Frontal lobe dysfunction in obsessive-compulsive disorder and major depression: a clinical-neuropsychological study

The time scales of irreversibility in spontaneous brain activity are altered in obsessive compulsive disorder

We study how obsessive-compulsive disorder (OCD) affects the complexity and time-reversal symmetry-breaking (irreversibility) of the brain resting-state activity as measured by magnetoencephalography (MEG). Comparing MEG recordings from OCD patients and age/sex matched control subjects, we find that irreversibility is more concentrated at faster time scales and more uniformly distributed across different channels of the same hemisphere in OCD patients than in control subjects. Furthermore, the interhemispheric asymmetry between homologous areas of OCD patients and controls is also markedly different. Some of these differences were reduced by 1-year of Kundalini Yoga meditation treatment. Taken together, these results suggest that OCD alters the dynamic attractor of the brain's resting state and hint at a possible novel neurophysiological characterization of this psychiatric disorder and how this therapy can possibly modulate brain function.

Exploratory Analysis of Behavioral Impulsivity, Pro-inflammatory Cytokines, and Resting-State Frontal EEG Activity Associated With Non-suicidal Self-Injury in Patients With Mood Disorder

Introduction: Non-suicidal self-injury (NSSI) is a rapidly increasing mental health problem that requires more clinical attention. In this study, we aimed to explore the biobehavioral markers of NSSI in participants with mood disorders. Methods: A total of 45 participants with mood disorders (bipolar I, II, and major depressive disorder) were included in the study. Behavioral impulsivity was measured using the immediate memory task (IMT)/delayed memory task (DMT) and the go-no-go (GNG) tests. Plasma levels of tumor necrosis factor-α (TNF-α), interleukin 1 beta (IL-1 β), and interleukin 6 (IL-6) and resting-state quantitative electroencephalography (qEEG) were measured. Results: The NSSI group had shorter GNG reaction time (GNG-RT) and higher TNF-α levels compared to the non-NSSI group. TNF-α was positively correlated with frontal theta power. In addition, GNG-RT showed a significant positive association with frontal alpha activity. Conclusion: NSSI in mood disorders was associated with increased behavioral impulsivity and greater inflammation. Increased pro-inflammatory cytokines were associated with frontal theta power. Increased inflammation might change major neurotransmitter metabolism, which eventually affects frontal function and decreases response inhibition. Further studies to explore their causal relationship are warranted.

Behavioral flexibility in a mouse model for obsessive-compulsive disorder: Impaired Pavlovian reversal learning in SAPAP3 mutants

Obsessive-compulsive disorder (OCD) is characterized by obsessive thinking, compulsive behavior and anxiety, and is often accompanied by cognitive deficits. The neuropathology of OCD involves dysregulation of cortical-striatal circuits. Similar to OCD patients, SAPAP3 knockout mice 3 (SAPAP3-/- ) exhibit compulsive behavior (grooming), anxiety and dysregulated cortical-striatal function. However, it is unknown whether SAPAP3-/- display cognitive deficits and how these different behavioral traits relate to one another. SAPAP3-/- and wild-type (WT) littermates were trained in a Pavlovian conditioning task pairing visual cues with the delivery of sucrose solution. After mice learned to discriminate between a reward-predicting conditioned stimulus (CS+) and a non-reward stimulus (CS-), contingencies were reversed (CS+ became CS- and vice versa). Additionally, we assessed grooming, anxiety and general activity. SAPAP3-/- acquired Pavlovian approach behavior similarly to WT, albeit less vigorously and with a different strategy. However, unlike WT, SAPAP3-/- were unable to adapt their behavior after contingency reversal, exemplified by a lack of re-establishing CS+ approach behavior (sign tracking). Surprisingly, such behavioral inflexibility, decreased vigor, compulsive grooming and anxiety were unrelated. This study shows that SAPAP3-/- are capable of Pavlovian learning, but lack flexibility to adapt associated conditioned approach behavior. Thus, SAPAP3-/- not only display compulsive-like behavior and anxiety, but also cognitive deficits, confirming and extending the validity of SAPAP3-/- as a suitable model for the study of OCD. The observation that compulsive-like behavior, anxiety and behavioral inflexibility were unrelated suggests a non-causal relationship between these traits and may be of clinical relevance for the treatment of OCD.

Executive Functions of Obsessive Compulsive Disorder and Panic Disorder Patients in Comparison to Healty Controls

Introduction

Patients with obsessive compulsive disorder (OCD) have impaired cognitive functions, including attention, verbal and visual memory, and visual-spatial abilities as well as executive function But some studies did not show any disturbance in executive function of patients with OCD. To date, only few studies have been conducted on neuropsychological functioning of patients with panic disorder (PD). There are limited studies to reach a definite conclusion on executive functions of patients with OCD and those with PD. In this study, we aimed to measure executive functions of patients with OCD and those with PD compared with those of healthy controls. Although there are many studies on cognitive functions of patients with OCD, there appears to be no consistency in results and no findings have been obtained to enable us to reach definite conclusions. Although there are very few studies on neuropsychological functions of patients with PD, impairments on a set of cognitive functions have been demonstrated. To date, no finding with respect to impairment in executive functions of patients with PD has been published. PD and OCD are disorders manifesting similar characteristics, with the presence of anxiety and avoidance behavior. Besides this, patients with OCD also have symptoms such as obsessions and compulsions that are characteristics of this disorder. We aim to compare executive functions in the three groups (patients with OCD, those with PD, and healthy controls) in this study.

Method

Seventeen patients with OCD and 15 patients with PD who were diagnosed according to Diagnostic and Statistical Manual of Mental Disorder -IV-TR (DSM-IV-TR) and 26 healthy control subjects were included in this study. Patients who used medication as well as those with medical illnesses and Axis-I comorbidities were excluded. The healthy control group subjects were matched with the patients in terms of age, gender, and education. Structured Clinical Interview for DSM-IV Axis-I Disorders-Clinical Version (SCID-I), Hamilton Depression Rating Scale (HDRS), and Yale-Brown obsessive compulsive scale tests (Y-BOCS) were administered to the patients. Trail Making Tests (TMT), verbal fluency tests (Controlled Oral Word Association Test and Categorical Naming), Stroop Test, and Wisconsin Card Sorting Test (WCST) were administered to the study groups.

Results

According to our results, there was no statistically significant difference between the three study groups with respect to executive functions. There was also no significant correlation between executive tests' results and Y-BOCS'in the OCD group.

Conclusion

The results of the PD group are in line with that reported in literature. The results of the OCD group can be explained by a lack of medication usage and any comorbidity including depression. A small sample size is the major limitation of our study.

Modulations of cognitive flexibility in obsessive compulsive disorder reflect dysfunctions of perceptual categorization

BACKGROUND

Despite cognitive inflexibility is trait like in obsessive compulsive disorder (OCD) patients and underlies clinical symptomatology, it is elusive at what stage of information processing deficits, leading to cognitive inflexibility, emerges. We hypothesize that inhibitory control mechanisms during early stimulus categorization and integration into a knowledge system underlie these deficits.

METHODS

We examined N = 25 adolescent OCD patients and matched healthy controls (HC) in a paradigm manipulating the importance of the knowledge system to perform task switching. This was done using a paradigm in which task switches were signaled either by visual stimuli or by working memory processes. This was combined with event-related potential recordings and source localization.

RESULTS

Obsessive compulsive disorder patients showed increased switch costs in the memory as compared with the cue-based block, while HC showed similar switch costs in both blocks. At the neurophysiological level, these changes in OCD were not reflected by the N2 and P3 reflecting response-associated processes but by the P1 reflecting inhibitory control during sensory categorization processes. Activation differences in the right inferior frontal gyrus and superior temporal gyrus are associated with the P1 effect.

CONCLUSIONS

Cognitive flexibility in adolescent OCD patients is strongly modulated by working memory load. Contrary to common sense, not response-associated processes, but inhibitory control mechanisms during early stimulus categorization processes are likely to underlie cognitive inflexibility in OCD. These processes are associated with right inferior frontal and superior temporal gyrus mechanisms.

Decreased global field synchronization of multichannel frontal EEG measurements in obsessive-compulsive disorders

Global field synchronization (GFS) quantifies the synchronization level of brain oscillations. The GFS method has been introduced to measure functional synchronization of EEG data in the frequency domain. GFS also detects phase interactions between EEG signals acquired from all of the electrodes. If a considerable amount of local brain neurons has the same phase, these neurons appear to interact with each other. EEG data were received from 17 obsessive-compulsive disorder (OCD) patients and 17 healthy controls (HC). OCD effects on local and large-scale brain circuits were studied. Analysis of the GFS results showed significantly decreased values in the delta and full frequency bands. This research suggests that OCD causes synchronization disconnection in both the frontal and large-scale regions. This may be related to motivational, emotional and cognitive dysfunctions.

Over facilitation of unadapted cognitive processes in obsessive compulsive disorder as assessed with the computerized mirror pointing task

Response inhibition has been suggested to be dysfunctional in obsessive-compulsive disorder (OCD). However, this process involves intentional cognitive control, which does not correspond to the automatic emergence of stereotyped thoughts and behaviours usually reported by patients with OCD. In the present study, the excessive facilitation of unintentional processes was assessed in OCD by using the Computerized Mirror Pointing Task (CMPT). Seventy-six volunteers participated in this study, including 39 patients with OCD and 37 healthy controls. The CMPT was administered to all participants, and a score of appropriateness of the sensorimotor adaptation to the mirror inversion was computed from the initial deviation angle (IDA), that precedes the intentional readjustment of movement. Results showed that throughout the 40 trials of the CMPT, the IDA score remained significantly abnormal in patients with OCD in comparison with control participants. Further analyses of IDA scores in OCD revealed a clear tendency to keep a natural visuomotor processing that is rigid and unadapted to the mirror condition. Irrespective of the physical requirements of the environment, patients with OCD showed a strong tendency to initiate movements as per a previously consolidated - although unadapted - sensorimotor mapping. This suggests a tendency for an excessive facilitation of unintentional stereotyped processes. Further studies should be conducted on this question by using tasks sensitive to cognitive processes other than visuo-spatial abilities.

Classification of Obsessive Compulsive Disorder by EEG Complexity and Hemispheric Dependency Measurements

In the present study, both single channel electroencephalography (EEG) complexity and two channel interhemispheric dependency measurements have newly been examined for classification of patients with obsessive–compulsive disorder (OCD) and controls by using support vector machine classifiers. Three embedding entropy measurements (approximate entropy, sample entropy, permutation entropy (PermEn)) are used to estimate single channel EEG complexity for 19-channel eyes closed cortical measurements. Mean coherence and mutual information are examined to measure the level of interhemispheric dependency in frequency and statistical domain, respectively for eight distinct electrode pairs placed on the scalp with respect to the international 10–20 electrode placement system. All methods are applied to short EEG segments of 2 s. The classification performance is measured 20 times with different 2-fold cross-validation data for both single channel complexity features (19 features) and interhemispheric dependency features (eight features). The highest classification accuracy of 85 ±5.2% is provided by PermEn at prefrontal regions of the brain. Even if the classification success do not provided by other methods as high as PermEn, the clear differences between patients and controls at prefrontal regions can also be obtained by using other methods except coherence. In conclusion, OCD, defined as illness of orbitofronto-striatal structures [Beucke et al., JAMA Psychiatry 70 (2013) 619–629; Cavedini et al., Psychiatry Res. 78 (1998) 21–28; Menzies et al., Neurosci. Biobehav. Rev. 32(3) (2008) 525–549], is caused by functional abnormalities in the pre-frontal regions. Particularly, patients are characterized by lower EEG complexity at both pre-frontal regions and right fronto-temporal locations. Our results are compatible with imaging studies that define OCD as a sub group of anxiety disorders exhibited a decreased complexity (such as anorexia nervosa [Toth et al., Int. J. Psychophysiol. 51(3) (2004) 253–260] and panic disorder [Bob et al., Physiol. Res. 55 (2006) S113–S119]).

Mediodorsal thalamus hypofunction impairs flexible goal-directed behavior

BACKGROUND

Cognitive inflexibility is a core symptom of several mental disorders including schizophrenia. Brain imaging studies in schizophrenia patients performing cognitive tasks have reported decreased activation of the mediodorsal thalamus (MD). Using a pharmacogenetic approach to model MD hypofunction, we recently showed that decreasing MD activity impairs reversal learning in mice. While this demonstrates causality between MD hypofunction and cognitive inflexibility, questions remain about the elementary cognitive processes that account for the deficit.

METHODS

Using the Designer Receptors Exclusively Activated by Designer Drugs system, we reversibly decreased MD activity during behavioral tasks assessing elementary cognitive processes inherent to flexible goal-directed behaviors, including extinction, contingency degradation, outcome devaluation, and Pavlovian-to-instrumental transfer (n = 134 mice).

RESULTS

While MD hypofunction impaired reversal learning, it did not affect the ability to learn about nonrewarded cues or the ability to modulate action selection based on the outcome value. In contrast, decreasing MD activity delayed the ability to adapt to changes in the contingency between actions and their outcomes. In addition, while Pavlovian learning was not affected by MD hypofunction, decreasing MD activity during Pavlovian learning impaired the ability of conditioned stimuli to modulate instrumental behavior.

CONCLUSIONS

Mediodorsal thalamus hypofunction causes cognitive inflexibility reflected by an impaired ability to adapt actions when their consequences change. Furthermore, it alters the encoding of environmental stimuli so that they cannot be properly utilized to guide behavior. Modulating MD activity could be a potential therapeutic strategy for promoting adaptive behavior in human subjects with cognitive inflexibility.

Is obsessive-compulsive symptomatology a risk factor for Alzheimer-type dementia?

In the present study, we hypothesized that lifetime Obsessive-Compulsive (OC) symptomatology would be risk factors for the development of Alzheimer׳s disease (AD). For this aim, first we compared 39 patients with AD and 30 age and gender matched control subjects. We have found that lifetime and current OC symptoms (OCs) and comorbid diagnosis of Obsessive-Compulsive Personality Disorder in AD patients were significantly more prevalent than in control group. AD patients had more likely to have lifetime and current hoarding, and checking obsessions compared to controls. The rate of lifetime and current hoarding, and checking compulsions also appeared to be higher in AD patients in comparison to control subjects. Hoarding and checking obsessions, and compulsions seemed to proceed through the dementia in contrast to other OCs. The mean number of lifetime compulsions seemed to predict the diagnosis of AD. When we compared AD patients with and without OCs, we have found that OC symptomatology prior to AD did not cause an earlier onset of dementia and more severe cognitive impairment. Further longitudinal clinical, genetic and neuroimaging investigations are required to determine if lifetime presence of OCs would predispose to the development of later AD.

Neurobiological model of obsessive-compulsive disorder: evidence from recent neuropsychological and neuroimaging findings

Obsessive-compulsive disorder (OCD) was previously considered refractory to most types of therapeutic intervention. There is now, however, ample evidence that selective serotonin reuptake inhibitors and behavior therapy are highly effective methods for treatment of OCD. Furthermore, recent neurobiological studies of OCD have found a close correlation between clinical symptoms, cognitive function, and brain function. A large number of previous neuroimaging studies using positron emission tomography, single-photon emission computed tomography or functional magnetic resonance imaging (fMRI) have identified abnormally high activities throughout the frontal cortex and subcortical structures in patients with OCD. Most studies reported excessive activation of these areas during symptom provocation. Furthermore, these hyperactivities were decreased after successful treatment using either selective serotonin reuptake inhibitors or behavioral therapy. Based on these findings, an orbitofronto-striatal model has been postulated as an abnormal neural circuit that mediates symptomatic expression of OCD. On the other hand, previous neuropsychological studies of OCD have reported cognitive dysfunction in executive function, attention, nonverbal memory, and visuospatial skills. Moreover, recent fMRI studies have revealed a correlation between neuropsychological dysfunction and clinical symptoms in OCD by using neuropsychological tasks during fMRI. The evidence from fMRI studies suggests that broader regions, including dorsolateral prefrontal and posterior regions, might be involved in the pathophysiology of OCD. Further, we should consider that OCD is heterogeneous and might have several different neural systems related to clinical factors, such as symptom dimensions. This review outlines recent neuropsychological and neuroimaging studies of OCD. We will also describe several neurobiological models that have been developed recently. Advanced findings in these fields will update the conventional biological model of OCD.

Psychiatric disorders and muscle tenderness in episodic and chronic migraine

This review first reports on the data concerning the relationship between migraine and personality traits and psychiatric disorders. The relationship between migraine and tenderness of the pericranial and cervical muscles is then discussed. In one study, a psychologic assessment was performed in 56 women with migraine, and the Minnesota Multiphase Personality Inventory (MMPI) and State Trait Anxiety Inventory were administered at baseline (T0) and after 6-7 years (T2). Frequency, severity and duration of migraine were recorded at T0, after treatment (T1) and at T2, and their relationship to the prevalence of depression, MMPI and State Trait Anxiety Inventory data were examined. Pain parameters improved in all patients in T0-1, but were higher at T2 in patients with depression at T0. The patients whose migraine improved at T2 had significantly lower MMPI and State Trait Anxiety Inventory scores at T0 and T2. Moreover, the prevalence of depression of the patients whose migraine improved at T2 was 37.5% at T0 and decreased to 12.5% at T2. The authors subsequently studied the function of the frontal lobe in 23 female patients previously treated for chronic migraine and 23 controls by applying three neuropsychologic tests (gambling task, tower of hanoi-3 and object alternation test). The patient group performed significantly worse on the tower of hanoi-3 and the object alternation test. In order to assess the extent to which muscle tenderness may relate to psychiatric disorders in patients with migraine and tension-type headache, diagnosed according International Headache Society criteria [2004], a psychologic assessment was performed and palpation tenderness scores calculated for the pericranial and cervical muscles in 459 patients. In total, 125 patients had frequent episodic migraine, 97 had chronic migraine, 82 had frequent episodic tension-type headache and chronic tension-type headache was present in 83. In a further 72 patients, both episodic migraine and episodic tension-type headache were present. The main finding was a positive relationship between muscle tenderness and psychiatric disorders in patients with episodic migraine alone or associated with episodic tension-type headache.

Dopaminergic control of cognitive flexibility in humans and animals

Striatal dopamine (DA) is thought to code for learned associations between cues and reinforcers and to mediate approach behavior toward a reward. Less is known about the contribution of DA to cognitive flexibility—the ability to adapt behavior in response to changes in the environment. Altered reward processing and impairments in cognitive flexibility are observed in psychiatric disorders such as obsessive compulsive disorder (OCD). Patients with this disorder show a disruption of functioning in the frontostriatal circuit and alterations in DA signaling. In this review we summarize findings from animal and human studies that have investigated the involvement of striatal DA in cognitive flexibility. These findings may provide a better understanding of the role of dopaminergic dysfunction in cognitive inflexibility in psychiatric disorders, such as OCD.

Obsessive and compulsive symptoms in a national sample of older people: prevalence, comorbidity, and associations with cognitive function

OBJECTIVES

To describe the prevalence of obsessive and compulsive symptoms in a national community sample of older adults, their comorbidity with mental disorders, and associations with cognitive impairment.

DESIGN

A secondary analysis of data from a national survey.

SETTING

The 2000 British National Psychiatric Morbidity Survey.

PARTICIPANTS

Primary analyses focused on 2,007 60- to 74-year-old community residents; secondary analyses compared these with 6,573 younger survey participants age 16-59 years.

MEASUREMENTS

Obsessive and compulsive symptoms and mental disorders, including International Classification of Diseases, Tenth Revision (ICD-10) obsessive-compulsive disorder, were ascertained from the revised Clinical Interview Schedule and cognitive function from the modified Telephone Interview for Cognitive Status (global function, immediate and delayed word recall), verbal fluency (animal naming), and National Adult Reading Test (estimated verbal IQ). Health-related quality of life (SF12) was measured in addition to subjective impact.

RESULTS

One-month prevalences of obsessive and compulsive symptoms and obsessive-compulsive disorder were 4.7%, 2.2%, and 0.4%, respectively (compared with 5.9%, 3.2%, and 0.8% in younger participants). High levels of comorbidity were found. Obsessive and compulsive symptoms were described as distressing by 67.8% and 70.2%, respectively, and both were associated with worse mental health-related quality of life. Obsessive symptoms were associated with lower verbal IQ and also with lower verbal fluency, which was not accounted for by education or estimated verbal IQ.

CONCLUSIONS

Obsessions and compulsions had significant prevalence in this national older population. Consistent with previous reports, relative impairment in executive function (verbal fluency) was found in people reporting these symptoms.

The extended fronto-striatal model of obsessive compulsive disorder: convergence from event-related potentials, neuropsychology and neuroimaging

In this work, we explored convergent evidence supporting the fronto-striatal model of obsessive-compulsive disorder (FSMOCD) and the contribution of event-related potential (ERP) studies to this model. First, we considered minor modifications to the FSMOCD model based on neuroimaging and neuropsychological data. We noted the brain areas most affected in this disorder -anterior cingulate cortex (ACC), basal ganglia (BG), and orbito-frontal cortex (OFC) and their related cognitive functions, such as monitoring and inhibition. Then, we assessed the ERPs that are directly related to the FSMOCD, including the error-related negativity (ERN), N200, and P600. Several OCD studies present enhanced ERN and N2 responses during conflict tasks as well as an enhanced P600 during working memory (WM) tasks. Evidence from ERP studies (especially regarding ERN and N200 amplitude enhancement), neuroimaging and neuropsychological findings suggests abnormal activity in the OFC, ACC, and BG in OCD patients. Moreover, additional findings from these analyses suggest dorsolateral prefrontal and parietal cortex involvement, which might be related to executive function (EF) deficits. Thus, these convergent results suggest the existence of a self-monitoring imbalance involving inhibitory deficits and executive dysfunctions. OCD patients present an impaired ability to monitor, control, and inhibit intrusive thoughts, urges, feelings, and behaviors. In the current model, this imbalance is triggered by an excitatory role of the BG (associated with cognitive or motor actions without volitional control) and inhibitory activity of the OFC as well as excessive monitoring of the ACC to block excitatory impulses. This imbalance would interact with the reduced activation of the parietal-DLPC network, leading to executive dysfunction. ERP research may provide further insight regarding the temporal dynamics of action monitoring and executive functioning in OCD.

Early orbitofrontal hyperactivation in obsessive-compulsive disorder

Dysfunctional activity in the orbitofrontal cortex (OFC) is one of the core features in the pathophysiology of obsessive-compulsive disorder (OCD). Neuroimaging studies indicate orbitofrontal hyperactivation during the resting state as well as during symptom provocation, whereas orbitofrontal hypoactivation has been reported during tasks designed to dissociate specific cognitive processes. Combined magnetoencephalic and functional magnetic resonance imaging studies show early involvement of the OFC in stimulus processing in healthy subjects. However, it is unclear whether OFC activation is dysfunctional at an early stage in patients with OCD. We investigated early electrical OFC activation evoked by reward and punishment feedback in a visual probabilistic object reversal task (pORT). Patients with OCD (n=23) and healthy controls (n=27), matched for gender, age and educational level, performed the pORT during a 29-channel electroencephalographic recording. Low resolution brain electromagnetic tomography was applied to localize orbitofrontal sources of neuronal activity at 80 to 200 ms post-stimulus. Group comparison showed significantly higher orbitofrontal activation in OCD patients at 100-120 ms after the reward stimulus. No group differences were found with respect to OFC activation in response to punishment stimuli and in task performance. Results substantiate dysfunctional OFC activity at a very early stage in the processing of reward stimuli in patients with OCD. Our results provide support for the assumption that the OFC plays a more active role in the processing of visual stimuli as previously supposed. As orbitofrontal hyperactivation following rewarding feedback occurred as early as 100 ms after receipt of the visual stimulus in patients with OCD, and as we did not find any OFC dysfunction following negative feedback, our findings may point towards a specific early disturbance of reward processing in OCD. This finding might have implications for cognitive behavioural therapy of this disorder.

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.

Impaired executive functions in paediatric obsessive-compulsive disorder patients

Isık Taner Y, Erdogan Bakar E, Oner O. Impaired executive functions in paediatric obsessive-compulsive disorder patients.

Objective: There are only few studies which investigated the neuropsychological performances of paediatric patients with obsessive-compulsive disorder (OCD). Previous studies show that most of adult OCD patients had an onset of their first symptoms before the age of 15. Our objective was to evaluate the neuropsychological functions in paediatric patients with OCD.

Methods: We compared the executive functions and general intelligence of child and adolescent OCD patients (n = 20) with age- and gender-matched healthy controls (n = 20). To compare mentioned skills, a neuropsychological test battery including Wechsler Intelligence Scale for Children-Revised (WISC-R), Wisconsin Card Sorting Test (WCST), Stroop Test and Verbal Fluency Test was performed.

Result: Performances of the OCD and control subjects on neuropsychological tests were statistically analysed by using multivariate analysis of covariance (MANCOVA), in which Full Scale Intelligence Quotient (FSIQ) results were taken into consideration as a covariate to observe FSIQ's effect on test scores. Our results showed that the differences in WISC-R Picture Arrangement and Coding scores remained significant when co-analysed with FSIQ scores. In a similar manner, the OCD group exhibited worse performances on STR1-duration, STR3-duration, STR3-error, STR4-duration, STR4-error, STR5-correct response, and STR5-error as compared with the control group when FSIQ scores were taken into calculation. Some variables of the WCST (perseverative responses, percent errors, abstraction-flexibility and categories completed) also yield lower test scores in the OCD group. There was no significant difference between the groups regarding Verbal Fluency Test scores.

Conclusion: Our results suggested that paediatric OCD patients had worse abstraction-flexibility, mental set-shifting, verbal comprehension and visuospatial/construction abilities.

Obsessive beliefs and neurocognitive flexibility in obsessive-compulsive disorder

A substantial proportion of individuals with obsessive-compulsive disorder (OCD) do not endorse the dysfunctional beliefs proposed by cognitive models of OCD to be important in the onset and maintenance of symptoms. Previous research has attempted to characterize Low and High obsessive beliefs groups in terms of cognitive and symptom correlates to distil potential etiological differences in these subgroups of OCD patients. The current study sought to further examine potential neurocognitive differences between obsessive beliefs subgroups. Performance on the Wisconsin Card Sorting Test (WCST) was compared between a Low Beliefs OCD subgroup, a High Beliefs OCD subgroup, and two anxious control groups: Panic Disorder with Agoraphobia (PDA) and Social Phobia (SP). The High Beliefs OCD subgroup performed significantly poorer on WCST subscales compared to the other diagnostic groups. These findings were not accounted for by severity of OCD or depressive symptoms. The Low Beliefs OCD subgroup performed similar to the anxiety disorder control groups. The results suggest a potential interplay between heightened obsessive beliefs and neurocognitive inflexibility.

Perseveration on a reversal-learning task correlates with rates of self-directed behavior in nonhuman primates

In humans and several nonhuman animals, repetitive behavior is associated with deficits on executive function tasks involving response inhibition. We tested for this relationship in nonhuman primates by correlating rates of normative behavior to performance on a reversal-learning task in which animals were required to inhibit a previously learned rule. We focused on rates of self-directed behavior (scratch, autogroom, self touch and manipulation) because these responses are known indicators of arousal or anxiety in primates, however, we also examined rates of other categories of behavior (e.g., locomotion). Behavior rates were obtained from 14 animals representing three nonhuman primate species (Macaca silenus, Saimiri sciureus, Cebus apella) living in separate social groups. The same animals were tested on a reversal-learning task in which they were presented with a black and a grey square on a touch screen and were trained to touch the black square. Once animals learned to select the black square, reward contingencies were reversed and animals were rewarded for selecting the grey square. Performance on the reversal-learning task was positively correlated to self-directed behavior in that animals that exhibited higher rates of self-directed behavior required more trials to achieve reversal. Reversal learning was not correlated to rates of any other category of behavior. Results indicate that rates of behavior associated with anxiety and arousal provide an indicator of executive function in nonhuman primates. The relationship suggests continuity between nonhuman primates and humans in the link between executive functioning and repetitive behavior.

Dissociation of decisions in ambiguous and risky situations in obsessive-compulsive disorder

Patients with obsessive-compulsive disorder (OCD) often show deficits in everyday decision-making, a phenomenon which is leading to a growing research interest in neuropsychological aspects of decision-making in OCD. Previous investigations of OCD patients demonstrated deficits in the Iowa Gambling Task (IGT), a decision-making task with implicit rules. Results were interpreted as reflecting orbitofrontal cortex dysfunctions observed in OCD. The aim of the present study is to investigate OCD patients' performance on the Game of Dice Task (GDT), a decision-making task with explicit and stable rules. For this purpose, 23 patients with OCD and 22 healthy comparison subjects were examined with the GDT and the IGT as well as with tests of executive functioning. While patients performed worse than comparison subjects on the IGT, they were unimpaired on the GDT and executive functioning tasks. Results further emphasize dysfunctions of the orbitofrontal cortex, but indicate intact functioning of the dorsolateral prefrontal cortex in patients with OCD.

Cross-species models of OCD spectrum disorders

Several axis-I neuropsychiatric disorders are characterised by repetitive motor habits suggestive of underlying inhibitory dyscontrol, and may constitute members of a putative obsessive-compulsive (OC) spectrum. Notable examples include obsessive-compulsive disorder (OCD) and trichotillomania (repetitive hair-pulling). Multiple tiers of evidence link these conditions with underlying dysregulation of fronto-striatal circuitry and monoamine systems. These abnormalities represent key targets for existing and novel treatment interventions. Nonetheless, the brain bases of these conditions, and treatment mechanisms, remain poorly characterised. Animal models of repetitive habits and inhibitory control problems show great potential for augmenting our understanding of the pathophysiology and treatment of OC spectrum conditions. Here, we begin by describing clinical features of OC spectrum disorders, and 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) behavioral models. Key future research directions are highlighted.

Working memory dysfunction in obsessive-compulsive disorder: a neuropsychological and functional MRI study

Previous neuropsychological studies indicate that OCD subtypes such as checking rituals might be associated with a working memory deficit. On the other hand, functional neuroimaging studies found functional abnormalities of the frontal cortex and subcortical structures in OCD. Combined with functional imaging method, we applied neuropsychological batteries to demonstrate a working memory deficit in OCD by comparison with normal controls. In addition, working memory and brain activation were further examined with symptom-based analysis. Forty patients with OCD and 25 normal controls were examined using neuropsychological tests including the WAIS-R, WCST, WMS-R, and R-OCFT and functional MRI (fMRI) during the N-back task including 0- and 2-back task. On fMRI, the brain regions activated during the performance and the differences in the activation between patients and controls were identified. Additional analyses of severity and subtypes were conducted by using Y-BOCS severity score, symptom-checklist and Leckman's four-factor model, respectively. On the neuropsychological tests, the OCD patients had significantly lower scores on the delayed recall section of the WMS-R and the immediate recall section of the R-OCFT compared to the controls. On fMRI, the patients showed greater activation in the right dorsolateral prefrontal cortex (DLPFC), left superior temporal gyrus (STG), left insula, and cuneus during two-back task compared to the controls. Right orbitofrontal cortex activity showed a significant positive correlation with Y-BOCS scores in OCD. Furthermore, patients with obsessions/checking rituals (n=10) showed severer memory deficits and decreased activity in the postcentral gyrus than patients with cleanliness/washing rituals (n=14). In conclusion, we found neuropsychological dysfunction and brain abnormalities in OCD. Furthermore, our results suggested that symptom severity and symptom subtype such as obsessions/checking might affect neuropsychological dysfunction and related brain activities.

No deficits in nonverbal memory, metamemory and internal as well as external source memory in obsessive-compulsive disorder (OCD)

A large body of literature suggests that some symptoms of obsessive-compulsive disorder (OCD) result from mnemonic dysfunctions. The present study tested various formulations of the memory deficit hypothesis considering important moderators, such as depression and response slowing. Thirty-two OCD patients and 32 healthy controls were presented verbal or nonverbal instructions for actions (e.g. simple gestures). These actions should either be performed or imagined. For recognition, previously presented as well as novel actions were displayed. Decisions had to be made whether an action was previously displayed (verbally vs. nonverbally) or not and whether an action was performed or imagined (internal source memory). Moreover, both judgments required confidence ratings. Groups did not differ in memory accuracy and metamemory for verbally presented material. Patients displayed some impairment for nonverbally presented material and imagined instructions, which, however, could be fully accounted for by response slowing and depressive symptoms. The study challenges the view that primary memory deficits underlie OCD or any of its subtypes. We claim that research should move forward from the mere study of objective impairment to the assessment of cognitive performance in conjunction with personality traits such as inflated responsibility.

Performance of patients with refractory obsessive-compulsive disorder in the Frontal Systems Behavior Scale

OBJECTIVE

To compare the performance of patients with obsessive-compulsive disorder (OCD) refractory to conventional treatments to healthy controls according to the Frontal Systems Behaviour Scale (FrSBe), comparing the scale scores within each group (Self or Family) and correlating FrSBe with Y-BOCS, DY-BOCS, tic disorder and age of first symptoms.

METHOD

Twenty OCD patients and 20 healthy controls were assessed using the FrSBe, a scale designed to evaluate frontal syndromes.

RESULTS

The patients had higher scores when compared with the control group (p value < .001) in terms of total score on the scale for both profile forms (Self and Family). In addition, there was a significant difference between the scores reported by the patients and their respective relatives. However, no correlation was observed between the scale and the other variables.

CONCLUSIONS

The scale was able to clearly differentiate patients with OCD from healthy controls. This finding suggests that the FrSBe can be used not only in neurologic patients but also in psychiatric cases such as refractory OCD.

Gray matter structural alterations in obsessive-compulsive disorder: relationship to neuropsychological functions

Numerous magnetic resonance (MR) studies have examined gray matter structural alterations in patients with obsessive-compulsive disorder (OCD). Few, however, have used automated, highly reliable techniques such as voxel-based morphometry (VBM) to examine the entire brain in contrast to selected regions of interest. Moreover, few studies have examined the functional correlates of gray matter abnormalities in OCD. We used VBM to evaluate regional gray matter differences between 21 OCD patients and 21 age- and sex-matched healthy volunteers. All patients had comprehensive neuropsychological assessments. MR images were normalized to a customized template and segmented using optimized VBM. OCD patients had significantly more gray matter in the left thalamus compared with healthy volunteers. OCD patients without major depression had significantly more gray matter in the thalamus (bilaterally) and left orbitofrontal cortex as well as an unpredicted region of more right dorsolateral prefrontal gray matter, which remained significant after correction for multiple comparisons, compared with healthy volunteers. In the subgroup of patients without depression, greater right hemisphere thalamic and dorsolateral prefrontal gray matter correlated significantly with worse motor functioning and processing speed, respectively. In this subgroup there was also a tendency for more gray matter in the left orbitofrontal cortex and right dorsolateral prefrontal cortex to be associated with greater symptom severity. Our findings provide additional support for the involvement of cortical-striatal-thalamic circuits in the pathophysiology of OCD and preliminary evidence that a defect involving the dorsolateral prefrontal cortex may also be implicated. Moreover, our data suggest that gray matter structural alterations in OCD have neuropsychological correlates, which may be useful in further characterizing structure-function relations in this disorder.

A study of neuropsychological deficit in children with obsessive-compulsive disorder

This study was conducted to examine the neuropsychological deficits in children with obsessive compulsive disorder (OCD). Furthermore, the focus of present study was to explore whether OCD children show the same executive dysfunction as adult OCD patients. The participants consisted of 106 children between the ages of 6 and 16 years who visited the department of child-adolescent psychiatry, Seoul National University Children's Hospital (17 OCD, 25 ADHD, 21 tic disorder, 20 depressive disorder, and 23 healthy children). The OCD children showed higher verbal ability compared to other psychiatric groups, but performed the worst on WISC-R subtests assessing perceptual organization ability under time pressure. The OCD children did not show any significant deficits in verbal intellectual function, memory, attention and concentration abilities. However, similar to the ADHD children, the OCD children had significantly more errors and completed fewer categories on the WCST compared to the healthy group. Through neuropsychological tests, the OCD children showed cognitive strength and weakness similar to those of OCD adults that were reported in previous research. Specifically, they had executive function deficits in mental set shifting, supporting the frontal-striatal dysfunction hypothesis of OCD in children as well as in adults.

Neurocognitive correlates of child obsessive compulsive disorder and Tourette syndrome

This study investigated the neurocognitive correlates of childhood OCD and TS, which are purported to share frontal-striatal dysfunction. Neurocognitive measures tapping frontal-striatal functions such as executive, attention/memory, and visuomotor abilities were administered to three groups of participants, OCD without comorbid TS (OCD), TS without comorbid OCD (TS), and normal controls. Results suggested that OCD group demonstrated deficits in the area of spatial attention relative to healthy controls. The OCD participants demonstrated no cognitive deficits compared to the TS group. TS participants showed trends towards impairments in the areas of response inhibition, divided attention, and cognitive flexibility relative to the OCD and normal control groups. Spatial attention deficits for the OCD group are partially consistent with adult OCD studies indicating deficits in spatial memory. TS findings were less robust and may be construed tentatively as suggestive of executive function deficits. Future research is needed to delineate the influence of development on neurocognitive deficits associated with OCD and TS.

Impact of coexistent schizotypal personality traits on frontal lobe function in obsessive-compulsive disorder

OBJECTIVE

This study was a post-hoc analysis of the results from a neuropsychological battery which was conducted to investigate the frontal lobe difference between obsessive-compulsive disorder (OCD) patients with and without schizotypal personality trait (SPT), especially dorsolateral prefrontal and medial frontal functions.

METHODS

Fifty-five OCD patients were divided into two groups according to their Personality Disorder Questionnaire-4+ scores. Patients with OCD with SPT (n=17) and OCD without SPT (n=38) were compared to 52 schizophrenia patients and 67 healthy subjects. Two neuropsychological tasks, the Wisconsin Card Sorting Test (WCST) and verbal fluency tests which are considered to reflect dorsolateral and medial frontal functions, were selected for an analysis.

RESULTS

OCD with SPT patients and patients with schizophrenia performed significantly worse than controls in both the WCST and verbal fluency tasks, whereas OCD without SPT patients showed no deficits in the same tasks. Moreover, we found no statistically significant difference in either task between patients having OCD with SPT and patients with schizophrenia.

CONCLUSION

This study indicate that OCD with SPT may have distinct patterns of neurocognitive deficit that differ from those of OCD without SPT, especially in terms of frontal lobe function.

Affective and neuropsychological correlates of children’s rituals and compulsive-like behaviors: Continuities and discontinuities with obsessive–compulsive disorder

This study explored the relations among ritualistic and compulsive-like behavior, fears, and neuropsychological performance in typically developing children between the ages of four and eight years. Forty-two children were administered a battery of neuropsychological tasks assessing response inhibition and set-shifting. Two parent-report questionnaires assessed the intensity of children's fears and compulsive-like behaviors ("just right" perceptions and repetitive behaviors). For younger children (72 months), set-shifting and response inhibition accounted for significant variance in their ritualistic, compulsive-like behaviors. For older children (>72 months), a combination of neuropsychological (response inhibition) and affective (animal fears and social anxiety) factors predicted compulsive-like behaviors. These findings suggest that common neuropsychological mechanisms underlie compulsive, ritualistic behavior exhibited in normal development and in obsessive-compulsive disorder.

The role of abnormal neural oscillations in the pathophysiology of co-occurring Tourette syndrome and attention-deficit/hyperactivity disorder

OBJECTIVE

To examine the role of aberrant neural oscillatory activity in the pathophysiology of co-occurring Tourette Syndrome (TS) and Attention-Deficit/Hyperactivity Disorder (ADHD).

METHOD

Neural oscillations refer to periodic variations in the recording of neural activity. The temporal synchronization of oscillations represents a mechanism of neural communication implicated in normal brain functioning as well as psychopathology. We reviewed physiological, imaging, and neuropsychological evidence that tics and symptoms of ADHD may result from abnormal oscillatory activity in the brain.

RESULTS

Structural and functional abnormalities in the cortical-striatal-thalamo-cortical circuits may result in the disruption of oscillatory activity within the basal ganglia of individuals with TS and lead to transient hyperpolarization of selected thalamocortical regions. Extended to TS plus ADHD this or similar mechanisms, in turn, would lead to the dysrhythmia of particular vulnerable cortical regions and give rise to various deficits in motor control (TS + ADHD) as well as impulsivity and attention (ADHD). Compensatory systems within the prefrontal cortex could be activated and trained to modulate the misguided striatal and thalamocortical oscillations.

CONCLUSIONS

Although it is highly likely that abnormal neural oscillations have a prominent role in co-occurrence of TS + ADHD, its final relevance in this case deserves further differentiated research (i.e. oscillatory networks disentangled from other neuropsychiatric disorders).

Electrophysiological correlates of behavioral response inhibition in patients with obsessive-compulsive disorder

In this study, we have attempted to determine the electrophysiological correlates of behavioral response inhibition in patients with obsessive-compulsive disorder (OCD). To evaluate response inhibition ability, we have used the Go/NoGo task and measured N2 and P3 event-related potential (ERP) components. Both the OCD and control groups exhibited greater and more frontally distributed N2 and P3 amplitudes in the NoGo condition compared to what we observed in the Go condition. However, the patients with OCD also manifested reduced NoGo-N2 and Go-N2 amplitudes at the frontocentral electrode sites compared to the controls. In addition, the NoGo-N2 amplitudes were more posteriorly distributed in patients with OCD than in controls. The NoGo-N2 amplitudes and latencies measured at the central sites were also negatively correlated with the obsession score on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). The OCD and control groups were comparable with regard to Go-P3 and NoGo-P3 amplitude and latencies. Our findings suggest dysfunctions in frontal regions mediating response inhibition in OCD, consistent with the involvement of response inhibition in the pathophysiology of this disorder. In addition, NoGo-N2 seems to result in more accurate response inhibition measurements in patients with OCD than does NoGo-P3.

Neurocognitive indices of executive hypercontrol in obsessive-compulsive disorder

OBJECTIVE

Cognitive impairment, more often involving memory and/or executive functions, has been reported in obsessive-compulsive (OC) patients. The present study aimed at: i) replicating, in an independent sample, previous findings by our group showing neurocognitive slowness limited to executive tasks; ii) assessing the influence of deficit in general cognitive abilities on executive dysfunction.

METHOD

A comprehensive neuropsychological battery was administered to 30 drug-free OC patients and 30 healthy controls.

RESULTS

Obsessive-compulsive patients performed worse on visuospatial tests, were slower on executive tasks, and performed worse on the Wisconsin Card Sorting Test. After covarying for Wechsler Adult Intelligence Scale-Revised performance Intellectual Quotient, a lesser degree of executive dysfunction was observed.

CONCLUSION

Obsessive-compulsive patients exhibit an impairment of executive functions, especially when tasks also require visuospatial abilities. The impairment might reflect a hyperactivity of the executive control.

Impaired response inhibition in obsessive compulsive disorder

Objective

The present study investigates different three inhibitory control functions in patients with obsessive-compulsive disorder (OCD). Selective motor response inhibition was tested in a GO/NO-GO paradigm, the inhibition of a triggered motor response in a STOP paradigm and the ability to inhibit cognitive interference in a motor STROOP paradigm.

Methods

27 patients who met DSM-IV criteria for OCD and 25 age, handedness and IQ-matched healthy control subjects were tested in the GO/NO-GO, STOP and motor STROOP tasks.

Results

OCD patients performed significantly worse than controls in the selective inhibition of their motor responses (GO/NO-GO) and in the inhibition of cognitive interference (STROOP), and also showed worse performance in suppressing previously triggered motor responses (STOP).

Conclusion

Patients with OCD are impaired in motor and cognitive inhibitory mechanisms. The findings are consistent with psychobiological and neuropsychological models of OCD suggesting impairment of frontostriatal circuitries that mediate functions of inhibitory control.

Visuospatial Abilities, Memory, and Executive Functioning in Trichotillomania and Obsessive-Compulsive Disorder

Few studies have compared neuropsychological functioning in trichotillomania (TTM) and obsessive-compulsive disorder (OCD). In OCD, most studies suggest abnormal visuospatial abilities, memory, and executive functioning. We compared 23 TTM, 21 OCD and 26 healthy control individuals on neuropsychological tasks assessing these abilities. Neither the TTM nor the OCD groups suffered from generalized neuropsychological deficits compared to the healthy control group. TTM participants showed increased perseveration on the Object Alternation Task suggesting difficulties with response flexibility. OCD participants showed impaired ability to learn from feedback on the Wisconsin Card Sorting Test. Other executive functions, as well as memory and visuospatial abilities were unimpaired in TTM and OCD. Our data suggest that TTM and OCD are characterized by different patterns of neuropsychological dysfunction.

Differentiating among prefrontal substrates in psychopathy: neuropsychological test findings

Frontal lobe and consequent executive dysfunction have long been related to psychopathy. More recently, there have been suggestions that specific regions of frontal cortex, rather than all of frontal cortex, may be implicated in psychopathy. To examine this issue, the authors presented 25 individuals with psychopathy and 30 comparison individuals with measures preferentially indexing the orbitofrontal cortex (OFC; object alternation task), dorsolateral prefrontal cortex (DLPFC; spatial alternation task), and anterior cingulate cortex (ACC; number-Stroop reading and counting tasks). The individuals with psychopathy showed significant impairment on the measure preferentially sensitive to OFC functioning. In contrast, the 2 groups did not show impairment on the measures preferentially sensitive to the functioning of the DLPFC or ACC. These results are interpreted with reference to executive dysfunction accounts of the disorder.

Understanding Obsessive–Compulsive Disorder: Focus on Decision Making

Current approaches to obsessive-compulsive disorder (OCD) have suggested that neurobiological abnormalities play a crucial role in the etiology and course of this psychiatric illness. In particular, a fronto-subcortical circuit, including the orbitofrontal cortex, basal ganglia and thalamus appears to be involved in the expression of OCD symptoms. Neuropsychological studies have also shown that patients with OCD show deficits in cognitive abilities that are strictly linked to the functioning of the frontal lobe and its related fronto-subcortical structures, such as executive functioning deficits and insufficient cognitive-behavioral flexibility. This article focuses on decision making, an executive ability that plays a crucial role in many real-life situations, whereby individuals choose between pursuing strategies of action that involve only immediate reward and others based on long-term reward. Although the role of decision-making deficits in the evolution of OCD requires further research, the collected findings have significant implications for understanding the clinical and behavioral heterogeneity that characterizes individuals with OCD.

Tourette's syndrome (TS): Cognitive performance in adults with uncomplicated TS

Tourette's syndrome (TS) is a neurodevelopmental disorder associated with frontostriatal dysfunction. The extent of any cognitive impairment associated with uncomplicated TS is unclear, as comorbid psychiatric symptomatology is thought to contribute to cognitive deficits. Previous studies have found evidence of mild performance deficits, most commonly on tasks that involve inhibitory processes. The present study evaluated this in carefully screened adult participants with TS. The findings showed the TS group to perform more poorly on one test involving behavioral inhibition (sentence completion), but did not provide strong support for an interpretation based solely on inhibitory deficits, and there was no evidence of impairment on another behavioral inhibition task (flanker test). There were also no differences between the groups on tasks involving working memory (n-back), task switching, or object alternation learning. The findings provide further evidence that uncomplicated TS is associated with only mild, circumscribed impairment. The nature of any impairment is discussed.

Tourette's syndrome: performance on tests of behavioural inhibition, working memory and gambling

BACKGROUND

Tourette's syndrome (TS) is a neurodevelopmental disorder associated with fronto-striatal dysfunction. There is debate as to the extent to which TS is associated with cognitive impairment. Some authors argue that any impairments seen are attributable to comorbid psychiatric symptomatology, whilst others have suggested that uncomplicated TS is associated with mild deficits limited primarily to inhibitory processes. The present study was designed to examine this issue using carefully screened participants with TS and experimental measures thought to involve different areas of the frontal lobes.

METHODS

Adolescents with TS who were screened for comorbid psychiatric disorder were compared with a healthy control group on a set of executive measures. Two tasks involving behavioural inhibition were used: a Sentence Completion task in which sentences had to be completed first with straightforward and then with nonsensical endings, and a Flanker task in which a central stimulus was surrounded by either compatible or incompatible flankers. Working memory was assessed using an N-back task, and reward learning was assessed using a Gambling task. Both accuracy and reaction times were measured for each task.

RESULTS

The TS group differed significantly from the control group on both the Sentence Completion task and on the Flanker task. On the Sentence Completion task, they were slower to make both sensible and nonsensical completions, and they had higher error scores on the nonsensical completions. On the Flanker task, the TS participants were less accurate than the control group, since they were poorer on the incompatible but not the compatible trials. A similar interaction with trial type was found for speed, where the TS participants were slowed more by the incompatible versus compatible trials, although overall their performance tended to be faster than the controls. The TS group did not differ significantly from the control group on measures of working memory or reward learning.

CONCLUSIONS

The findings provide further evidence that uncomplicated TS is not associated with widespread executive impairments. However, it was not clear that any differences between the groups could be attributed solely to selective inhibitory impairment.

Prefrontal serotonin depletion affects reversal learning but not attentional set shifting

Recently, we have shown that serotonin (5-HT) depletion from the prefrontal cortex (PFC) of the marmoset monkey impairs performance on a serial discrimination reversal (SDR) task, resulting in perseverative responding to the previously correct stimulus (Clarke et al., 2004). This pattern of impairment is just one example of inflexible responding seen after damage to the PFC, with performance on the SDR task being dependent on the integrity of the orbitofrontal cortex. However, the contribution of 5-HT to other forms of flexible responding, such as attentional set shifting, an ability dependent on lateral PFC (Dias et al., 1996a), is unknown. The present study addresses this issue by examining the effects of 5,7-dihydroxytryptamine-induced PFC 5-HT depletions on the ability to shift attention between two perceptual dimensions of a compound visual stimulus (extradimensional shift). Monkeys with selective PFC 5-HT lesions, despite being impaired in their ability to reverse a stimulus-reward association, were unimpaired in their ability to make an extradimensional shift when compared with sham-operated controls. These findings suggest that 5-HT is critical for flexible responding at the level of changing stimulus-reward contingencies but is not essential for the higher-order shifting of attentional set. Thus, psychological functions dependent on different loci within the PFC are differentially sensitive to serotonergic modulation, a finding of relevance to our understanding of cognitive inflexibility apparent in disorders such as obsessive-compulsive disorder and schizophrenia.

Inhibition of return in patients with obsessive-compulsive disorder

The present study is aimed at replicating and extending previous results by Nelson et al. [Psychiatry Res. 49 (1993) 183], who found decreased inhibition of return (IOR) in patients with obsessive-compulsive disorder (OCD). Thirty OCD patients, 14 psychiatric, and 14 healthy controls participated in a visual cueing experiment. The task required detection of a target stimulus at one of two possible locations. Prior to the target, an uninformative cue appeared at one of these two locations. The Stimulus Onset Asynchrony (SOA) between the cue and the target was systematically varied. We were especially interested in whether severity of OCD symptoms would be negatively correlated with inhibition for previously occupied locations. In accordance with prior research on healthy participants all groups displayed a comparable response pattern: facilitation at the short SOA condition and increasing IOR for the longer SOA conditions. Medication, comorbid depression, and OCD severity did not consistently moderate these effects.

Frontal lobe activation during object alternation acquisition

Object alternation (OA) tasks are increasingly used as probes of ventral prefrontal functioning in humans. In the most common variant of the OA task, subjects must deduce the task rule through trial-and-error learning. To examine the neural correlates of OA acquisition, the authors measured regional cerebral blood flow with positron emission tomography while subjects acquired an OA task, performed a sensorimotor control condition, or performed already learned and practiced OA. As expected, activations emerged in the ventral prefrontal cortex. However, activation of the presupplemental motor area was more closely associated with successful task performance. The authors suggest that areas beyond the ventral prefrontal cortex are critically involved in OA acquisition.

Selective cognitive deficits in obsessive-compulsive disorder compared to panic disorder with agoraphobia

OBJECTIVE

Visual-spatial and executive functions deficits have been reported in obsessive-compulsive disorder (OCD). We investigated their specificity comparing cognitive function in OCD, panic disorder with agoraphobia (PD/A) and controls by a comprehensive neuropsychological battery.

METHOD

Fifty-five subjects (25 OCD, 15 PD/A, 15 controls) without current depressive episode underwent structured clinical interview for DSM-IV, Yale-Brown Obsessive Compulsive Scale, Hamilton Anxiety Rating Scale, Hamilton Depression Rating Scale. Neuropsychological battery assessed: executive functions, visual discrimination, spatial memory and learning, verbal memory, general intellectual functioning.

RESULTS

OCD showed controlled fluency, visual-spatial construction, learning and memory deficits; PD/A spatial learning impairment. OCD was discriminated from PD/A and controls by three tests scores, predicting group membership for 76.4% of the cases.

CONCLUSION

Visual-constructive and controlled fluency deficits seem specific in OCD, while the spatial learning deficit, shared with PD patients, may not be disorder-specific, but anxiety-related. Results support the proposed ventral frontal-striatal circuit involvement in OCD.

Frontal lobe dysfunction in patients with chronic migraine: a clinical-neuropsychological study

Neuropsychological tests have demonstrated a frontal lobe dysfunction in several psychiatric and neurological disorders. Our purpose was to examine whether similar functional differences would be found in patients with chronic migraine. The Gambling Task (GT), the Tower of Hanoi-3 (TOH-3) and the Object Alternation Test (OAT) were administered to 23 female patients previously treated for chronic migraine and to 23 healthy women who were similar to the patients in age and educational level, and the mean test scores of the two groups were compared (Student's t and Pearson correlation coefficient). The patient group scored significantly higher than the controls on the TOH-3 and, especially, the OAT. In the patients, no significant relationship was found between the neuropsychological test scores and those for the Minnesota Multiple Personality Inventory (MMPI), the Spielberg State-Trait Anxiety Inventory (STAI), and the Beck Depression Inventory (BDI). In conclusion, the data suggest a relation between chronic headache and dorsolateral function (as tested by the TOH-3) and orbitofrontal function (as tested by the OAT). The decision-making function related to ventromedial prefrontal cortex (tested by the GT) did not show a statistically significant difference between patients and controls. These neuropsychological findings seem to be partly independent of the patient's psychological traits and psychiatric disorders.

Validation of Turkish and English Versions of the Schizotypal Personality Questionnaire-B

Abstract. We present normative data for a Turkish translation of the Schizotypal Personality Questionnaire-B (SPQ-B). The SPQ-B is a brief, self-report screening instrument developed by Raine and Benishay (1995) and is used to evaluate respondents for the presence of schizotypal personality features. We describe the internal consistency and test-retest reliability of the Turkish instrument and report intercorrelations among subfactors and total SPQ-B score. For comparison purposes, we present normative data for the SPQ-B (English version) from two studies examining schizotypy among nonclinical student samples in the United States. We report α coefficients and assess the convergent validity of the SPQ-B by examining the relationship between scores on the SPQ-B and performance on two existing measures of schizotypy and schizophrenic-spectrum personality disorders. Central tendency, distribution of scores, factor structure, and intercorrelations in both Turkish and US samples were similar, suggesting that our Turkish translation of the SPQ-B is a culturally valid instrument.