Neuroimaging in Obsessive-Compulsive Disorder

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.

Switch the itch: a naturalistic follow-up study on the neural correlates of cognitive flexibility in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a relatively common psychiatric disorder characterized by intrusive thoughts and behaviors that dominate daily living, like an itch patients cannot ignore. Deficits in executive functioning are common in OCD and are thought to be related to dysfunctional frontal-striatal systems. One of those executive functions is cognitive flexibility, defined as the ability to rapidly switch response strategies following changes in task-relevant information. The temporal stability of cognitive flexibility impairments in OCD has been incompletely investigated since previous studies have suggested both state and trait dependency. In this study, 16 OCD patients performed a functional magnetic resonance imaging version of a task-switching paradigm twice, intervened by a follow-up period of on average 6 months. Results show that functional abnormalities in the dorsal frontal-striatal circuit and anterior cingulate cortex at baseline normalized at follow-up. This change in the recruitment of task-related brain circuits correlated with change in disease severity. These results support the view that the imbalance between the dorsal and ventral frontal-striatal circuits is at least partly state-dependent, and is associated with a reduction in symptom severity.

Increased orbital frontal gray matter volume after cognitive behavioural therapy in paediatric obsessive compulsive disorder

OBJECTIVES

Identify differences in regional brain volume between medication-free pediatric OCD patients and controls and examine changes after cognitive behavioural therapy.

METHODS

We assessed 29 medication-free paediatric OCD patients (Age: M = 13.78 years; SD = 2.58; range 8.2-19.0) and 29 controls, matched on age and gender, with T1-weighted MR scans in a repeated measures, pre-post treatment design. Voxel based morphometry (VBM) following diffeomorphic anatomical registration through exponential lie algebra (DARTEL) was used to test voxel-wise for the effects of diagnosis and treatment on regional gray matter (GM) and white matter (WM) volumes.

RESULTS

After cognitive behavioural therapy, orbitofrontal GM and capsula externa WM increased in paediatric OCD relative to controls. In patients, changes in symptom severity (delta CY-BOCS) correlated positively with GM volume in the orbitofrontal cortex after treatment. Furthermore, before treatment, paediatric OCD patients, compared to the controls, showed larger GM volume in left frontal pole and left parietal cortex and larger WM volume in cingulum and corpus callosum.

CONCLUSIONS

Our findings underscore the involvement of the ventral frontal-striatal circuit in paediatric OCD and the plasticity of this circuit in response to the modulatory effects of CBT. The possible relation to brain development is discussed.

Cognitive inflexibility in obsessive-compulsive disorder and major depression is associated with distinct neural correlates

Obsessive-compulsive disorder (OCD) and major depressive disorder (MDD) are frequently co-morbid, and dysfunctional frontal-striatal circuits have been implicated in both disorders. Neurobiological distinctions between OCD and MDD are insufficiently clear, and comparative neuroimaging studies are extremely scarce. OCD and MDD may be characterized by cognitive rigidity at the phenotype level, and frontal-striatal brain circuits constitute the neural substrate of intact cognitive flexibility. In the present study, 18 non-medicated MDD-free patients with OCD, 19 non-medicated OCD-free patients with MDD, and 29 matched healthy controls underwent functional magnetic resonance imaging during performance of a self-paced letter/digit task switching paradigm. Results showed that both patient groups responded slower relative to controls during repeat events, but only in OCD patients slowing was associated with decreased error rates. During switching, patients with OCD showed increased activation of the putamen, anterior cingulate and insula, whereas MDD patients recruited inferior parietal cortex and precuneus to a lesser extent. Patients with OCD and MDD commonly failed to reveal anterior prefrontal cortex activation during switching. This study shows subtle behavioral abnormalities on a measure of cognitive flexibility in MDD and OCD, associated with differential frontal-striatal brain dysfunction in both disorders. These findings may add to the development of biological markers that more precisely characterize frequently co-morbid neuropsychiatric disorders such as OCD and MDD.

Limbic and motor circuits involved in symmetry behavior in Tourette's syndrome

OBJECTIVE

The need for symmetry and ordering objects related to a "just right"-feeling is a common symptom in Tourette's syndrome (TS) and resembles symmetry behavior in obsessive-compulsive disorder, but its pathophysiology is unknown. We used a symptom provocation paradigm to investigate the neural correlates of symmetry behavior in TS and hypothesized the involvement of frontal-striatal and limbic brain areas.

METHODS

Pictures of asymmetrically and symmetrically arranged objects were presented in randomized blocks (4 blocks of each condition) to 14 patients with TS and 10 matched healthy controls (HC). A H2 15O positron emission tomography scan was acquired during each stimulus block, resulting in 8 scans per subject. After each scan, state anxiety and symmetry behavior (the urge to rearrange objects) were measured using a visual analogue scale.

RESULTS

During the asymmetry condition, TS patients showed increased regional cerebral blood flow (rCBF) in the anterior cingulate cortex, supplementary motor area, and inferior frontal cortex, whereas HC showed increased rCBF in the visual cortex, primary motor cortex, and dorsal prefrontal cortex. Symmetry ratings during provocation correlated positively with orbitofrontal activation in the TS group and sensorimotor activation in the HC group, and negatively with dorsal prefrontal activity in HC.

CONCLUSIONS

Results suggest that both motor and limbic circuits are involved in symmetry behavior in TS. Motor activity may relate to an urge to move or perform tics, and limbic activation may indicate that asymmetry stimuli are salient for TS patients. In contrast, symmetry provocation in HC resulted in activation of brain regions implicated in sensorimotor function and cognitive control.

Common limbic and frontal-striatal disturbances in patients with obsessive compulsive disorder, panic disorder and hypochondriasis

BACKGROUND

Direct comparisons of brain function between obsessive compulsive disorder (OCD) and other anxiety or OCD spectrum disorders are rare. This study aimed to investigate the specificity of altered frontal-striatal and limbic activations during planning in OCD, a prototypical anxiety disorder (panic disorder) and a putative OCD spectrum disorder (hypochondriasis).

METHOD

The Tower of London task, a 'frontal-striatal' task, was used during functional magnetic resonance imaging measurements in 50 unmedicated patients, diagnosed with OCD (n=22), panic disorder (n=14) or hypochondriasis (n=14), and in 22 healthy subjects. Blood oxygen level-dependent (BOLD) signal changes were calculated for contrasts of interest (planning versus baseline and task load effects). Moreover, correlations between BOLD responses and both task performance and state anxiety were analysed.

RESULTS

Overall, patients showed a decreased recruitment of the precuneus, caudate nucleus, globus pallidus and thalamus, compared with healthy controls. There were no statistically significant differences in brain activation between the three patient groups. State anxiety was negatively correlated with dorsal frontal-striatal activation. Task performance was positively correlated with dorsal frontal-striatal recruitment and negatively correlated with limbic and ventral frontal-striatal recruitment. Multiple regression models showed that adequate task performance was best explained by independent contributions from dorsolateral prefrontal cortex (positive correlation) and amygdala (negative correlation), even after controlling for state anxiety.

CONCLUSIONS

Patients with OCD, panic disorder and hypochondriasis share similar alterations in frontal-striatal brain regions during a planning task, presumably partly related to increased limbic activation.

A critical review of the contribution of eye movement recordings to the neuropsychology of obsessive compulsive disorder

OBJECTIVE

Dysfunctions of saccadic and/or smooth pursuit eye movements have been proposed as markers of obsessive compulsive disorder (OCD), but experimental results are inconsistent. The aim of this paper was to review the literature on eye movement dysfunctions in OCD to assess whether or not saccades or smooth pursuit may be used to diagnose and characterize OCD.

METHOD

Literature was searched using PubMed, ISI Web of Knowledge, and PsycINFO databases for all studies reporting eye movements in adult patients suffering from OCD.

RESULTS

Thirty-three articles were found. As expected, eye movements of the patients with OCD were mostly assessed with simple oculomotor paradigms involving saccadic and/or smooth pursuit control. In contrast to patients with schizophrenia, however, patients with OCD only displayed rather unspecific deficits, namely slight smooth pursuit impairments and longer response latencies on antisaccade tasks. There was no relationship between these deficits and the severity of patients' symptoms. Interestingly, eye movements of the patients with OCD were almost never recorded during more complex cognitive tasks.

CONCLUSION

As in schizophrenia and autism, eye movement recordings during more complex tasks might help to better characterize the cognitive deficits associated with OCD. Such recordings may reveal specific OCD-related deficits that could be used as reliable diagnostic and/or classification tools.

Frontal-striatal abnormalities underlying behaviours in the compulsive-impulsive spectrum

In this paper, we tentatively bring together the psychiatric, neurological and addiction perspectives on the impulsive-compulsive spectrum of neuropsychiatric disorders, in order to understand the pathophysiology of impulse control disorders (ICDs) in Parkinson's disease. In an attempt to try to pool the various levels of information we will therefore focus on three disorders within the impulse-compulsive spectrum, i.e., obsessive-compulsive disorder (OCD), ICDs in Parkinson's disease, and cocaine seeking behaviour. Whereas there are large differences between these three domains, each with their own nomenclature, hypotheses and study results, they share the focus on an imbalance within and between the frontal-striatal circuits as underlying substrate for the behaviours. For each disorder, we summarize the results from recent studies in order to describe in which way alterations in the frontal-striatal circuits contribute to the phenotype. The phenomenological overlap between ICDs in Parkinson's disease, addiction and OCD needs further investigation, since better understanding of the overlapping and differentiating characteristics will contribute to our understanding of the pathophysiology of the disturbances and treatment alternatives.

Differential frontal-striatal and paralimbic activity during reversal learning in major depressive disorder and obsessive-compulsive disorder

BACKGROUND

Several lines of research suggest a disturbance of reversal learning (reward and punishment processing, and affective switching) in patients with major depressive disorder (MDD). Obsessive-compulsive disorder (OCD) is also characterized by abnormal reversal learning, and is often co-morbid with MDD. However, neurobiological distinctions between the disorders are unclear. Functional neuroimaging (activation) studies comparing MDD and OCD directly are lacking.

METHOD

Twenty non-medicated OCD-free patients with MDD, 20 non-medicated MDD-free patients with OCD, and 27 healthy controls performed a self-paced reversal learning task in an event-related design during functional magnetic resonance imaging (fMRI).

RESULTS

Compared with healthy controls, both MDD and OCD patients displayed prolonged mean reaction times (RTs) but normal accuracy. In MDD subjects, mean RTs were correlated with disease severity. Imaging results showed MDD-specific hyperactivity in the anterior insula during punishment processing and in the putamen during reward processing. Moreover, blood oxygen level-dependent (BOLD) responses in the dorsolateral prefrontal cortex (DLPFC) and the anterior PFC during affective switching showed a linear decrease across controls, MDD and OCD. Finally, the OCD group showed blunted responsiveness of the orbitofrontal (OFC)-striatal loop during reward, and in the OFC and anterior insula during affective switching.

CONCLUSIONS

This study shows frontal-striatal and (para)limbic functional abnormalities during reversal learning in MDD, in the context of generic psychomotor slowing. These data converge with currently influential models on the neuropathophysiology of MDD. Moreover, this study reports differential neural patterns in frontal-striatal and paralimbic structures on this task between MDD and OCD, confirming previous findings regarding the neural correlates of deficient reversal learning in OCD.

Paediatric obsessive-compulsive disorder, a neurodevelopmental disorder? Evidence from neuroimaging

OBJECTIVE

To present an overview of neuroimaging data on paediatric obsessive-compulsive disorder (OCD) and discuss implications for further research.

METHOD

Medline PsycINFO databases and reference lists were searched for relevant articles. All neuroimaging studies up to October 1, 2008 involving children and adolescents with obsessive-compulsive disorder were included.

RESULTS

Twenty-eight neuroimaging studies using various neuroimaging techniques (CT (2) MRI (15) MRS (8) and SPECT (2) fMRI (2) but no PET or DTI) including a total of 462 paediatric patients were identified. A number of findings indicate a dysfunction of the prefrontal-striatal-thalamic circuit with the involvement of other basal ganglia structures (putamen globus pallidus) and the thalamus in contrast to adult studies which report mainly involvement of the caudate nucleus and orbitofrontal cortex. Several findings point at an aberrant development of the brain in paediatric OCD, patients when compared with healthy controls.

CONCLUSION

Neuroimaging studies have contributed to our understanding of the neurobiological basis of paediatric OCD. This review provides an agenda for further theory driven research in particular aimed at identifying a critical window of abnormal maturation of prefrontal-striatal-thalamic and limbic circuitry in paediatric OCD patients.

Parkinson's disease-related disorders in the impulsive-compulsive spectrum

In Parkinson's disease (PD), there is increasing evidence for disorders in the impulsive-compulsive spectrum, related to the disease itself, to the pharmacological management of this disease or to both. These disorders comprise dopamine deficiency syndrome (with immediate reward seeking behaviour), dopamine dependency syndrome (with addictive behaviour), dopamine dysregulation syndrome (with both addictive behaviour and stereotyped behaviour) and impulse control disorders (such as pathological gambling, compulsive shopping, binge eating and hypersexuality). These disorders are especially seen in PD patients with young age of onset, higher doses of antiparkinsonian drugs, pre-existent or current depression, pre-existing recreational drug or alcohol use, and high novelty seeking personality traits.Dopamine is not only implicated in voluntary movement control but also plays a significant role in the brain's reward system and the modulation of behaviours. Therefore, most if not all drugnaïve PD patients will suffer dysphoria, leading to mild immediate reward seeking behaviour as a consequence of the striatal dopaminergic denervation. In some of these patients, during treatment, this may even lead to the intake of increasing quantities of levodopa, above those required to adequately treat motor parkinsonism, with all characteristics of a dopamine dependence syndrome. These patients may develop plastic changes in the striatal matrix leading to hyperkinesia, caused by extracellular striatal dopaminergic fluctuations due to pulsatile dopamine replacement therapy. As soon as these changes are also seen in the striatal striosomes, in the framework of a dopamine dysregulation syndrome, stereotyped behaviours (punding) may occur (supposedly due to dorsal versus ventral striatal overactivity). Finally, impulse control disorders are suggested as being pure adverse side-effects of dopamine replacement therapy. Obsessive-compulsive behaviour (caused by ventral to dorsal overactivity) so far has not been described in PD patients.Treatment of impulse control disorders is related to the underlying pathology. In the case of an intrinsic dopamine deficiency syndrome, treatment with dopamine replacement therapy, especially levodopa, will help. In the multifactorial (intrinsic and extrinsic) dopamine dependency and dysregulation syndromes, addictive behaviour might best be helped by psychosocial strategies, and punding by continuous dopaminergic receptor stimulation (or amantadine), hypothesized to reduce the plastic changes-induced hypersensitization. The extrinsic impulse control disorders might be best treated by reducing or replacing dopamine receptor agonists.

The major symptom dimensions of obsessive-compulsive disorder are mediated by partially distinct neural systems

Obsessive-compulsive disorder (OCD) is a clinically heterogeneous disorder characterized by multiple, temporally stable symptom dimensions. Preliminary functional neuroimaging studies suggest that these symptom dimensions may have distinct neural substrates. Whole-brain voxel-based morphometry was used to examine the common and distinct neuroanatomical (structural) substrates of the major symptom dimensions of OCD. First, we compared 55 medication-free patients with OCD and 50 age-matched healthy control subjects. Multiple regression analyses were then used to examine the relationship between global and regional grey matter (GM) and white matter (WM) volumes and symptom dimension scores within the patient group. OCD patients showed decreased GM volume in left lateral orbitofrontal (BA47), left inferior frontal (BA44/45), left dorsolateral prefrontal (BA9) and right medial prefrontal (BA10) cortices and decreased bilateral prefrontal WM volume. Scores on the 'symmetry/ordering' dimension were negatively correlated with 'global' GM and WM volumes. Scores on the 'contamination/washing' dimension were negatively correlated with 'regional' GM volume in bilateral caudate nucleus and WM volume in right parietal region. Scores on the 'harm/checking' dimension were negatively correlated with regional GM and WM volume in bilateral temporal lobes. Scores on the 'symmetry/ordering' dimension were negatively correlated with regional GM volume in right motor cortex, left insula and left parietal cortex and positively correlated with bilateral temporal GM and WM volume. The results remained significant after controlling for age, sex, educational level, overall illness severity, global WM and GM volumes and excluding patients with comorbid depression. The reported symptom dimension-specific GM and WM alterations support the hypothesis that OCD is an etiologically heterogeneous disorder, with both overlapping and distinct neural correlates across symptom dimensions. These results have clear implications for the current neuroanatomical model of OCD and call for a substantial revision of such model which takes into account the heterogeneity of the disorder.

Common and distinct neural correlates of obsessive-compulsive and related disorders

Obsessive-compulsive disorder (OCD) often co-occurs with other anxiety disorders and a number of other disorders of similar phenomenology known as the "OCD spectrum" disorders. Neurobiologically, it is unclear how all these disorders relate to each other. The picture is further complicated by the clinical heterogeneity of OCD itself. This article reviews the literature on the common and distinct neural correlates of OCD, its symptom dimensions, and other anxiety and OCD spectrum disorders with the hope of providing a conceptual and heuristic framework to help understand the relationship between these phenomena.

Applications of functional magnetic resonance imaging in psychiatry

While the use of MRI techniques has become a cornerstone of the neurology clinic, the application of such methods in psychiatry was rather limited until the advent of functional magnetic resonance imaging (fMRI). Over the past decade fMRI has superseded radionuclide-imaging techniques and blossomed into a widely used psychiatric research tool. This review focuses on the neurobiological findings from fMRI research in three less well-documented psychiatric disorders: attention deficit hyperactivity disorder (ADHD), depression, and obsessive-compulsive disorder (OCD). Although there was some disparity in early findings, greater standardization of image acquisition, analysis, and paradigms, and improved clinical classification are leading to a greater convergence of observations from different laboratories. fMRI is also beginning to realize its potential as an important mediator between genes and phenotypes, and may thus contribute to a better understanding of the pathophysiology of major neuropsychiatric diseases. The role of fMRI in the objective assessment of therapeutic intervention and early prediction of response to treatment is also discussed.