Orbital frontal cortex in treatment-naïve pediatric obsessive-compulsive disorder

Transcranial direct current stimulation in obsessive-compulsive disorder: an update in electric field modeling and investigations for optimal electrode montage

Introduction: Transcranial Direct Current Stimulation (tDCS) is a non-invasive brain stimulation intervention that has been investigated for several psychiatric disorders, including Obsessive-Compulsive Disorder (OCD). As there are several candidate brain regions for targeting OCD relevant networks, clinical studies using tDCS have considerably varied in terms of the electrode montages used. Computer modeling of electric field currents induced by tDCS can help guiding the research of relevant targets for OCD. In this review, the authors used this tool to investigate targeted brain areas from previous studies of tDCS in OCD. Areas covered: A literature search for articles with the keywords 'tDCS', 'Transcranial Direct Current Stimulation' and 'Obsessive Compulsive Disorder' was conducted to identify relevant publications. For comparing different electrode montages, electric field (EF) models were performed using high-resolution brain scan templates. Authors found 13 studies mostly showing an improvement in OCD symptoms. The electrode montages varied considerably between studies. Nonetheless, two main patterns of EFs could be identified: 'focal montages', with EFs concentrated in the prefrontal cortex, and 'diffuse montages', with widespread EFs over cortical areas. Expert opinion: Electric field simulation can guide future clinical trials in psychiatry, using personalized tDCS montages with distinct electrode positioning according to clusters of symptoms.

An interrogation of cognitive findings in pediatric obsessive-compulsive and related disorders

Current findings in the field of psychology have led to increased interest and a new conceptualization of disorders characterized by repetitive behaviors, namely the obsessive compulsive and related disorders (OCRDs). Scant research, however, has sought to collect and categorize the extant research on pediatric OCRDs. Particularly, no adequate review of the pediatric cognitive literature existed until now, despite the clear implication of abnormalities in neuroanatomical structures and cognitive functioning in adult samples. While evidence for cognitive dysfunction in pediatric samples is presented, this paper also suggests that differences in cognitive dysfunction may indeed exist between adults and youth with OCRDs. Specifically, those irregularities present in said youth at varying developmental stages may impact the origination and maintenance of OCRDs across time. Finally, this paper seeks to formulate potential future goals for the research field, particularly through transdiagnostic approaches to processes linked with symptom presentations. This is of particular importance as an improved understanding of the interaction of cognitive function and growth is key to further comprehension of the OCRDs.

White matter structural alterations in pediatric obsessive-compulsive disorder: relation to symptom dimensions

The aims of this study were to identify gray matter (GM) and white matter (WM) volume abnormalities in pediatric obsessive-compulsive patients, to examine their relationship between these abnormalities and the severity of disorder, and to explore whether they could be explained by the different symptom dimensions.

METHODS

62 child and adolescent OCD patients (11-18years old) and 46 healthy subjects of the same gender and similar age and estimated intellectual quotient were assessed by means of psychopathological scales and magnetic resonance imaging (MRI). Axial three-dimensional T1-weighted images were obtained in a 3T scanner and analyzed using optimized voxel-based morphometry (VBM).

RESULTS

Compared with healthy controls, OCD patients showed lower white matter (WM) volume in the left dorsolateral and cingulate regions involving the superior and middle frontal gyri and anterior cingulate gyrus (t=4.35, p=0.049 FWE (family wise error)-corrected). There was no significant correlation between WM and the severity of obsessive-compulsive symptomatology. There were no regions with lower gray matter (GM) volume in OCD patients than in controls. Compared with healthy controls, only the "harm/checking" OCD dimension showed a cluster with a near significant decrease in WM volume in the right superior temporal gyrus extending into the insula (t=5.61, p=.056 FWE-corrected).

CONCLUSION

The evidence suggests that abnormalities in the dorsolateral prefrontal cortex, anterior cingulate cortex, temporal and limbic regions play a central role in the pathophysiology of OCD. Moreover, regional brain volumes in OCD may vary depending on specific OCD symptom dimensions, indicating the clinical heterogeneity of the condition.

A longitudinal VBM study in paediatric obsessive-compulsive disorder at 2-year follow-up after cognitive behavioural therapy

OBJECTIVES

To identify neurodevelopmental differences in regional brain volume between medication-free paediatric obsessive-compulsive disorder (OCD) patients and controls at 2-year follow-up after cognitive behavioural therapy.

METHODS

We assessed 17 medication-free paediatric OCD patients (mean age 13.8 years; SD = 2.8; range 8.2-19.0) and 20 controls, matched on age and gender, with T1-weighted MR scans in a repeated measures design at three time points with intervals of 6 months and 2 years. Voxel based morphometry (VBM) was used to test whole brain voxel-wise for the effects of diagnosis and time on regional grey matter (GM) and white matter volumes.

RESULTS

GM volume of the orbitofrontal cortex showed a group × time interaction effect, driven by an increase of GM volume over the whole time period in OCD patients and a decrease in controls. When splitting the groups in two age groups (8-12 and 13-19 years) this interaction effect was only seen in the youngest age group.

CONCLUSIONS

Neuroimaging findings in paediatric OCD after 6 months of CBT in the GM volume of the orbital frontal cortex are still present at 2-year follow-up.

Widespread decreased grey and white matter in paediatric obsessive-compulsive disorder (OCD): a voxel-based morphometric MRI study

Obsessive-compulsive disorder (OCD) is a chronic, relapsing anxiety disorder. To date, neuroimaging investigations of OCD have been variable and few studies have examined paediatric populations. Eight children with OCD and 12 typically developing children matched for age, gender, handedness and performance IQ underwent a high resolution T1-weighted structural magnetic resonance imaging (MRI) scan. A voxel-based morphometry (VBM) protocol (using DARTEL) compared the brains of the paediatric OCD children with those of typically developing children. Overall, children with OCD demonstrated significantly lower intra-cranial volume (ICV) and grey- and white-matter volumes. ICV was significantly reduced (∼9%) in the OCD group compared with the typically developing group. The VBM analysis demonstrated lower volumes in widespread grey matter in bilateral frontal, cingulate, temporal-parietal, occipital-frontal and right precuneus regions for OCD. Lower white matter volume was found bilaterally in the cingulate and occipital cortex, right frontal and parietal and left temporal regions, and the corpus callosum. In summary, this study provides further evidence of brain dysmorphology in paediatric OCD patients. In addition to fronto-striatal-thalamic neural networks, abnormalities in other brain regions, such as the parietal lobe and corpus callosum, were demonstrated. These brain regions may play an additional role in the pathophysiology of OCD.

Glutamate system genes and brain volume alterations in pediatric obsessive-compulsive disorder: a preliminary study

Obsessive-compulsive disorder (OCD) has been associated with regional volumetric brain abnormalities, which provide promising intermediate phenotypes of the disorder. In this study, volumes of brain regions selected for a priori evidence of association with OCD (orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), thalamus, caudate, putamen, globus pallidus and pituitary) were measured using structural magnetic resonance imaging (MRI) in 20 psychotropic-naïve pediatric OCD patients. We examined the association between these regional brain volumes and a total of 519 single nucleotide polymorphisms (SNPs) from nine glutamatergic candidate genes (DLGAP1, DLGAP2, DLGAP3, GRIN2B, SLC1A1, GRIK2, GRIK3, SLITRK1 and SLITRK5). These genes were selected based on either previous reported association with OCD in humans or evidence from animal models of OCD. After correcting for multiple comparisons by permutation testing, no SNP remained significantly associated with volumetric changes. The strongest trend toward association was identified between two SNPs in DLGAP2 (rs6558484 and rs7014992) and OFC white matter volume. Our other top ranked association findings were with ACC, OFC and thalamus. These preliminary results suggest that sequence variants in glutamate candidate genes may be associated with structural neuroimaging phenotypes of OCD.

Comprehensive evaluation of cortical structure abnormalities in drug-naïve, adult patients with obsessive-compulsive disorder: a surface-based morphometry study

The study objective was to comprehensively evaluate drug-naïve, adult patients with Obsessive Compulsive Disorder (OCD) for cortical structure abnormalities in comparison with healthy controls. In this cross-sectional study of case-control design, Magnetic Resonance Imaging (1-mm) was performed in drug-naïve OCD patients (N = 50) & age- sex-, education- and handedness-matched healthy controls (N = 40). We examined cortical volume, thickness, surface area & local Gyrification Index (LGI) through a completely automated surface-based morphometric analysis using FreeSurfer software. OCD symptoms and insight were assessed using Yale-Brown Obsessive Compulsive Symptom (Y-BOCS) check-list and severity scale. Illness severity was assessed using Clinical Global Impression Severity (CGI-S) Scale. OCD patients had significantly deficient volume, thickness and surface area of right anterior cingulate gyrus (ACG). Right lingual gyrus surface area was found to be significantly decreased in patients. Y-BOCS obsession score had significant negative correlation with left frontal pole volume. Y-BOCS compulsion score had significant negative correlations with right ACG volume and surface area and right lateral orbitofrontal cortex LGI. CGI-Severity score had significant negative correlations with right lingual gyrus volume, thickness and surface area as well as right lateral orbitofrontal area. Y-BOCS insight score showed a significant negative correlation with LGI of left medial OFC and left rostral ACG. Identification of novel deficits involving occipital brain regions and first-time observations of relevant correlations between various illness characteristics and cortical measures in OCD patients supports a network involving anterior cingulate, orbitofrontal and occipital brain regions in the pathogenesis of OCD.

Genetics of pediatric anxiety disorders

This article reviews the familiality, linkage, candidate gene, and genomewide association studies of obsessive-compulsive disorder, panic disorder, posttraumatic stress disorder, and other anxiety disorders (ie, generalized anxiety disorder, separation anxiety disorder, social phobia, and specific phobia). Studies involving children and adolescents are highlighted. Clinical and research implications are discussed.

A review of obsessive-compulsive disorder in children and adolescents

This article is a review of recent literature on obsessive-compulsive disorder in the pediatric population. Areas covered include: a brief historical perspective, clinical presentation in relation to symptoms found in different age groups, epidemiology, psychiatric comorbidity, etiology (with regards to genetics, neuroimaging, and familial factors), clinical course and prognosis, and treatment, with special emphasis on individual and family-based cognitive-behavioral therapy and psychopharmacology.

Do defense styles of ego relate to volumes of orbito-frontal cortex in patients with obsessive-compulsive disorder?

OBJECTIVE

Although the importance of orbito-frontal cortex (OFC) is established in the pathogenesis of obsessive compulsive disorder (OCD), no study have evaluated its relation to the traditional psychodynamic perspective. In the present study, we aimed to evaluate the relationship between the defense styles consisting of mature, immature and neurotic defenses and OFC volumes of patients with OCD.

METHODS

Subjects were selected among those of our previous study, and so eighteen patients with OCD and same number of healthy controls were took into the study. The patients and controls had underwent magnetic resonance imaging (MRI). In addition, the Defense Style Questionnaire-40 was administered to obtain defense styles of patients and controls.

RESULTS

No significant relationship was found between the right OFC volumes of both the patient and control groups and their scores of mature, neurotic, or immature defense mechanisms. As for the left OFC volumes, the only significant relationship for the scores of immature defense mechanism was found in the patient group.

CONCLUSION

The results of the present study indicated that there was no significant relationship between OFC volumes of the patient group and their scores of mature, neurotic, or immature defense mechanisms, except a significant relation with the scores of immature defense mechanisms.

Serotonin transporter gene polymorphism implicates reduced orbito-frontal cortex in obsessive-compulsive disorder

Although a number of magnetic resonance imaging (MRI) and genetic studies have been performed on obsessive-compulsive disorder (OCD), only limited studies in which genetic and neuroanatomical variables are evaluated concurrently have been performed. Therefore, the aim of our present study is (to understand) better understanding how genetic variation in the promoter region of the 5-HTT gene (5-HTTLPR) is associated with key brain structures in OCD, orbito-frontal cortex (OFC), thalamus and anterior cingulate. 5-HTT genotypes (SS, SL, LL) were determined for 40 patients with OCD and the same number of healthy controls. MRI-derived volumes of the OFC, thalamus, and anterior cingulate were determined by reliable tracing techniques. Volumetric measurements were made with T1-weighted coronal MRI images, with 1.5-mm-thick slices, at 1.5T, and were done blindly. In comparison with controls, OCD patients demonstrated volumes reduction in OFC, increased volumes of thalamus and total white matter volumes, but no difference in total brain volume, total gray matter volumes and anterior cingulate volumes. No significant difference was observed in allelic frequencies between the patients and controls. The stronger effects of 5-HTT polymorphism on brain morphology in OCD than those in controls were determined in the both OFC and thalamus. On the other hand, for the OCD patients, ANCOVA revealed a significant main effect of genotype for both the OFC and thalamus and a significant genotype-by-side interaction for the OFC, demonstrating that the short variants had a smaller right OFC than the long variants. In conclusion, we found a significant genotype-diagnosis interaction effects on key brain structures, with a stronger effects of 5-HTT polymorphism in OFC and thalamus of OCD patients, whereas no morphological changes related to the polymorphism were found in normal individuals.

Is there evidence of brain white-matter abnormalities in obsessive-compulsive disorder?: a narrative review

OBJECTIVE

Although several studies have confirmed the occurrence of gray-matter abnormalities in obsessive-compulsive disorder (OCD), the literature on white matter in OCD is more limited. In this study, we reviewed the role of white-matter abnormalities in the pathophysiology of OCD.

METHOD

We reviewed the PubMed studies investigating white-matter integrity in patients with OCD between 1980 and 2010.

RESULTS

Case studies of patients who developed obsessive-compulsive symptoms secondary to multiple sclerosis, cerebrovascular diseases, and paraneoplastic leucoencephalopathy and controlled studies of patients with OCD examined with neuroimaging techniques (eg, structural, diffusion, and spectroscopic magnetic resonance imaging) were all consistent with the existence of abnormalities in specific white-matter tracts (eg, internal capsule, cingulate bundle, and corpus callosum) of individuals with OCD.

CONCLUSIONS

Our review emphasizes that the reported white-matter alterations in OCD complement the broader gray-matter abnormalities identified and may well suggest that OCD is associated with large-scale disruption in brain systems or networks, as opposed to being a consequence of disturbances in isolated brain regions.

A review of obsessive-compulsive disorder in children and adolescents

This article is a review of recent literature on obsessive-compulsive disorder in the pediatric population. Areas covered include: a brief historical perspective, clinical presentation in relation to symptoms found in different age groups, epidemiology, psychiatric comorbidity, etiology (with regards to genetics, neuroimaging, and familial factors), clinical course and prognosis, and treatment, with special emphasis on individual and family-based cognitive-behavioral therapy and psychopharmacology.