His work has resulted in a new emphasis on animal neuropsychology which is highly relevant to human psychopathology. This article illustrates these themes from examples taken from animal models of sensory neglect, drug addiction and cognitive syndromes associated with schizophrenia and other neuropsychiatric disorders.

Olfactory identification and discrimination in obsessive-compulsive disorder

BACKGROUND

Neuroimaging and neuropsychological data from patients with an obsessive-compulsive disorder (OCD) indicate the dysfunction of the orbitofrontal cortex (OFC). Olfactory processing has been associated with OFC function, although results from OCD studies regarding this sensory modality have been inconclusive. No previous study has analyzed both odor discrimination and identification capacity in OCD patients using "Sniffin' Sticks" tests. The aim of our study was to assess odor threshold, identification, discrimination, and nonverbal memory in OCD patients, in order to determine whether these functions were affected.

METHODS

Olfactory function was measured in 29 OCD patients and 29 healthy volunteers (HV) using the "Sniffin' Sticks" test and their nonverbal memory was scored with the Rey-Osterrieth Complex Figure Test.

RESULTS

OCD patients showed significant impairment in their odor performance and in their execution of the nonverbal memory task compared to HV. No statistical associations were found between the deficits in the two areas. The severity of depressive and obsessive-compulsive symptoms did correlate with olfactory identification.

CONCLUSION

Our findings support the hypothesis that olfactory and memory dysfunctions in OCD reflect different neurobiological alterations of the disorder, and point to the modulation effect of depressive and obsessive-compulsive symptoms on odor performance.

Translational approaches to obsessive-compulsive disorder: from animal models to clinical treatment

Obsessive-compulsive disorder (OCD) is characterized by obsessions (intrusive thoughts) and compulsions (repetitive ritualistic behaviours) leading to functional impairment. Accumulating evidence links these conditions with underlying dysregulation of fronto-striatal circuitry and monoamine systems. These abnormalities represent key targets for existing and novel treatment interventions. However, the brain bases of these conditions and treatment mechanisms are still not fully elucidated. Animal models simulating the behavioural and clinical manifestations of the disorder show great potential for augmenting our understanding of the pathophysiology and treatment of OCD. This paper provides an overview of what is known about OCD from several perspectives. We begin by describing the clinical features of OCD and the criteria used to assess the validity of animal models of symptomatology; namely, face validity (phenomenological similarity between inducing conditions and specific symptoms of the human phenomenon), predictive validity (similarity in response to treatment) and construct validity (similarity in underlying physiological or psychological mechanisms). We then survey animal models of OC spectrum conditions within this framework, focusing on (i) ethological models; (ii) genetic and pharmacological models; and (iii) neurobehavioural models. We also discuss their advantages and shortcomings in relation to their capacity to identify potentially efficacious new compounds. It is of interest that there has been rather little evidence of 'false alarms' for therapeutic drug effects in OCD models which actually fail in the clinic. While it is more difficult to model obsessive cognition than compulsive behaviour in experimental animals, it is feasible to infer cognitive inflexibility in certain animal paradigms. Finally, key future neurobiological and treatment research areas are highlighted.

Study of neurocognitive endophenotypes in drug-naïve obsessive-compulsive disorder patients, their first-degree relatives and healthy controls

OBJECTIVE

Obsessive-compulsive disorder (OCD) is a debilitating heritable neuropsychiatric condition. Attempts to delineate genetic contributions in OCD have met with limited success, with an ongoing search for neurocognitive endophenotypes. In this study, an attempt has been made to study and compare the neurocognitive functioning of patients with OCD, their first-degree relatives (FDRs) and healthy controls.

METHOD

A cross-sectional design study was carried out with thirty dyads of patients with OCD, their FDRs and thirty matched healthy controls and screened using Mini International Neuropsychiatric Interview, Verbal Adult Intelligence Scale, Yale Brown Obsessive-Compulsive Scale, Montgomery Åsberg Depression Rating Scale, International Personality Disorder Examination (Anankastic personality scale).Tests of National Institute of Mental Health and Neurosciences Neuropsychological Battery were used to assess domains of attention, verbal memory, visual memory, set-shifting, response inhibition, planning and visuoconstructive abilities. spss version 14.0 was used for descriptive and analytical data analysis.

RESULTS

There were no statistically significant differences between patients with OCD and their FDRs on neurocognitive domains of delayed verbal recall, set-shifting, response inhibition and visuoconstructive abilities (P > 0.05) which were impaired compared with healthy controls. Significant differences (P < 0.05) on domains of attention, planning time and visual memory were noted between FDRs and patients.

CONCLUSION

The present study supports set-shifting and inhibitory control and proposes visuoconstructive abilities and delayed verbal recall as potential endophenotypes for OCD.

Glutamate, obsessive-compulsive disorder, schizophrenia, and the stability of cortical attractor neuronal networks

A computational neuroscience approach to the symptoms of obsessive-compulsive disorder based on a stochastic neurodynamical framework is described. An increased depth in the basins of attraction of attractor neuronal network states in the brain makes each state too stable, so that it tends to remain locked in that state, and cannot easily be moved on to another state. It is suggested that the different symptoms that may be present in obsessive--compulsive disorder could be related to changes of this type in different brain regions. In integrate-and-fire network simulations, an increase in the NMDA and/or AMPA receptor conductances, which increases the depth of the attractor basins, increases the stability of attractor networks, and makes them less easily moved on to another state by a new stimulus. Increasing GABA-receptor activated currents can partly reverse this overstability. There is now some evidence for overactivity in glutamate transmitter systems in obsessive-compulsive disorder, and the hypothesis presented here shows how some of the symptoms of obsessive-compulsive disorder could be produced by the increase in the stability of attractor networks that is produced by increased glutamatergic activity. In schizophrenia, a reduction of the firing rates of cortical neurons caused for example by reduced NMDA receptor function, present in schizophrenia, can lead to instability of the high firing rate attractor states that normally implement short-term memory and attention, contributing to the cognitive and negative symptoms of schizophrenia. Reduced cortical inhibition caused by a reduction of GABA neurotransmission, present in schizophrenia, can lead to instability of the spontaneous firing states of cortical networks, leading to a noise-induced jump to a high firing rate attractor state even in the absence of external inputs, contributing to the positive symptoms of schizophrenia.