Hypofunctioning of sensory gating mechanisms in patients with obsessive-compulsive disorder

Neural correlates of trait anxiety in sensory processing and distractor filtering

Evidence suggests that trait anxiety relates to cognitive processing and behavior. However, the relationships between trait anxiety and sensory processing, goal-directed performance and sensorimotor function are unclear, particularly in a multimodal context. This study used electroencephalography to evaluate whether trait anxiety influenced visual and tactile event-related potentials (ERPs), as well as behavioral distractor cost, in a bimodal sensorimotor task. Twenty-nine healthy young adults completed the State-Trait Anxiety Inventory. Participants were directed to focus on either tactile or visual stimuli while disregarding the other modality, responding to target stimulus amplitude with a proportional grip. Previous research suggests that somatosensory N70 and visual P2 ERPs serve as markers of attentional relevance, with attention also impacting the visual P3 ERP. It was hypothesized that trait anxiety would modulate the ERPs susceptible to attentional modulation (tactile N70, visual P2 and P3) and not affect behavioral performance. Trait anxiety showed a large, significant interaction with attention for visual P3 latency in response to unimodal visual stimuli, with a positive relationship between P3 latencies and trait anxiety when attending toward the stimulus and negative when attending away. A large, positive main effect of trait anxiety on visual N1 amplitude for bimodal stimuli was also detected. As predicted, trait anxiety related to ERPs but not behavioral distractor cost. These findings suggest that trait anxiety modulates visual but not somatosensory processing correlates based on attention. The absence of overt behavioral performance effects suggests compensatory mechanisms may offset underlying differences in sensory processing.

An investigation of the experience of control through the sense of agency in people with obsessive-compulsive disorder: a review and meta-analysis

The construct of sense of agency (SoA) has proven useful for understanding mechanisms underlying obsessive-compulsive disorder (OCD) phenomenology, especially in explaining the apparent dissociation in OCD between actual and perceived control over one's actions. Paradoxically, people with OCD appear to experience both diminished SoA (feeling unable to control their actions) and inflated SoA (having "magical" control over events). The present review investigated the extent to which the SoA is distorted in OCD, in terms of both implicit (ie, inferred from correlates and outcomes of voluntary actions) and explicit (ie, subjective judgment of one's control over an outcome) measures of SoA. Our search resulted in 15 studies that met the criteria for inclusion in a meta-analysis, where we also examined the potential moderating effects of the type of measure (explicit versus implicit) and of the actual control participants had over the outcome. We found that participants with OCD or with high levels of OCD symptoms show lower implicit measures of SoA and at the same time tend to overestimate their control in situations where they do not actually have it. Together, these findings support the hypothesized dissociation in OCD between actual and perceived control over one's actions.

Exploring functional connectivity in large-scale brain networks in obsessive-compulsive disorder: a systematic review of EEG and fMRI studies

Obsessive-compulsive disorder (OCD) is a debilitating psychiatric condition that is difficult to treat due to our limited understanding of its pathophysiology. Functional connectivity in brain networks, as evaluated through neuroimaging studies, plays a pivotal role in understanding OCD. While both electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) have been extensively employed in OCD research, few have fully synthesized their findings. To bridge this gap, we reviewed 166 studies (10 EEG, 156 fMRI) published up to December 2023. In EEG studies, OCD exhibited lower connectivity in delta and alpha bands, with inconsistent findings in other frequency bands. Resting-state fMRI studies reported conflicting connectivity patterns within the default mode network (DMN) and sensorimotor cortico-striato-thalamo-cortical (CSTC) circuitry. Many studies observed decreased resting-state connectivity between the DMN and salience network (SN), implicating the 'triple network model' in OCD. Task-related hyperconnectivity within the DMN-SN and hypoconnectivity between the SN and frontoparietal network suggest OCD-related cognitive inflexibility, potentially due to triple network dysfunction. In conclusion, our review highlights diverse connectivity differences in OCD, revealing complex brain network interplay that contributes to symptom manifestation. However, the presence of conflicting findings underscores the necessity for targeted research to achieve a comprehensive understanding of the pathophysiology of OCD.

Obsessive-Compulsive Symptoms in Children Are Related to Sensory Sensitivity and to Seeking Proxies for Internal States

Symptoms of obsessive-compulsive disorder are related to atypical sensory processing, particularly sensory over-responsivity, in both children and adults. In adults, obsessive-compulsive symptoms are also associated with the attenuation of access to the internal state and compensatory reliance on proxies for these states, including fixed rules and rituals. We aimed to examine the associations between sensory over-responsivity, the tendency to seek proxies for internal states, and obsessive-compulsive symptoms in children. Parents of 404 children between 5 and 10 years of age completed online measures of obsessive-compulsive symptoms, seeking proxies for internal states, sensory over-responsivity, and anxiety. Linear regression, dominance analysis, and network analysis were used to explore the unique associations between these variables. The tendency to seek proxies for internal states was more strongly associated with obsessive-compulsive symptoms than with anxiety symptoms and uniquely associated with all major obsessive-compulsive symptom dimensions except obsessing. Both the tendency to seek proxies for internal states and sensory over-responsivity were significantly associated with obsessive-compulsive symptoms, but the association was significantly stronger for the tendency to seek proxies for internal states. While limited by the sole reliance on the parent-report, the present study shows that the tendency to seek proxies for internal states could help clarify the developmental processes involved in the onset of obsessive-compulsive symptoms during childhood and that sensory sensitivity may be important to consider in this process.

Pre-movement gating of somatosensory evoked potentials in tourette syndrome

OBJECTIVE

Tourette syndrome (TS) is a neurobehavioral disorder characterized by motor and vocal tics. Simple tics are purposeless involuntary movements that spontaneously resolve during middle adolescence. Complex tics appear to be semi-voluntary movements that may become intractable when associated with obsessive-compulsive disorder (OCD). Sensory tics or urges preceded by tics suggest sensorimotor processing impairment in TS. We aimed to clarify its pathophysiology by exploring the pre-movement gating (attenuation) of somatosensory evoked potentials (SEPs).

METHODS

We examined 42 patients (aged 9-48 years), 4 of whom underwent follow-up assessment, along with 19 healthy controls. We defined patients with only simple tics as TS-S and patients with complex tics as TS-C. Pre-movement gating of SEPs was assessed using a previously described method. Frontal N30 (FrN30) amplitudes were compared between pre-movement and resting states. The gating ratio of pre-movement/resting amplitude of the FrN30 component was assessed: the larger the ratio, the less the gating.

RESULTS

The gating ratio for TS-C patients was larger than that of TS-S patients and healthy controls, but a statistical difference between TS-S and TS-C appeared after 15 years and over (p < 0.001). There were no significant differences in the gating ratio between TS-S patients and healthy controls. The gating ratio was related to the severity of OCD (p < 0.05).

CONCLUSION

Sensorimotor processing was preserved for simple tics but impaired in complex tics, specifically after middle adolescence. Our study supports an age-dependent dysfunction of both motor and non-motor cortico-striato-thalamo-cortical circuits in complex tics. SEP gating seems promising as a tool for assessing age-dependent sensorimotor disintegration in TS.

Functional connectivity abnormalities of brain networks in obsessive–compulsive disorder: a systematic review

Obsessive-compulsive disorder (OCD) is characterized by cognitive abnormalities encompassing several executive processes. Neuroimaging studies highlight functional abnormalities of executive fronto-parietal network (FPN) and default-mode network (DMN) in OCD patients, as well as of the prefrontal cortex (PFC) more specifically. We aim at assessing the presence of functional connectivity (FC) abnormalities of intrinsic brain networks and PFC in OCD, possibly underlying specific computational impairments and clinical manifestations. A systematic review of resting-state fMRI studies investigating FC was conducted in unmedicated OCD patients by querying three scientific databases (PubMed, Scopus, PsycInfo) up to July 2022 (search terms: “obsessive–compulsive disorder” AND “resting state” AND “fMRI” AND “function* *connect*” AND “task-positive” OR “executive” OR “central executive” OR “executive control” OR “executive-control” OR “cognitive control” OR “attenti*” OR “dorsal attention” OR “ventral attention” OR “frontoparietal” OR “fronto-parietal” OR “default mode” AND “network*” OR “system*”). Collectively, 20 studies were included. A predominantly reduced FC of DMN – often related to increased symptom severity – emerged. Additionally, intra-network FC of FPN was predominantly increased and often positively related to clinical scores. Concerning PFC, a predominant hyper-connectivity of right-sided prefrontal links emerged. Finally, FC of lateral prefrontal areas correlated with specific symptom dimensions. Several sources of heterogeneity in methodology might have affected results in unpredictable ways and were discussed. Such findings might represent endophenotypes of OCD manifestations, possibly reflecting computational impairments and difficulties in engaging in self-referential processes or in disengaging from cognitive control and monitoring processes.

Cross-disorder comparison of sensory over-responsivity in chronic tic disorders and obsessive-compulsive disorder

BACKGROUND

Sensory over-responsivity (SOR) refers to excessively intense and/or prolonged behavioral responses to environmental stimuli typically perceived as non-aversive. SOR is prevalent in several neurodevelopmental disorders, including chronic tic disorders (CTDs) and obsessive-compulsive disorder (OCD). Few studies have examined the extent and clinical correlates of SOR across disorders, limiting insights into the phenomenon's transdiagnostic clinical and biological relevance. Such cross-disorder comparisons are of particular interest for CTDs and OCD given their frequent co-occurrence.

OBJECTIVE

We sought to compare the magnitude of SOR between adults with CTD and adults with OCD and to identify the clinical factors most strongly associated with SOR across these disorders.

METHODS

We enrolled 207 age- and sex-matched participants across four diagnostic categories: CTD without OCD (designated "CTD/OCD-"; n = 37), CTD with OCD ("CTD/OCD+"; n = 32), OCD without tic disorder ("OCD"; n = 69), and healthy controls (n = 69). Participants completed a self-report battery of rating scales assessing SOR (Sensory Gating Inventory, SGI), obsessive-compulsive symptoms (Dimensional Obsessive-Compulsive Scale, DOCS), inattention and hyperactivity (Adult ADHD Self-Report Screening Scale for DSM-5, ASRS-5), anxiety (Generalized Anxiety Disorder-7), and depression (Patient Health Questionnaire-9). CTD participants were also administered the Yale Global Tic Severity Scale (YGTSS). To examine between-group differences in SOR, we compared SGI score across all groups and between pairs of groups. To examine the relationship of SOR with other clinical factors, we performed multivariable linear regression.

RESULTS

CTD/OCD-, CTD/OCD+, and OCD participants were 86.7%, 87.6%, and 89.5%, respectively, more likely to have higher SGI total scores than healthy controls. SGI total score did not differ between CTD/OCD-, CTD/OCD+, and OCD groups. In the regression model of log-transformed SGI total score, OCD diagnosis, DOCS score, and ASRS-5 score each contributed significantly to model goodness-of-fit, whereas CTD diagnosis and YGTSS total tic score did not.

CONCLUSION

SOR is prevalent in adults with CTD and in adults with OCD but does not significantly differ in magnitude between these disorders. Across CTD, OCD, and healthy control adult populations, SOR is independently associated with both obsessive-compulsive and ADHD symptoms, suggesting a transdiagnostic relationship between these sensory and psychiatric manifestations. Future cross-disorder, longitudinal, and translational research is needed to clarify the role and prognostic import of SOR in CTDs, OCD, and other neurodevelopmental disorders.

State and Trait Risk and Resilience Factors Associated with COVID-19 Impact and Obsessive-Compulsive Symptom Trajectories

The COVID-19 pandemic may exacerbate common symptoms of obsessive-compulsive disorder, such as fears of contamination or causing harm to others. To investigate the potential impact of COVID-19 on obsessive-compulsive (OC) symptoms, we utilized a frequent sampling prospective design to assess changes in OC symptoms between April 2020 and January 2021. We examined in a broad clinical and non-clinical sample whether baseline risk (e.g., emotion dysregulation, anxiety sensitivity, intolerance of uncertainty) and protective (e.g., resilience) factors would predict OC symptom changes, and whether coping strategies would mediate week-to-week changes in COVID-19 impact and OC symptoms. Emotion dysregulation was associated with greater likelihood of OC symptom worsening, whereas resilience was associated with lower likelihood. Longitudinal mediation analyses revealed that coping strategies were not significant mediators; however, changes in adaptive coping were associated with subsequent-week OC symptom reductions. Regardless of perceived COVID-19 impact, implementing adaptive coping strategies may prospectively reduce OC symptoms.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41811-021-00128-4.

Efficacy and tolerability of repetitive transcranial magnetic stimulation for the treatment of obsessive-compulsive disorder in adults: a systematic review and network meta-analysis

Repetitive transcranial magnetic stimulation (rTMS) has been widely used as an alternative treatment for obsessive-compulsive disorder (OCD). However, the most effective rTMS parameters, such as the targets and stimulation frequencies, remain controversial. Therefore, we aimed to compare and rank the efficacy and tolerability of different rTMS strategies for OCD treatment. We searched five electronic databases from the date of their inception to March 25, 2020. Pairwise meta-analyses and network meta-analyses were performed to synthesize data. We assessed the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. Twenty-two eligible randomized controlled trials (RCTs) were included. For efficacy, low-frequency (LF) rTMS over the dorsolateral prefrontal cortex (DLPFC; mean difference (MD) 6.34, 95% credible interval (CrI) 2.12-10.42) and supplementary motor area (MD 4.18, 95% CrI 0.83-7.62), and high-frequency rTMS over the DLPFC (MD 3.75, 95% CrI 1.04-6.81) were more effective than sham rTMS. Regarding tolerability, all rTMS treatment strategies were similar to the sham rTMS. The estimated ranking probabilities of treatments showed that LF-rTMS over the DLPFC might be the most effective intervention among all rTMS strategies. However, the quality of evidence regarding efficacy was evaluated as very low. Current evidence suggested a marginal advantage for LF-rTMS over the DLPFC on OCD treatment. High-quality RCTs with low selection and performance bias are needed to further verify the efficacy of specific rTMS strategies for the OCD treatment.

Functional connectivity changes and symptoms improvement after personalized, double-daily dosing, repetitive transcranial magnetic stimulation in obsessive-compulsive disorder: A pilot study

BACKGROUND

intrusive thoughts and compulsive behaviors that characterize obsessive compulsive disorder (OCD) are associated to aberrant resting state functional connectivity (rsFC) patterns within the cortico-striatal-thalamo-cortical (CSTC) circuits. A high percentage of OCD patients do not respond to conventional pharmacological treatments or psychotherapy. In these patients, inhibitory repetitive transcranial magnetic stimulation (rTMS) of the Supplementary Motor Area (SMA) resulted in a significant clinical benefit.

METHODS

In the current study, we applied a novel protocol of 1-week MRI-guided individualized double-daily sessions of rTMS treatment (1-Hz; 110% of resting Motor Threshold/7200 pulses/day), to bilateral SMA in 9 OCD patients. We tested its (i) feasibility-safety, (ii) clinical efficacy and (iii) rsFC related changes.

RESULTS

Patients reported no side effects during and after rTMS. Personalized rTMS treatment led to a significant improvement of OCD symptoms (average 25%; p = .005) and persistence of benefit up to 3-month follow-up. rsFC analysis revealed a significant reduction of connectivity patterns between bilateral SMA and subcortical regions, specifically in the basal ganglia and thalamus. Additional analysis showed that OCD symptoms severity correlates with a higher connectivity pattern between bilateral SMA and subcortical regions.

CONCLUSIONS

rTMS double-daily sessions are safe, feasible and effective in OCD. The clinical outcomes, that are consistent with those found in our previous RCT, are linked to a decreased connectivity between SMA and subcortical brain areas implicated in control over obsessions and maladaptive compulsive behavior.

Altered Intramodular Functional Connectivity in Drug Naïve Obsessive-Compulsive Disorder Patients

Modular functional alterations were shown in obsessive-compulsive disorder (OCD) patients from previous functional magnetic resonance imaging (fMRI) studies. However, most studies considered each module as a specific node and ignore the intramodular connectivity information. In this paper, we investigated the intramodular functional connectivity (FC) alterations in drug naïve OCD patients using a whole brain graph theoretical approach for functional modular parcellation. Seventy-three drug-naïve OCD patients and seventy-eight matched healthy controls were included in this study. We utilized infomap algorithm for modules detection. The functional connectivity strength (FCS) was calculated within each module to obtain the FC between a given voxel and all other voxels in the module. We found increased FCS in precentral and postcentral gyrus within sensor-motor network (SMN) and decreased FCS in insula within salience network (SN). Moreover, FC within SMN was negatively correlated with YBOCS- compulsions scores, while FC within SN was negatively correlated with YBOCS-total, compulsions and obsessions scores. Our findings brought useful insights in understanding the pathophysiology of OCD.

Sensory hypersensitivity in Tourette syndrome: A review

Tourette syndrome (TS) is a neurodevelopmental disorder defined by tics, but most patients also experience bothersome sensory phenomena, in the form of premonitory urges and/or sensory hypersensitivity. Whereas premonitory urges are temporally paired with tics, sensory hypersensitivity is a constant, heightened awareness of external and/or internal stimuli. The intensity of sensory hypersensitivity does not strongly correlate with the severity of tics or premonitory urges, suggesting it is a dissociable clinical phenomenon. At least 80% of TS patients report subjectively enhanced perception of various sensory stimuli. These same patients demonstrate normal static detection thresholds. However, individuals with TS habituate abnormally to repetitive stimuli, indicating incapacity to appropriately filter redundant sensory input, i.e. impaired sensory gating. Physiologic support for this hypothesis is provided by abnormal pre-pulse inhibition (PPI) and event-related potential (ERP) investigations. Preclinical data implicates parvalbumin-positive (PV+) interneuron dysfunction in altered sensory gating in TS and other neurodevelopment disorders. Studies probing TS sensory hypersensitivity must methodically account for comorbid psychiatric conditions, namely obsessive compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), and autism spectrum disorder (ASD), as these entities appear to involve pathophysiologic processes shared with TS. The presence of psychiatric comorbidities in TS is associated with even more profound sensory processing dysfunction. A deepened understanding of TS sensory hypersensitivity will afford novel insights into disease mechanisms, clinical phenotype, and therapeutic management.

New potential stimulation targets for noninvasive brain stimulation treatment of chronic insomnia

BACKGROUND

Noninvasive brain stimulation (NIBS) was recently used as a therapeutic application in patients with insomnia. Most of the previous NIBS treatments for insomnia directly selected the dorsolateral prefrontal cortex (DLPFC) as the stimulation site. As the NIBS target is an important factor in the efficacy of NIBS, it is necessary to detect more potential cortical sites for NIBS in insomnia.

METHODS

A neuroimaging study-based meta-analysis was used to examine sleep-related brain regions. A sleep-associated brain region-based functional connectivity (FC) map was constructed in 50 patients with chronic insomnia disorder (CID) without any comorbidity. We also combined the meta-analysis and FC results to examine the potential surface targets for NIBS for CID.

RESULTS

The results identified the bilateral supplementary motor area (SMA), left superior temporal gyrus (STG), bilateral DLPFC, precentral lobule, supramarginal gyrus, angular gyrus, superior frontal gyrus, middle temporal gyrus and middle occipital gyrus as potential brain stimulation targets for insomnia treatment. Notably, the bilateral SMA, right DLPFC and left STG were identified in the FC and meta-analyses. In addition, the SMA and DLPFC were positively and STG was negatively connected with other sleep related brain regions, which indicated inhibitory and excitatory stimulation for NIBS treatment for CID, respectively.

CONCLUSION

Our study suggests the SMA, DLPFC and STG as preferentially selected brain targets of NIBS for CID treatment. We recommend an inhibitory stimulation over SMA and DLPFC, and an excitatory stimulation over STG for NIBS treatment. Future studies should test these new targets using NIBS treatment for insomnia.

Brain functional connectivity in chronic tic disorders and Gilles de la Tourette syndrome

The pathophysiology of chronic tic disorder (cTD) and Gilles de la Tourette syndrome (GTS) is characterized by the dysfunction of both motor and non - motor cortico - striatal - thalamo - cortical (CSTC) circuitries, which leads to tic release and comorbids. A role of fronto - parietal network (FPN) connectivity breakdown has been postulated for tic pathogenesis, given that the FPN entertain connections with limbic, paralimbic, and CSTC networks. Our study was aimed at characterizing the FPN functional connectivity in cTD and GTS in order to assess the role of its deterioration in tic severity and the degree of comorbids. We recorded scalp EEG during resting state in patients with cTD and GTS. The eLORETA current source densities were analyzed, and the lagged phase synchronization (LPS) was calculated to estimate nonlinear functional connectivity between cortical areas. We found that the FPN functional connectivity in delta band was more detrimental in more severe GTS patients. Also, the sensorimotor functional connectivity in beta2 band was stronger in more severe cTD and GTS patients. FPN functional connectivity deterioration correlated with comorbids presence and severity in patients with GTS. Our data suggest that a FPN disconnection may contribute to the motoric symptomatology and comorbid severity in GTS, whereas sensorimotor disconnection may contribute to tic severity in cTD and GTS. Although preliminary, our study points out a differently disturbed brain connectivity between patients with cTD and GTS. This may serve as diagnostic marker and potentially interesting base to develop pharmacological and noninvasive neuromodulation trials aimed at reducing tic symptomatology.

Functional Disruption of Cerebello-thalamo-cortical Networks in Obsessive-Compulsive Disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is characterized by intrusive thoughts and repetitive, compulsive behaviors. Neuroimaging studies have implicated altered connectivity among the functional networks of the cerebral cortex in the pathophysiology of OCD. However, there has been no comprehensive investigation of the cross-talk between the cerebellum and functional networks in the cerebral cortex.

METHODS

This functional neuroimaging study was completed by 44 adult participants with OCD and 43 healthy control participants. We performed large-scale data-driven brain network analysis to identify functional connectivity patterns using resting-state functional magnetic resonance imaging data.

RESULTS

Participants with OCD showed lower functional connectivity within the somatomotor network and greater functional connectivity among the somatomotor network, cerebellum, and subcortical network (e.g., thalamus and pallidum; all p < .005). Network-based statistics analyses demonstrated one component comprising connectivity within the somatomotor network that showed lower connectivity and a second component comprising connectivity among the somatomotor network, and motor regions in particular, and the cerebellum that showed greater connectivity in participants with OCD relative to healthy control participants. In participants with OCD, abnormal connectivity across both network-based statistics-derived components positively correlated with OCD symptom severity (p = .006).

CONCLUSIONS

To our knowledge, this study is the first comprehensive investigation of large-scale network alteration across the cerebral cortex, subcortical regions, and cerebellum in OCD. Our findings highlight a critical role of the cerebellum in the pathophysiology of OCD.

Functional Connectivity of the Striatum as a Neural Correlate of Symptom Severity in Patient with Obsessive-Compulsive Disorder

OBJECTIVE

It is well established that the cortico-striato-thalamo-cortical (CSTC) circuit is implicated in the pathophysiology of obsessive- compulsive disorder (OCD). However, reports on corticostriatal functional connectivity (FC) in OCD have been inconsistent due to the structural and functional heterogeneity of the striatum. Therefore, in the present study, we investigated corticostriatal FC using a fine 12-seed striatal parcellation to overcome this heterogeneity and discover the neural correlates of symptoms in OCD patients.

METHODS

We recruited 23 OCD patients and 23 healthy controls (HCs). Whole-brain FC based on striatal seeds was examined using resting-state functional magnetic resonance imaging data and compared across OCD patients and HCs. We conducted correlation analysis between FCs of striatal subregions with significant group differences and symptom severity scores on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), Hamilton Rating Scale for Depression, and Hamilton Rating Scale for Anxiety (HAM-A).

RESULTS

Compared to HCs, patients demonstrated increased FC of the dorsal caudal putamen and ventral rostral putamen (VRP) with several cortical regions, such as the intracalcarine cortex, inferior frontal gyrus, supramarginal/angular gyrus (SMG/AG), and postcentral gyrus (PCG). Furthermore, FC between the VRP and SMG/AG and between the VRP and PCG was negatively correlated with scores on the Y-BOCS compulsive subscale and the HAM-A, respectively.

CONCLUSION

These findings suggest that striatal subregions have strengthened FC with extensive cortical regions, which may reflect neural correlates of compulsive and anxious symptoms in OCD patients. These results contribute to an improved understanding of OCD pathophysiology by complementing the current evidence regarding striatal FC.

Sensory Hypersensitivity Severity and Association with Obsessive-Compulsive Symptoms in Adults with Tic Disorder

BACKGROUND

Sensory hypersensitivity, defined as heightened awareness of and reactivity to external stimuli, is a bothersome symptom that affects up to 80% of adults with Tourette syndrome (TS). Such widespread prevalence suggests sensory hypersensitivity is a core feature of the disorder, but its severity and association with other clinical features of TS remain largely unexplored. Complicating matters, sensory hypersensitivity has been observed in two neurodevelopmental disorders commonly comorbid with TS: obsessive-compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD).

OBJECTIVE

We sought to measure sensory hypersensitivity in TS patients relative to healthy controls and to investigate the relationship of sensory hypersensitivity with OCD and ADHD symptoms in the context of TS.

METHODS

We recruited 34 adults with TS or chronic tic disorder to undergo evaluation with the Yale Global Tic Severity Scale (YGTSS) and a battery of validated self-report instruments assessing sensory hypersensitivity (Sensory Gating Inventory, SGI; Sensory Perception Quotient, SPQ), premonitory urge (Premonitory Urge to Tic Scale, PUTS), OCD (Dimensional Obsessive-Compulsive Scale, DOCS), and ADHD (Adult ADHD Self-Report Screening Scale for DSM-5, ASRS-V). Age- and sex-matched healthy controls were recruited to complete SGI and psychiatric measures.

RESULTS

SGI and SPQ scores strongly correlated (r _s = -0.73, p < 0.0001) within patients. SGI total score was significantly higher in patients versus controls (119.0 vs 67.6, U =-5.3, p < 0.0001), indicating greater sensory hypersensitivity in the tic disorder group. SGI score correlated modestly with PUTS, DOCS, and ASRS-V scores but not with YGTSS total tic score. Hierarchical linear regression analysis revealed that, of the tested variables, only DOCS score contributed significantly to mean SGI score, with β ranging from 1.03 (p = 0.044) to 1.41 (p = 0.001). A simple linear regression model with DOCS as the independent variable accounted for 31.9% of SGI score variance.

CONCLUSION

Sensory hypersensitivity is prominent in adults with tic disorder and is independently associated with obsessive-compulsive symptom severity.

Review: Exteroceptive Sensory Abnormalities in Childhood and Adolescent Anxiety and Obsessive-Compulsive Disorder: A Critical Review

OBJECTIVE

Childhood anxiety and obsessive-compulsive disorder (OCD) are defined by fear, worry, and uncertainty, but there is also evidence that affected children possess exteroceptive sensory abnormalities. These sensory features may often instigate symptoms and cause significant distress and functional impairment. In addition, a purported class of conditions known as "sensory processing disorders" may significantly overlap with childhood anxiety and OCD, which provides further support for a connection between abnormal sensation and fear-based psychopathology.

METHOD

The current review was conducted to synthesize and to critically evaluate the existing research on exteroceptive sensory abnormalities in childhood anxiety and OCD. Because of the paucity of research in this area, studies with adult populations were also briefly reviewed.

RESULTS

The review found significant support for the notion that sensory abnormalities are common in children with anxiety disorders and OCD, but there are significant limitations to research in this area that prevent firm conclusions.

CONCLUSION

Potential avenues for future research on sensory features of pediatric anxiety and OCD are discussed.

Attenuation of access to internal states in high obsessive-compulsive individuals might increase susceptibility to false feedback: Evidence from a visuo-motor hand-reaching task

BACKGROUND AND OBJECTIVES

The Seeking Proxies for Internal States (SPIS) model of obsessive-compulsive disorder (OCD) posits that obsessive-compulsive (OC) individuals have attenuated access to their internal states. Hence, they seek and rely on proxies, or discernible substitutes for these internal states. In previous studies, participants with high OC tendencies and OCD patients, compared to controls, showed increased reliance on external proxies and were more influenced by false feedback when judging their internal states. This study is the first to examine the effects of false feedback on performance of hand movements in participants with high and low OC tendencies.

METHOD

Thirty-four participants with high OC tendencies and 34 participants with low OC tendencies were asked to perform accurate hand reaches without visual feedback in two separate sessions of a computerized hand-reaching task: once after valid feedback training of their hand location and once with false-rotated feedback. We assessed the accuracy and directional adaptation of participants' reaches.

RESULTS

As predicted, high OC participants evidenced a larger decrease in their hand positioning accuracy after training with false feedback compared to low OC participants.

LIMITATIONS

The generalization of our findings to OCD requires replication with a clinical sample.

CONCLUSIONS

These results suggest that in addition to self-perceptions, motor performance of OC individuals is prone to be overly influenced by false feedback, possibly due to attenuated access to proprioceptive cues. These findings may be particularly relevant to understanding the distorted sense of agency in OCD.

Abnormalities within and beyond the cortico-striato-thalamo-cortical circuitry in medication-free patients with OCD revealed by the fractional amplitude of low-frequency fluctuations and resting-state functional connectivity

Neuroimaging studies of obsessive-compulsive disorder (OCD) often focus on the cortico-striato-thalamo-cortical (CSTC) circuitry, but recent studies have found abnormal spontaneous brain activity in regions outside the CSTC circuitry in patients with OCD using resting-state functional magnetic resonance imaging. Researchers have not clearly determined whether changes in spontaneous brain activity within and beyond the CSTC circuitry coexist in medication-free patients with OCD. To address this question, we recruited 64 medication-free patients with OCD and 60 matched healthy controls (HCs) to investigate their spontaneous brain activity by measuring the fractional amplitude of low-frequency fluctuation (fALFF) and resting-state functional connectivity. Patients with OCD showed increased fALFF values in the left dorsolateral prefrontal cortex (DLPFC) and decreased fALFF values in the right rolandic operculum compared with HCs. Furthermore, patients with OCD exhibited significantly increased functional connectivity between the left DLPFC and the left cerebellum and reduced negative functional connectivity between the right rolandic operculum and the left precuneus. These findings provided new insights into the pathophysiological model of OCD, which may include CSTC circuitry and regions outside this circuitry.

Translating striatal activity from brain slice to whole animal neurophysiology: A guide for neuroscience research integrating diverse levels of analysis

An important goal of this review is highlighting research in neuroscience as examples of multilevel functional and anatomical analyses addressing basic science issues and applying results to the understanding of diverse disorders. The research of Dr. Michael Levine, a leader in neuroscience, exemplifies this approach by uncovering fundamental properties of basal ganglia function and translating these findings to clinical applications. The review focuses on neurophysiological research connecting results from in vitro and in vivo recordings. A second goal is to utilize these research connections to produce novel, accurate descriptions for corticostriatal processing involved in varied, complex functions. Medium spiny neurons in striatum act as integrators combining input with baseline activity creating motivational "events." Basic research on corticostriatal synapses is described and links developed to issues with clinical relevance such as inhibitory gating, self-injurious behavior, and relative reward valuation. Work is highlighted on dopamine-glutamate interactions. Individual medium spiny neurons express both D₁ and D₂ receptors and encode information in a bivalent manner depending upon the mix of receptors involved. Current work on neurophysiology of reward processing has taken advantage of these basic approaches at the cellular and molecular levels. Future directions in studying physiology of reward processing and action sequencing could profit by incorporating the divergent ways dopamine modulates incoming neurochemical signals. Primary investigators leading research teams should mirror Mike Levine's efforts in "climbing the mountain" of scientific inquiry by performing analyses at different levels of inquiry, integrating the findings, and building comprehensive answers to problems unsolvable without this bold approach.

Mapping Alterations of the Functional Structure of the Cerebral Cortex in Obsessive–Compulsive Disorder

We mapped alterations of the functional structure of the cerebral cortex using a novel imaging approach in a sample of 160 obsessive–compulsive disorder (OCD) patients. Whole-brain functional connectivity maps were generated using multidistance measures of intracortical neural activity coupling defined within isodistant local areas. OCD patients demonstrated neural activity desynchronization within the orbitofrontal cortex and in primary somatosensory, auditory, visual, gustatory, and olfactory areas. Symptom severity was significantly associated with the degree of functional structure alteration in OCD-relevant brain regions. By means of a novel imaging perspective, we once again identified brain alterations in the orbitofrontal cortex, involving areas purportedly implicated in the pathophysiology of OCD. However, our results also indicated that weaker intracortical activity coupling is also present in each primary sensory area. On the basis of previous neurophysiological studies, such cortical activity desynchronization may best be interpreted as reflecting deficient inhibitory neuron activity and altered sensory filtering.

Noninvasive brain stimulation in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a complex neuropsychiatric disorder with a chronic course, contributing to significant socio-occupational dysfunction. Forty percent of patients remain treatment refractive despite mainstream treatment options such as serotonin-reuptake inhibitors and cognitive behavior therapy. Noninvasive brain stimulation approaches such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) have piqued interest as add-on treatment options in OCD. This review focuses on summarizing the TMS and tDCS studies in OCD with respect to their study design and stimulation parameters and key findings. We also briefly discuss the limitations and future directions noninvasive brain stimulation in OCD.

Atypical symptom presentations in children and adolescents with obsessive compulsive disorder

BACKGROUND

Common symptom presentations in youth with Obsessive Compulsive Disorder (OCD) are easily recognized and are included in the Children's Yale Brown Obsessive Compulsive Scale (CY-BOCS) symptom checklist. However, some youth may occasionally present with atypical or unusual symptoms that are less readily recognized as OCD and may be confused with other disorders that sometimes overlap, such as autism spectrum disorder or even psychosis.

METHODS

Case synopses which are thematically linked and exemplify and illustrate two distinct types of unusual or atypical symptom presentations are described. These symptoms are embedded in the subjects' broader clinical picture, that more correctly identifies the atypical symptoms as a variant feature of OCD rather than some other diagnostic condition.

RESULTS

We describe twenty-four children with OCD. Twelve children had obsessions related to adverse experiences of places, times or other people that were felt as horrific, abhorrent or disgusting. These obsessions led to contamination fears of any thoughts or actions associated with those places, events or people. In those whose OCD was a reaction to another person, the contamination obsession often took the form of fear of acquiring an unwanted trait or characteristic by association, which was then avoided. Twelve other youth had obsessions driven by a primary sensory experience that was intolerable, including tactile, olfactory, and auditory stimuli. These sensory experiences were sometimes linked to specific objects or people, driving time-consuming repetitive behaviors to avoid or alleviate the sensory discomfort.

CONCLUSION

Recognition of atypical presentations of OCD, such as fear of contamination by association with adverse experiences and primary sensory intolerance leading to OCD will help clinicians to better identify and treat these unique symptoms.

A Meta-Analysis of the Effectiveness of Different Cortical Targets Used in Repetitive Transcranial Magnetic Stimulation (rTMS) for the Treatment of Obsessive-Compulsive Disorder (OCD)

Randomised and sham-controlled trials (RCTs) of repetitive transcranial magnetic stimulation (rTMS) in the treatment of obsessive-compulsive disorder (OCD) have yielded conflicting results, which may be due to the variability in rTMS parameters used. We performed an updated systematic review and meta-analysis on the effectiveness of rTMS for the treatment of OCD and aimed to determine whether certain rTMS parameters, such as cortical target, may be associated with higher treatment effectiveness. After conducting a systematic literature review for RCTs on rTMS for OCD through to 1 December 2016 using MEDLINE, PubMed, Web of Science, PsycINFO, Google, and Google Scholar, we performed a random-effects meta-analysis with the outcome measure as pre-post changes in Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores. To determine whether rTMS parameters may have influenced treatment effectiveness, studies were further analysed according to cortical target, stimulation frequency, and length of follow-up. Data were obtained from 18 RCTs on rTMS in the treatment of OCD. Overall, rTMS yielded a modest effect in reducing Y-BOCS scores with Hedge's g of 0.79 (95% CI = 0.43-1.15, p < 0.001). Stimulation of the supplementary motor area yielded the greatest reductions in Y-BOCS scores relative to other cortical targets. Subgroup analyses suggested that low frequency rTMS was more effective than high frequency rTMS. The effectiveness of rTMS was also greater at 12 weeks follow-up than at four weeks follow-up. Our meta-analysis implies that low frequency rTMS applied over the supplementary motor area may offer the greatest effectiveness in the treatment of OCD. The therapeutic effects of rTMS also appear to persist post-treatment and may offer beneficial long-term effectiveness. With our findings, it is suggested that future large-scale studies focus on the supplementary motor area and include follow-up periods of 12 weeks or more.

High obsessive-compulsive individuals may have attenuated access to internal cues associated with active movement: Evidence from a head repositioning study

BACKGROUND AND OBJECTIVES

The Seeking Proxies for Internal States model of OCD posits that obsessive-compulsive (OC) individuals have attenuated access to their internal states. Consequently, they seek and rely on discernible substitutes for these internal states. Previous research has supported these conjectures. Other studies, using a variety of measures, reported a reduced sense of agency (SoA) in OCD. The current study aimed to connect these two bodies of research by focusing on internal signals associated with active movement, which are related to the SoA. We hypothesized that the performance accuracy of high OC participants would be similar for active and passive movements, while that of low OC participants would be higher when the movement is acquired actively.

METHOD

Participants with high vs. low OC tendencies were asked to reposition their head to a target angle that was acquired actively or passively. This was repeated with eyes blindfolded to evaluate reliance on visual information. Accuracy of repositioning was measured with a cervical range-of-motion device.

RESULTS

As predicted, while low OC participants presented a significant decrease in their accuracy after passive (compared to active) acquisition, high OC participants' accuracy did not differ between acquisition types. Contrary to our predictions, reliance on vision was similar across groups.

LIMITATIONS

The generalization of our findings to OCD requires replication with a clinical sample.

CONCLUSIONS

This study implies that high OC individuals have a deficient access to internal cues involved in active movement. This might contribute to their doubt regarding their actions and to their reduced SoA.

Brain alterations in low-frequency fluctuations across multiple bands in obsessive compulsive disorder

The extent of functional abnormalities in frontal-subcortical circuits in obsessive-compulsive disorder (OCD) is still unclear. Although neuroimaging studies, in general, and resting-state functional Magnetic Resonance Imaging (rs-fMRI), in particular, have provided relevant information regarding such alterations, rs-fMRI studies have been typically limited to the analysis of between-region functional connectivity alterations at low-frequency signal fluctuations (i.e., <0.08 Hz). Conversely, the local attributes of Blood Oxygen Level Dependent (BOLD) signal across different frequency bands have been seldom studied, although they may provide valuable information. Here, we evaluated local alterations in low-frequency fluctuations across different oscillation bands in OCD. Sixty-five OCD patients and 50 healthy controls underwent an rs-fMRI assessment. Alterations in the fractional amplitude of low-frequency fluctuations (fALFF) were evaluated, voxel-wise, across four different bands (from 0.01 Hz to 0.25 Hz). OCD patients showed decreased fALFF values in medial orbitofrontal regions and increased fALFF values in the dorsal-medial prefrontal cortex (DMPFC) at frequency bands <0.08 Hz. This pattern was reversed at higher frequencies, where increased fALFF values also appeared in medial temporal lobe structures and medial thalamus. Clinical variables (i.e., symptom-specific severities) were associated with fALFF values across the different frequency bands. Our findings provide novel evidence about the nature and regional distribution of functional alterations in OCD, which should contribute to refine neurobiological models of the disorder. We suggest that the evaluation of the local attributes of BOLD signal across different frequency bands may be a sensitive approach to further characterize brain functional alterations in psychiatric disorders.

Abnormal perceptual sensitivity in body-focused repetitive behaviors

OBJECTIVE

Several compulsive grooming habits such as hair pulling, skin picking, and nail biting are collectively known as body-focused repetitive behaviors (BFRBs). Although subclinical BFRBs are common and benign, more severe and damaging manifestations exist that are difficult to manage. Researchers have suggested that BFRBs are maintained by various cognitive, affective, and sensory contingencies. Although the involvement of cognitive and affective processes in BFRBs has been studied, there is a paucity of research on sensory processes.

METHODS

The current study tested whether adults with subclinical or clinical BFRBs would report abnormal patterns of sensory processing as compared to a healthy control sample.

RESULTS

Adults with clinical BFRBs (n = 26) reported increased sensory sensitivity as compared to persons with subclinical BFRBs (n = 48) and healthy individuals (n = 33). Elevations in sensation avoidance differentiated persons with clinical versus subclinical BFRBs. Sensation seeking patterns were not different between groups. Unexpectedly, BFRB severity was associated with lower registration of sensory stimuli, but this finding may be due to high psychiatric comorbidity rates in the BFRB groups.

CONCLUSIONS

These findings suggest that several sensory abnormalities may underlie BFRBs. Implications for the etiology and treatment of BFRBs are discussed.

Differential modulation of the auditory steady state response and inhibitory gating by chloral hydrate anesthesia

Auditory steady state response (ASSR) and inhibitory gating (IG) are electrophysiological examinations commonly used to evaluate the sensory and cognitive functions of the brain. In some clinic examinations and animal experiments, general anesthesia is necessary to conduct electrophysiological recordings. However, the effects of anesthesia on ASSR and IG remain unclear. For this reason, we recorded local field potentials though electrodes implanted in different brain areas of rats: the auditory cortex (AC), hippocampus (HC), amygdala (AMY), and prefrontal cortex (PFC), and compared the characteristics of ASSR and IG under anesthetized and conscious conditions. We found that ASSR signals were the strongest in the AC, and decreased sequentially in the HP, AMY, and PFC. Chloral hydrate anesthesia significantly reduced the power and phase-locking of ASSR in the AC, HP, and AMY. In contrast, the extent of IG in the AC was weakest and it increased sequentially in the HP, AMY, and PFC. Anesthesia had less effect on the extent of IG. Our results suggest that ASSR and IG may originate from different neural circuits and that IG is more resistant to general anesthesia and therefore better suited to examining the functioning of non-auditory brain regions.

Low frequency fluctuation of brain spontaneous activity and obsessive-compulsive symptoms in a large school-age sample

BACKGROUND

The present study was designed to explore alterations in brain dynamics at rest that are associated with Obsessive Compulsive Symptoms (OCS) in childhood by measuring low frequency fluctuation of spontaneous brain activity in a large school community sample from a developing country.

METHOD

Resting state functional magnetic resonance imaging data were collected in a sample of 655 children and adolescents (6-15 years old) from the brazilian 'High Risk Cohort Study for Psychiatric Disorders (HRC)'. OCS were assessed using items from the Compulsion and Obsessions section of the Development and Well-Being Assessment (DAWBA). The correlation between the fractional amplitude of low frequency fluctuations (fALFF) and the number of OCS were explored by using a general linear model, considering fALFF as response variable, OCS score as regressor and age, gender and site as nuisance variables.

RESULTS

The number of OCS was positively correlated with the fALFF coefficients at the right sensorimotor cortex (pre-motor, primary motor cortex and post-central gyrus) and negatively correlated with the fALFF coefficients at the insula/superior temporal gyrus of both hemispheres. Our results were specific to OCS and not due to associations with overall psychopathology.

CONCLUSIONS

Our results suggest that brain spontaneous activity at rest in the sensorimotor and insular/superior-temporal cortices may be involved in OCS in children. These findings need independent replication and future studies should determine whether brain spontaneous activity changes within these regions might be predictors of risk for obsessive-compulsive disorder latter in life.

The Sense of Agency Scale: A Measure of Consciously Perceived Control over One's Mind, Body, and the Immediate Environment

The sense of agency (SoA) is defined as “the registration that I am the initiator of my actions.” Both “direct” and “indirect” measurement of SoA has focused on specific contextualized perceptual events, however it has also been demonstrated that “higher level” cognitions seemingly affect the SoA. We designed a measure of person's general, context-free beliefs about having core agency—the Sense of Agency Scale (SoAS). An exploratory (EFA) and confirmatory (CFA) factor analyses on samples of 236 (Study 1) and 408 (Study 2) participants yielded two correlated factors we labeled Sense of Positive Agency (SoPA) and Sense of Negative Agency (SoNA). The construct validity of SoAS is demonstrated by its low-to-moderate correlations with conceptually relevant tools and by the moderate-strong relationship between the SoNA subscale and obsessive-compulsive (OC) symptoms (r = 0.35). We conclude that the SoAS seems to isolate people's general beliefs in their agency from their perceived success in obtaining outcomes.

Effects of mastication on human somatosensory processing: A study using somatosensory-evoked potentials

The aim of the present study was to investigate the effects of mastication on somatosensory processing using somatosensory-evoked potentials (SEPs). Fourteen healthy subjects received a median nerve stimulation at the right wrist under two conditions: Mastication and Control. SEPs were recorded in five sessions for approximately seven minutes: Pre, Post 1, 2, 3, and 4. Subjects were asked to chew gum for five minutes after one session in Mastication. Control included the same five sessions. The amplitudes and latencies of P14, N20, P25, N35, P45, and N60 components at C3', frontal N30 component at Fz, and P100 and N140 components at Pz were analyzed. The amplitude of P45-N60 was significantly smaller at Post 1, 2, 3, and 4 than at Pre in Control, but not in Mastication. The latency of P25 was significantly longer at Post 2, 3, and 4 than at Pre in Control, but not in Mastication. The latency of P100 was significantly longer at Post 2 than at Pre in Control, but not in Mastication. These results suggest the significant effects of mastication on the neural activity of human somatosensory processing.

Successful use of transcranial magnetic stimulation in difficult to treat hypersexual disorder

Hypersexual disorder has phenomenological resemblance with impulsive-compulsive spectrum disorders. Inhibitory repetitive transcranial magnetic stimulation (rTMS) over the supplementary motor area (SMA) has been found to be effective in the management of impulsive-compulsive behaviors. Inhibitory rTMS over SMA may be helpful in hypersexual disorder. We highlight here a case of hypersexual disorder (excessive sexual drive) who failed to respond adequately to the conventional pharmacological treatment and responded with rTMS augmentation.

Transcutaneous electrical acupoint stimulation as an adjunct therapy for obsessive-compulsive disorder: A randomized controlled study

BACKGROUND

Transcutaneous electrical acupoint stimulation (TEAS) is thought to have potential to treat obsessive-compulsive disorder (OCD).

OBJECTIVE

The purpose of this study was to determine whether adding TEAS to cognitive behavioral therapy (CBT) and clomipramine would improve the efficacy of these conventional treatments in OCD.

METHODS

In this randomized controlled trial, 360 OCD patients were assigned to receive TEAS combined with CBT plus clomipramine (Group A, n = 120), TEAS combined with CBT plus placebo (Group B, n = 120), and simulated (placebo) TEAS combined with CBT plus clomipramine (Group C, n = 120) for 12 weeks. The primary outcome was measured using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS).

RESULTS

OCD symptoms in all patients reduced over time, however Groups A and B had a significantly greater reduction in Y-BOCS total score and the subscale for obsession and compulsion between week 2 and week 12 compared to Group C. Groups A and B had similar scores on these measures. Both groups had significantly higher rates of clinical response than Group C (88.3% and 81.7% vs. 67.5%, respectively, p < 0.001); and higher rates of remission (30.0% and 22.5% vs. 9.2%, respectively, p < 0.001). Group B experienced fewer adverse events than the other two groups.

CONCLUSIONS

TEAS enhances the efficacy of conventional OCD interventions and avoids the adverse effects associated with conventional pharmacological treatment. It can be considered as an effective adjunct intervention for OCD.

Motor cortical excitability in obsessive-compulsive disorder: Transcranial magnetic stimulation study

OBJECTIVES

Transcranial magnetic stimulation is a non-invasive method of stimulating the brain that is increasingly being used in neuropsychiatric research. Previous work has suggested that the pathophysiology of obsessive-compulsive disorder (OCD) may involve dysfunction of excitatory and/or inhibitory brain function. This study aimed to extend those findings.

METHODS

The study included 45 OCD patients and 15 age- and sex-matched healthy volunteers. Clinical evaluation was conducted using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), Hamilton Anxiety Rating Scale (HAM-A), and Clinical Global Impression rating scale (CGI). Physiological measures were resting and active motor thresholds (RMT and AMT), motor evoked potential (MEP) amplitude, cortical silent period (CSP) and transcallosal inhibition (TCI) durations, short-interval intracortical inhibition (SICI), and intracortical facilitation.

RESULTS

RMT and AMT were significantly lower in patients than in the control group. The mean duration of the CSP and TCI were also significantly shorter. Obsessive trait was associated with significant reduction of TCI duration compared to compulsive trait. There was significant reduction in SICI in OCD patients compared to controls. There were no significant correlations between the Y-BOCS, HAM-A and CGI scores and the cortical excitability parameters.

CONCLUSION

These results provide further evidence for inhibitory deficits or increased facilitation in cortical circuits of patients with OCD.

Things happen: Individuals with high obsessive-compulsive tendencies omit agency in their spoken language

The study examined the prediction that obsessive-compulsive tendencies are related to an attenuated sense of agency (SoA). As most explicit agency judgments are likely to reflect also motivation for and expectation of control, we examined agency in sentence production. Reduced agency can be expressed linguistically by omitting the agent or by using grammatical framings that detach the event from the entity that caused it. We examined the use of agentic language of participants with high vs. low scores on a measure of obsessive-compulsive (OC) symptoms, using structured linguistic tasks in which sentences are elicited in a conversation-like setting. As predicted, high OC individuals produced significantly more non-agentic sentences than low OC individuals, using various linguistic strategies. The results suggest that OC tendencies are related to attenuated SoA. We discuss the implications of these findings for explicating the SoA in OCD and the potential contribution of language analysis for understanding psychopathology.

Brain structural correlates of sensory phenomena in patients with obsessive-compulsive disorder

BACKGROUND

Sensory phenomena (SP) are uncomfortable feelings, including bodily sensations, sense of inner tension, "just-right" perceptions, feelings of incompleteness, or "urge-only" phenomena, which have been described to precede, trigger or accompany repetitive behaviours in individuals with obsessive-compulsive disorder (OCD). Sensory phenomena are also observed in individuals with tic disorders, and previous research suggests that sensorimotor cortex abnormalities underpin the presence of SP in such patients. However, to our knowledge, no studies have assessed the neural correlates of SP in patients with OCD.

METHODS

We assessed the presence of SP using the University of São Paulo Sensory Phenomena Scale in patients with OCD and healthy controls from specialized units in São Paulo, Brazil, and Barcelona, Spain. All participants underwent a structural magnetic resonance examination, and brain images were examined using DARTEL voxel-based morphometry. We evaluated grey matter volume differences between patients with and without SP and healthy controls within the sensorimotor and premotor cortices.

RESULTS

We included 106 patients with OCD and 87 controls in our study. Patients with SP (67% of the sample) showed grey matter volume increases in the left sensorimotor cortex in comparison to patients without SP and bilateral sensorimotor cortex grey matter volume increases in comparison to controls. No differences were observed between patients without SP and controls.

LIMITATIONS

Most patients were medicated. Participant recruitment and image acquisition were performed in 2 different centres.

CONCLUSION

We have identified a structural correlate of SP in patients with OCD involving grey matter volume increases within the sensorimotor cortex; this finding is in agreement with those of tic disorder studies showing that abnormal activity and volume increases within this region are associated with the urges preceding tic onset.

Transcranial cortical stimulation in the treatment of obsessive-compulsive disorders: efficacy studies

Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are non-invasive brain stimulation methods that became widely used as therapeutic tools during the past two decades especially in cases of depression and schizophrenia. Low frequency rTMS and cathodal effect of tDCS inhibits cortical functioning while high frequency and anodal effect of tDCS have the opposite effect. Prolonged and repetitive application of either methods leads to changes in excitability of the human cortex that outlast the period of stimulation. Both rTMS and tDCS induce functional changes in the brain-modulating neural activity at cortical level. This paper reviews rTMS and tDCS effects in clinical trials for obsessive-compulsive disorder (OCD). Low frequency rTMS, particularly targeting the supplementary motor area and the orbital frontal cortex, seems to be the most promising in terms of therapeutic efficacy while older studies targeting the prefrontal dorsal cortex were not as successful. tDCS clearly needs to be investigated in large scale and sufficiently powered randomized control studies. From a general point of view, these non-invasive techniques hold promise as novel therapeutic tools for OCD patients.

Influence of emotional states on inhibitory gating: animals models to clinical neurophysiology

Integrating research efforts using a cross-domain approach could redefine traditional constructs used in behavioral and clinical neuroscience by demonstrating that behavior and mental processes arise not from functional isolation but from integration. Our research group has been examining the interface between cognitive and emotional processes by studying inhibitory gating. Inhibitory gating can be measured via changes in behavior or neural signal processing. Sensorimotor gating of the startle response is a well-used measure. To study how emotion and cognition interact during startle modulation in the animal model, we examined ultrasonic vocalization (USV) emissions during acoustic startle and prepulse inhibition. We found high rates of USV emission during the sensorimotor gating paradigm and revealed links between prepulse inhibition (PPI) and USV emission that could reflect emotional and cognitive influences. Measuring inhibitory gating as P50 event-related potential suppression has also revealed possible connections between emotional states and cognitive processes. We have examined the single unit responses during the traditional gating paradigm and found that acute and chronic stress can alter gating of neural signals in regions such as amygdala, striatum and medial prefrontal cortex. Our findings point to the need for more cross-domain research on how shifting states of emotion can impact basic mechanisms of information processing. Results could inform clinical work with the development of tools that depend upon cross-domain communication, and enable a better understanding and evaluation of psychological impairment.

Global resting-state functional magnetic resonance imaging analysis identifies frontal cortex, striatal, and cerebellar dysconnectivity in obsessive-compulsive disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is associated with regional hyperactivity in cortico-striatal circuits. However, the large-scale patterns of abnormal neural connectivity remain uncharacterized. Resting-state functional connectivity studies have shown altered connectivity within the implicated circuitry, but they have used seed-driven approaches wherein a circuit of interest is defined a priori. This limits their ability to identify network abnormalities beyond the prevailing framework. This limitation is particularly problematic within the prefrontal cortex (PFC), which is large and heterogeneous and where a priori specification of seeds is therefore difficult. A hypothesis-neutral, data-driven approach to the analysis of connectivity is vital.

METHODS

We analyzed resting-state functional connectivity data collected at 3T in 27 OCD patients and 66 matched control subjects with a recently developed data-driven global brain connectivity (GBC) method, both within the PFC and across the whole brain.

RESULTS

We found clusters of decreased connectivity in the left lateral PFC in both whole-brain and PFC-restricted analyses. Increased GBC was found in the right putamen and left cerebellar cortex. Within regions of interest in the basal ganglia and thalamus, we identified increased GBC in dorsal striatum and anterior thalamus, which was reduced in patients on medication. The ventral striatum/nucleus accumbens exhibited decreased global connectivity but increased connectivity specifically with the ventral anterior cingulate cortex in subjects with OCD.

CONCLUSIONS

These findings identify previously uncharacterized PFC and basal ganglia dysconnectivity in OCD and reveal differentially altered GBC in dorsal and ventral striatum. Results highlight complex disturbances in PFC networks, which could contribute to disrupted cortical-striatal-cerebellar circuits in OCD.

Modulation of motor cortex excitability in obsessive-compulsive disorder: an exploratory study on the relations of neurophysiology measures with clinical outcome

Low-frequency repetitive transcranial magnetic stimulation (rTMS) to supplementary motor area (SMA) showed clinical benefit in obsessive-compulsive disorder (OCD). Here we tested whether clinical improvement was associated with enhanced cortical inhibition as measured by single and paired-pulse TMS variables. In 18 OCD patients receiving 4 weeks of either active or sham rTMS in a double-blind randomized trial, we assessed bilateral resting and active motor thresholds (RMT and AMT), cortical silent period (CSP), short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF). We tested correlations between changes in Yale-Brown Obsessive Compulsive Scale-Self-report (Y-BOCS-SR), Clinical Global Impression-Severity subscale (CGI-S) and cortical excitability measures. Active rTMS increased right hemisphere RMT whose change correlated with Y-BOCS-SR improvement. Baseline RMT hemispheric asymmetry, defined as the difference between left and right hemispheres RMT, and its normalization after active rTMS correlated with Y-BOCS-SR and CGI-S improvements. Active rTMS also increased right hemisphere SICI whose change correlated with Y-BOCS-SR and CGI-S at week 4, and with normalization of baseline RMT hemispheric asymmetry. Treatment-induced changes in cortical excitability measures are consistent with an inhibitory action of SMA rTMS on dysfunctional motor circuits in OCD. Correlations of neurophysiology measures with therapeutic outcome are supportive of the role of SMA in the modulation of OCD symptoms.

Neuromodulation for obsessive-compulsive disorder

This article describes the basis for neuromodulation procedures for obsessive-compulsive disorder (OCD) and summarizes the literature on the efficacy of these interventions. Discussion includes neural circuitry underlying OCD pathology, the history and types of ablative procedures, the targets and modalities used for neuromodulation, and future therapeutic directions.