Obsessive-compulsive disorder following brain injury: a review

Defining repetitive behaviours in frontotemporal dementia

Repetitive behaviours are common manifestations of frontotemporal dementia (FTD). Patients with FTD exhibit various types of repetitive behaviours with unique behavioural and cognitive substrates, including compulsivity, lack of impulse control, stereotypy and hoarding. Other sources of repetitive behaviours, such as restrictive interests and insistence on sameness, may also be seen in FTD. Although repetitive behaviours are highly prevalent and potentially discriminatory in this population, their expression varies widely between patients, and the field lacks consensus about the classification of these behaviours. Terms used to describe repetitive behaviours in FTD are highly heterogeneous and may lack precise definitions. This lack of harmonization of the definitions for distinct forms of repetitive behaviour limits the ability to differentiate between pathological behaviours and impedes understanding of their underlying mechanisms. This review examines established definitions of well-characterized repetitive behaviours in other neuropsychiatric disorders and proposes operational definitions applicable to patients with FTD. Building on extant models of repetitive behaviours in non-human and lesion work and models of social behavioural changes in FTD, we describe the potential neurocognitive bases for the emergence of different types of repetitive behaviours in FTD and their potential perpetuation by a predisposition towards habit formation. Finally, examples of distinct therapeutic approaches for different forms of repetitive behaviours are highlighted, along with future directions to accurately classify, measure and treat these symptoms when they impair quality of life.

Genomics of Obsessive-Compulsive Disorder-Toward Personalized Medicine in the Era of Big Data

Pathogenesis of obsessive-compulsive disorder (OCD) mainly involves dysregulation of serotonergic neurotransmission, but a number of other factors are involved. Genetic underprints of OCD fall under the category of "common disease common variant hypothesis," that suggests that if a disease that is heritable is common in the population (a prevalence >1-5%), then the genetic contributors-specific variations in the genetic code-will also be common in the population. Therefore, the genetic contribution in OCD is believed to come from multiple genes simultaneously and it is considered a polygenic disorder. Genomics offers a number of advanced tools to determine causal relationship between the exposure and the outcome of interest. Particularly, methods such as polygenic risk score (PRS) or Mendelian Randomization (MR) enable investigation of new pathways involved in OCD pathogenesis. This premise is also facilitated by the existence of publicly available databases that include vast study samples. Examples include population-based studies such as UK Biobank, China Kadoorie Biobank, Qatar Biobank, All of US Program sponsored by National Institute of Health or Generations launched by Yale University, as well as disease-specific databases, that include patients with OCD and co-existing pathologies, with the following examples: Psychiatric Genomics Consortium (PGC), ENIGMA OCD, The International OCD Foundation Genetics Collaborative (IOCDF-GC) or OCD Collaborative Genetic Association Study. The aim of this review is to present a comprehensive overview of the available Big Data resources for the study of OCD pathogenesis in the context of genomics and demonstrate that OCD should be considered a disorder which requires the approaches offered by personalized medicine.

The effectiveness of cognitive behaviour therapy for reducing anxiety symptoms following traumatic brain injury: A meta-analysis and systematic review

BACKGROUND

Anxiety is a common neuropsychological sequela following traumatic brain injury (TBI). Cognitive Behaviour Therapy (CBT) is a recommended, first-line intervention for anxiety disorders in the non-TBI clinical population, however its effectiveness after TBI remains unclear and findings are inconsistent.

OBJECTIVE

There are no current meta-analyses exploring the efficacy of CBT as an intervention for anxiety symptoms following TBI, using controlled trials. The aim of the current study, therefore, was to systematically review and synthesize the evidence from controlled trials for the effectiveness of CBT for anxiety, specifically within the TBI population.

METHOD

Three electronic databases (Web of Science, PubMed and PsycInfo) were searched and a systematic review of intervention studies utilising CBT and anxiety related outcome measures in a TBI population was performed through searching three electronic databases. Studies were further evaluated for quality of evidence based on Reichow's (2011) quality appraisal tool. Baseline and outcome data were extracted from the 10 controlled trials that met the inclusion criteria, and effect sizes were calculated.

RESULTS

A random effects meta-analysis identified a small overall effect size (Cohen's d) of d = -0.26 (95%CI -0.41 to -0.11) of CBT interventions reducing anxiety symptoms following TBI.

CONCLUSIONS

This meta-analysis tentatively supports the view that CBT interventions may be effective in reducing anxiety symptoms in some patients following TBI, however the effect sizes are smaller than those reported for non-TBI clinical populations. Clinical implications and limitations of the current meta-analysis are discussed.

Efficacy and Harms of Pharmacological Interventions for Anxiety after Traumatic Brain Injury: Systematic Review

After a traumatic brain injury (TBI), many persons experience significant and debilitating problems with anxiety. The aim of this systematic review was to critically evaluate the evidence regarding efficacy of pharmacological interventions for anxiety after TBI. We reviewed studies published in English before July 2020 and included original research on pharmacological interventions for anxiety after TBI in adults ≥16 years of age. MEDLINE, PubMed, CINAHL, EMBASE, PsycINFO, and CENTRAL databases were searched, with additional searching of key journals, clinical trials registries, and international drug regulators. The primary outcomes of interest were reduction in symptoms of anxiety and occurrence of harms. The secondary outcomes of interest were changes in depression, cognition, quality of life, and participation. Data were summarized in a narrative synthesis, and evidence quality was assessed using the Cochrane Risk of Bias tool. Only a single non-peer-reviewed, randomized controlled trial of 19 male military service members with mild TBI met inclusion criteria. This study found no significant effect of citalopram on anxiety symptoms over a 12-week intervention. The trial was stopped early because of poor recruitment, and much of the study detail was not included in the report. The methodological quality of the study was difficult to assess because of the lack of detail. No recommendations could be drawn from this review. There is a critical need for adequately powered and controlled studies of pharmacological interventions for anxiety after TBI across all severities that examine side-effect profiles and consider issues of comorbidity and effects of long-term pharmacotherapy.

"Need to Know" or the Strong Urge to Find Names of Unique Entities in Acquired Obsessive-Compulsive Disorder

The two forms of obsessive-compulsive disorder (OCD), idiopathic and acquired, have been linked to abnormalities in the fronto-striato-thalamo-cortical circuitry, involving the orbitofrontal cortex, anterior cingulate cortex, thalamus, and striatum. Accumulating evidence indicates that damage to other brain regions (ie, temporal lobes) is also implicated in the pathogenesis of both types of OCD. In addition, some discrete OCD symptoms have received less attention because of their presumed low occurrence and difficultly of categorization. Among these, one intriguing and potentially severe type of obsessive thinking is the so-called "need to know" (NtK), which is a strong urge to access certain information, particularly proper names. In some patients, this monosymptomatic presentation may constitute the major feature of OCD. Here we report the cases of two patients who developed NtK obsessions with tenacious time-consuming, answer-seeking compulsions as the only or more disabling symptomatology in association with malignant tumors involving the right temporal lobe and connected fronto-subcortical circuits.

Association between cognitive impairments and obsessive-compulsive spectrum presentations following traumatic brain injury

This study examined the association between self-reported obsessive-compulsive spectrum symptomatology and cognitive performance in a sample of patients with traumatic brain injury (TBI). Twenty-four adults with a moderate-severe TBI accessing a community brain injury rehabilitation service were recruited. Age ranged between 19 and 69 years. Participants completed a battery of neuropsychological tasks assessing memory, executive functioning, and speed of information processing. Self-report questionnaires assessing obsessive-compulsive (OC) symptoms and obsessive-compulsive personality disorder (OCPD) traits were also completed. Correlational analyses revealed that deficits in cognitive flexibility were associated with greater self-reported OC symptomatology and severity. Greater OC symptom severity was significantly related to poorer performance on a visual memory task. Verbal memory and speed of information processing impairments were unrelated to OC symptoms. Performance on tasks of memory, executive functioning, and speed of information processing were not associated with OCPD traits. Overall, results indicate that greater OC symptomatology and severity were associated with specific neuropsychological functions (i.e., cognitive flexibility, visual memory). OCPD personality traits were unrelated to cognitive performance. Further research is needed to examine the potential causal relationship and longer-term interactions between cognitive sequelae and obsessive-compulsive spectrum presentations post-TBI.

Cerebral white matter volume changes in patients with obsessive-compulsive disorder: Voxel-based morphometry

AIMS

We carried out a voxel-based morphometry (VBM) study to evaluate cerebral white matter (WM) volume alteration in obsessive-compulsive disorder (OCD) and its correlation with the scores of the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS).

METHODS

Fourteen patients with OCD, who were diagnosed using the DSM-IV-TR, and 14 age-matched healthy controls participated. The high-resolution magnetic resonance imaging data were analyzed by voxel-based morphometry and Statistical Parametric Mapping 8.

RESULTS

There was no significant difference in the total intracranial volumes between OCD patients and healthy controls. However, patients with OCD showed significantly increased WM volumes in the right dorsolateral prefrontal cortex, middle frontal gyrus, precuneus, and inferior parietal lobule compared with healthy controls. In addition, the OCD patients showed a positive correlation between the WM volumes of the dorsolateral prefrontal cortex and Y-BOCS scores (r = 0.334, P = 0.03 and Pearson's correlation coefficient = 0.58) rating for the severity of OCD symptoms.

CONCLUSIONS

WM volume variations of the specific brain regions in patients with OCD will be helpful to understand the neural connectivity associated with a symptom of OCD. Furthermore, the findings would be valuable to aid the diagnostic accuracy of OCD in connection with morphometric magnetic resonance imaging analysis.

What do we know about obsessive-compulsive disorder following traumatic brain injury?

In addition to the well-known cognitive impairment following traumatic brain injury (TBI), neuropsychiatric sequelae are often reported as well. Although not the most common neuropsychiatric consequence of TBI, obsessive-compulsive disorder (OCD) has been associated with TBI. However, diagnosing new onset OCD secondary to TBI is complicated by the potential for cognitive impairment secondary to TBI masquerading as OCD. In particular, memory difficulties and executive dysfunction may be confused as representing obsessions and compulsions. Research in this area, which could guide clinical practice, remains limited. In addition to using Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) criteria, neuropsychological testing and collateral interviews may help clinicians when considering differential diagnoses in this complex area of neuropsychiatry.

Obsessive-compulsive disorder is associated with broad impairments in executive function: A meta-analysis

Obsessive-compulsive disorder (OCD) is a serious and often chronically disabling condition. The current dominant model of OCD focuses on abnormalities in prefrontal-striatal circuits that support executive function (EF). While there is growing evidence for EF impairments associated with OCD, results have been inconsistent, making the nature and magnitude of these impairments controversial. The current meta-analysis uses random-effects models to synthesize 110 previous studies that compared participants with OCD to healthy control participants on at least one neuropsychological measure of EF. The results indicate that individuals with OCD are impaired on tasks measuring most aspects of EF, consistent with broad impairment in EF. EF deficits were not explained by general motor slowness or depression. Effect sizes were largely stable across variation in demographic and clinical characteristics of samples, although medication use, age, and gender moderated some effects.

Obsessions appear after the removal a brain tumor in the right frontal lobe

A series of case reports and neuroimaging research points to the underlying neuropathological substrate for obsessive-compulsive disorder (OCD) and the underlying associations between OCD and areas of the frontal lobe. We report a patient wherein the onset of OCD occurred after resection of meningioma of the right frontal lobe and who was treated successfully with paroxetine hydrochloride. We suggest that the onset of secondary (organic) OCD is associated with the frontal lobe, and we propose that the origin of obsessions is located in the right frontal lobe.

Diagnosis and treatment of an obsessive-compulsive disorder following traumatic brain injury: a single case and review of the literature

A 27-year-old patient with traumatic brain injury and neuropsychiatric symptoms fitting the obsessive-compulsive disorder was investigated. Brain CT-scan revealed left temporal and bilateral fronto-basal parenchymal contusions. Main Outcome Measure was the Yale-Brown Obsessive Compulsive Scale at pre- and post-treatment and at 6 months follow-up. The combination of pharmacotherapy and psychotherapy resulted in lower intensity and frequency of symptoms. Our case illustrates the importance of a detailed diagnostic procedure in order to provide appropriate therapeutic interventions. Further studies are needed to guide the clinician in determining which patients are likely to benefit from a psychotherapeutic intervention in combination with pharmacotherapy.

Psychiatric outcome after severe cardio-respiratory failure treated with extracorporeal membrane oxygenation: a case-series

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is increasingly used to save patients with severe cardiopulmonary failure at high risk of dying, but the long-term psychiatric outcome of the treatment has not been studied.

METHODS

Twenty-eight adults who survived ECMO were subjected to psychiatric assessment 5 years after ECMO by means of interviews (MINI-Neuropsychiatric Interview and Montgomery-Åsberg Depression Rating Scale) and psychometrics [Neuroticism and social conformity (EPQ-N+L); General Health Questionnaire (GHQ), Hospital Anxiety Depression Scale; Aggression Questionnaire, Toronto Alexithymia Scale, and Giessener somatic symptom checklist (GBB)].

RESULTS

Fifteen patients (54%) suffered lifetime psychiatric disorders prior to ECMO. After ECMO, 11 subjects (39%) developed new psychiatric disorders, mostly organic mental (18%), obsessive-compulsive disorders (OCD) 15%, and/or post-traumatic stress disorders (PTSD) 11%. These 11 patients reported higher scores on Montgomery-Åsberg Depression Rating Scale (MADRS), GHQ, EPQ-N, and GBB. Disregarding the presence of psychiatric disorders at follow-up, ECMO patients reported high levels of distress, physical aggression, anger, and alexithymic traits.

CONCLUSIONS

Severe life-threatening cardiovascular or pulmonary failure with subsequent ECMO is associated with an increased prevalence of long-term psychiatric disorders and distress. Studies addressing the etiology and prevalence of psychiatric consequences after ECMO are needed.

Obsessive-compulsive disorder in chronic epilepsy

There is a long-recognized association between obsessive-compulsive disorder (OCD) and chronic epilepsy, most notably refractory temporal lobe epilepsy (TLE). The literature documents this association with case reports, patient series, and some larger controlled studies that reveal that almost a quarter of patients with TLE exhibit OCD features, which may go unrecognized. Obsession features with ordering, symmetry, exactness, handwashing, and religiosity occur more often in persons with right- or left-sided epileptic foci than in those with idiopathic generalized epilepsies or controls. Neurobiological and social factors suggest abnormalities of the frontal-thalamic-pallidal-striatal-anterior cingulate-frontal circuits stemming from the observation that certain diseases, damage, or surgery along these circuits may produce or, conversely, reduce OCD in TLE. This review explores the literature on case reports, case series, and larger retrospective controlled studies and looks at the associations of epilepsy with OCD. Contemporary speculation on the theoretical neurobiological underpinnings provides some basis on how and where to direct treatment. Invasive deep brain stimulation has triggered recent controversy on newer treatment modalities.

Contribution of subregions of human frontal cortex to novelty processing

Novelty processing was studied in patients with lesions centered in either OFC or lateral pFC (LPFC). An auditory novelty oddball ERP paradigm was applied with environmental sounds serving as task irrelevant novel stimuli. Lesions to the LPFC as well as the OFC resulted in a reduction of the frontal Novelty P3 response, supporting a key role of both frontal subdivisions in novelty processing. The posterior P3b to target sounds was unaffected in patients with frontal lobe lesions in either location, indicating intact posterior cortical target detection mechanisms. LPFC patients displayed an enhanced sustained negative slow wave (NSW) to novel sounds not observed in OFC patients, indicating prolonged resource allocation to task-irrelevant stimuli after LPFC damage. Both patient groups displayed an enhanced NSW to targets relative to controls. However, there was no difference in behavior between patients and controls suggesting that the enhanced NSW to targets may index an increased resource allocation to response requirements enabling comparable performance in the frontal lesioned patients. The current findings indicate that the LPFC and OFC have partly shared and partly differential contributions to the cognitive subcomponents of novelty processing.

Aberrant ventral striatal responses during incentive processing in unmedicated patients with obsessive-compulsive disorder

OBJECTIVE

Obsessive-compulsive disorder (OCD) is characterized by the dysfunction of control and reward mechanisms. However, only few neuroimaging studies of OCD have examined the reward processing. We examined the neural responses during incentive processing in OCD.

METHOD

  Twenty unmedicated patients with OCD and 20 age-, sex-, and IQ-matched healthy controls underwent functional magnetic resonance imaging while performing a modified monetary incentive delay task.

RESULTS

Compared with controls, patients with OCD showed increased ventral striatal activation in the no-loss minus loss outcome contrast and a significant positive correlation between the ventral striatal activation and compulsion symptom severity. In addition, patients with OCD showed increased activations in the frontostriatal regions in the gain minus no-gain outcomes contrast. During loss anticipation, patients with OCD showed less activations in the lateral prefrontal and inferior parietal cortices. However, during gain anticipation, patients with OCD and healthy controls did not differ in the ventral striatal activation.

CONCLUSION

These findings provide neural evidence for altered incentive processing in unmedicated patients with OCD, suggesting an elevated sensitivity to negatively affect stimuli as well as dysfunction of the ventral striatum.

Microstructural brain abnormalities in patients with obsessive-compulsive disorder: diffusion-tensor MR imaging study at 3.0 T

PURPOSE

To use diffusion-tensor (DT) magnetic resonance (MR) imaging to explore the integrity and connectivity of brain white matter in patients with obsessive-compulsive disorder (OCD) and to correlate DT parameters with clinical measures.

MATERIALS AND METHODS

This study was approved by the local ethical committee, and written informed consent was obtained from all participants. DT imaging was performed by using a 3.0-T MR imager in 23 patients with OCD and 23 healthy control subjects matched for age, sex, education level, and handedness. By using voxel-based analysis, fractional anisotropy (FA) and axial and radial diffusivities were compared between patients and control subjects with a two-sample t test and were tested for correlation with symptom severity, as measured by using the Yale-Brown Obsessive-Compulsive Scale and obsessive-compulsive subscale scores, and with illness duration, as measured by using simple regression in statistical parametric mapping program.

RESULTS

Compared with control subjects, OCD patients demonstrated significantly increased FA in the genu and body of corpus callosum and white matter of right superior frontal gyrus and corpus callosum; no areas of significantly decreased FA were found. For areas of increased FA, axial diffusivity was higher than that in control subjects, while radial diffusivity was not significantly different. The FA values in the white matter of left middle temporal gyrus in OCD patients correlated positively with clinical measures (r = 0.542, P < .001).

CONCLUSION

OCD is associated with axonal microstructural abnormalities within the white matter, which may indicate impaired axonal integrity and increased connectivity. The positive correlation between DT abnormalities and symptom severity suggests that DT imaging may be of clinical value in measuring and following disability in OCD patients.

Increased self-report of obsessive-compulsive behaviors among hemodialysis patients: a case-control study

BACKGROUND

Patients with end-stage renal insufficiency undergoing hemodialysis show important psychiatric morbidity, particularly increased depression and anxiety. Obsessive-compulsive symptoms, however, are much less frequently investigated. The purpose of the present study was thus to assess obsessive-compulsive symptoms in hemodialysis patients.

METHOD

Patients treated at an outpatient hospital hemodialysis unit (July 2007) were compared with controls on scores on the Maudsley Obsessional-Compulsive Inventory (MOCI) and its checking, cleaning, slowness, and doubting components as well as on measures of emotional (Beck Depression Inventory-Fast Screen), anxiety (Beck Anxiety Inventory), and cognitive (Trail Making Test) status. Student t tests, analyses of covariance, or nonparametric tests were used. Correlations were applied between behavioral outcomes and demographic, clinical, and laboratory data of patients.

RESULTS

Patients showed more obsessive traits than controls on the MOCI total score (P < .001) and on the checking, cleaning, and doubting subscales. Significant differences between groups occurred also in Beck Depression and Anxiety Inventories (P ≤ .001). The MOCI total score did not correlate with marital status, education level, duration of hemodialysis, or the other psychological instrument scores in patients. By contrast, the MOCI total score was associated with the level of creatinine, and it showed an inverse correlation with the urea reduction ratio in patients (P < .05).

CONCLUSIONS

Obsessive-compulsive symptoms may constitute an important aspect of the psychiatric profile of patients undergoing hemodialysis. Potential interpretation involves disease- and treatment-associated factors or adaptive responses to emergence of otherwise uncontrollable stress.

Late-onset obsessive compulsive disorder associated with possible gliomatosis cerebri

Onset of obsessive-compulsive disorder (OCD) after the age of 50 years is rare, and should alert the physician to possible "organic" causes of OCD. These include infections, degenerative disorders, brain injury and cerebrovascular lesions, principally involving the frontal lobes and basal ganglia. The current patient had obsessive images, anxiety, auditory hallucinations and seizures following (possible) gliomatosis cerebri, with onset around 69 years of age. The atypical presentation, lesions involving the cortical-basal ganglia-thalamic-cortical circuit and the association with neurological signs/symptoms, was characteristic. However, late-onset OCD has not been commonly reported with diffuse lesions, and the association with gliomatosis cerebri is not known. This patient's case illustrates the need for careful screening of older patients with recently acquired OCD, and for further systematic study of OCD in the broad range of neuropsychiatric disorders affecting the elderly.

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.

Ruptured intracranial dermoid cyst presenting with neuropsychiatric symptoms: a case report

Psychiatric symptoms associated with frontal lobe unruptured or ruptured intracranial dermoid cysts are rarely described in the medical literature. The case of a 58-year-old man with a chronic history of anxiety, major depression, and obsessive compulsive disorder who presented with new onset auditory and visual phenomena is described. This case illustrates the need to include an underlying brain tumor in the differential diagnosis when encountering new onset auditory and visual phenomena in patients with chronic mood and/or anxiety disorders.

A comparative study of obsessive-compulsive disorder in Costa Rica and the United States

This study compares the presentation and expression of obsessive-compulsive symptoms between a Latin-American and North American sample. In Costa Rica (CR) and the United States (US), respectively, 26 and 52 affected individuals with early-onset obsessive-compulsive disorder (OCD) were recruited. The Yale Brown Obsessive Compulsive Scale (YBOCS), a semi-structured psychiatric interview, and self-report questionnaires were administered. Age of onset and the distribution of OCD across men and women were similar across groups. Both CR and US participants reported obsessions and compulsions, with similar frequencies of symptoms, and contamination, symmetry, and hoarding as the most common symptom subtypes. The US sample had higher YBOCS total severity scores than the Costa Rican group. Similarly, there were significant ethnicity effects for YBOCS compulsion [F(1, 70)=17.88, P<.001] and obsession severity [F(1, 70)=8.78, P<.001], with Caucasians having higher scores than Costa Ricans on both subscales. Comorbidity rates were higher for US Caucasians than Costa Ricans for all disorders; differences were significant for mood disorders [64.7% versus 34.6%], alcohol use [21.3% versus 3.8%], cannabis use disorders [19.1% versus 0%], and other substance use disorders [39.4% versus 0%]. Regression analyses revealed that ethnicity, trait anxiety, and proband status were the only significant predictors of total YBOCS severity. Findings suggest that the core phenotype of OCD is the same in both CR and the US, and perhaps biologically driven. However some features of OCD, such as impairment, may be culturally influenced, leading to differences in prevalence rates and treatment utilization.

What every psychiatrist should know about PANDAS: a review

The term Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcus infections (PANDAS) was coined by Swedo et al. in 1998 to describe a subset of childhood obsessive-compulsive disorders (OCD) and tic disorders triggered by group-A beta-hemolytic Streptococcus pyogenes infection. Like adult OCD, PANDAS is associated with basal ganglia dysfunction. Other putative pathogenetic mechanisms of PANDAS include molecular mimicry and autoimmune-mediated altered neuronal signaling, involving calcium-calmodulin dependent protein (CaM) kinase II activity. Nonetheless the contrasting results from numerous studies provide no consensus on whether PANDAS should be considered as a specific nosological entity or simply a useful research framework. Herein we discuss available data that could provide insight into pathophysiology of adult OCD, or might explain cases of treatment-resistance. We also review the latest research findings on diagnostic and treatment.

In vivo PET study of 5HT(2A) serotonin and D(2) dopamine dysfunction in drug-naive obsessive-compulsive disorder

There are several lines of evidence, the majority indirect, suggesting that changes in serotonergic or dopaminergic neurotransmission may contribute to the pathogenesis of obsessive-compulsive disorder (OCD). We evaluated the co-occurrence of serotonergic and dopaminergic dysfunctions in OCD subjects, all drug-naive, with no co-morbidity and homogeneous for symptoms. Each subject underwent two positron emission tomography (PET) scans to measure in vivo both serotonin (5-HT(2A)) and dopamine (D(2)) receptor distribution. For this, we used [11C]MDL and [11C]Raclopride, highly selective antagonists of 5-HT(2A) and D(2) receptors, respectively. The comparison with a control group was carried out using both voxel-wise (SPM2) and regions of interest (ROI) approaches. There was a significant reduction of 5-HT(2A) receptor availability in frontal polar, dorsolateral, and medial frontal cortex, as well as in parietal and temporal associative cortex of OCD patients. We also found a significant correlation between 5-HT(2A) receptor availability in orbitofrontal and dorsolateral frontal cortex and clinical severity, suggesting a specific role for serotonin in determining the OCD symptoms. There was also a significant reduction of [11C]Raclopride uptake in the whole striatum, particularly in the ventral portion, possibly reflecting endogenous dopaminergic hyperactivity. The co-existence of serotonergic and dopaminergic dysfunction in the same homogeneous group of drug-naive OCD patients provides in vivo evidence for the complex molecular mechanisms of OCD, and represents the basis for further studies on the effect of therapeutic agents with specific modulatory effects on these neurotransmission systems.

Morphometric magnetic resonance imaging in psychiatry

Although advances in the clinical criteria of various axis I psychiatric disorders are continually being made, there is still considerable overlap in the clinical features, and diagnosis is often challenging. As a result, there has been substantial interest in using morphometric magnetic resonance imaging to better characterize these diseases and inform diagnosis. Region of interest and voxel-based morphometry studies are reviewed herein to examine the extent to which these goals are being met across various psychiatric disorders. It is concluded based on the studies reviewed that specific patterns of regional loss, although present in certain axis I disorders, are not, as yet, diagnostically useful. However, advances in outcome and treatment monitoring show considerably more promise for rapid application in psychiatry.

The spectrum of recurrent thoughts and behaviors in frontotemporal dementia

This article describes the spectrum of recurrent thoughts and behaviors that can result from frontotemporal dementia (FTD) and its variants. Although repetitive behaviors can result from a range of brain disorders, FTD is the most common neurologic cause of new-onset recurrent thoughts and behaviors in middle or late life. Patients with FTD can manifest typical or bizarre compulsions, hoarding, verbal and motor stereotypies and complex tics; self-injurious acts, perseverations; and fixed, obsessional thoughts. The frequency and variability of these repetitive behaviors suggest a common disturbance of orbitofrontal-basal ganglia circuits involved in response inhibition. The amelioration of these recurrent events with the administration of serotonin selective reuptake inhibitors further suggests a serotonergic deficit.

A psychological and neuroanatomical model of obsessive-compulsive disorder

Imaging, surgical, and lesion studies suggest that the prefrontal cortex (orbitofrontal and anterior cingulate cortexes), basal ganglia, and thalamus are involved in the pathogenesis of obsessive-compulsive disorder (OCD). On the basis of these findings several models of OCD have been developed, but have had difficulty fully integrating the psychological and neuroanatomical findings of OCD. Recent research in the field of cognitive neuroscience on the normal function of these brain areas demonstrates the role of the orbitofrontal cortex in reward, the anterior cingulate cortex in error detection, the basal ganglia in affecting the threshold for activation of motor and behavioral programs, and the prefrontal cortex in storing memories of behavioral sequences (called "structured event complexes" or SECs). The authors propose that the initiation of these SECs can be accompanied by anxiety that is relieved with completion of the SEC, and that a deficit in this process could be responsible for many of the symptoms of OCD. Specifically, the anxiety can form the basis of an obsession, and a compulsion can be an attempt to receive relief from the anxiety by repeating parts of, or an entire, SEC. The authors discuss empiric support for, and specific experimental predictions of, this model. The authors believe that this model explains the specific symptoms, and integrates the psychology and neuroanatomy of OCD better than previous models.

White matter abnormalities in drug-naïve patients with obsessive-compulsive disorder: a diffusion tensor study before and after citalopram treatment

OBJECTIVE

The aim was to investigate the white matter abnormalities of drug-naïve patients with obsessive-compulsive disorder (OCD) using diffusion tensor-imaging and the white matter changes in the patients after pharmacotherapy.

METHOD

Thirteen drug-naïve OCD patients and 13 age- and sex-matched healthy comparison subjects were examined using diffusion tensor-imaging and structural magnetic resonance imaging. Measurements were made in OCD patients before and after 12 weeks of citalopram treatment.

RESULTS

Compared with controls, the drug-naïve OCD patients showed significant increases in fractional anisotropy (FA) in the corpus callosum, the internal capsule and white matter in the area superolateral to the right caudate. The increases in FA were mostly no longer observed in patients after 12 weeks of treatment compared with controls.

CONCLUSION

Our findings suggest that white matter alterations are associated with the pathophysiology of OCD, and the abnormalities may be partly reversible with pharmacotherapy.