Neural correlates of working memory deficits and associations to response inhibition in obsessive compulsive disorder

Heart rate and heart rate variability in obsessive-compulsive disorder: Evidence from patients and unaffected first-degree relatives

Altered heart rate (HR) and heart rate variability (HRV) are common observations in psychiatric disorders. Yet, few studies have examined these cardiac measures in obsessive-compulsive disorder (OCD). The current study aimed to investigate HR and HRV, indexed by the root mean square of successive differences (RMSSD) and further time domain indices, as putative biological characteristics of OCD. Electrocardiogram was recorded during a five-minute resting state. Group differences between patients with OCD (n = 96), healthy participants (n = 112), and unaffected first-degree relatives of patients with OCD (n = 47) were analyzed. As potential moderators of group differences, we examined the influence of age and medication, respectively. As results indicated, patients with OCD showed higher HR and lower HRV compared to healthy participants. These group differences were not moderated by age. Importantly, subgroup analyses showed that only medicated patients displayed lower HRV compared to healthy individuals, while HR alterations were evident in unmedicated patients. Regarding unaffected first-degree relatives, group differences in HRV remained at trend level. Further, an age-moderated group differentiation showed that higher HRV distinguished relatives from healthy individuals in young adulthood, whereas at higher age lower HRV was indicative of relatives. Both the role of familial risk and medication in HRV alterations need further elucidation. Pending future studies, alterations in HR and potentially HRV might serve as useful indices to characterize the pathophysiology of OCD.

Opening new vistas on obsessive-compulsive disorder with the observing response task

Obsessive-compulsive disorder (OCD), a highly prevalent and debilitating disorder, is incompletely understood in terms of underpinning behavioural, psychological, and neural mechanisms. This is attributable to high symptomatic heterogeneity; cardinal features comprise obsessions and compulsions, including clinical subcategories. While obsessive and intrusive thoughts are arguably unique to humans, dysfunctional behaviours analogous to those seen in clinical OCD have been examined in nonhuman animals. Genetic, ethological, pharmacological, and neurobehavioural approaches all contribute to understanding the emergence and persistence of compulsive behaviour. One behaviour of particular interest is maladaptive checking, whereby human patients excessively perform checking rituals despite these serving no purpose. Dysfunctional and excessive checking is the most common symptom associated with OCD and can be readily operationalised in rodents. This review considers animal models of OCD, the neural circuitries associated with impairments in habit-based and goal-directed behaviour, and how these may link to the compulsions observed in OCD. We further review the Observing Response Task (ORT), an appetitive instrumental learning procedure that distinguishes between functional and dysfunctional checking, with translational application in humans and rodents. By shedding light on the psychological and neural bases of compulsive-like checking, the ORT has potential to offer translational insights into the underlying mechanisms of OCD, in addition to being a platform for testing psychological and neurochemical treatment approaches.

Targeting the prefrontal-supplementary motor network in obsessive-compulsive disorder with intensified electrical stimulation in two dosages: a randomized, controlled trial

Obsessive-compulsive disorder (OCD) is associated with a high disease burden, and treatment options are limited. We used intensified electrical stimulation in two dosages to target a main circuitry associated with the pathophysiology of OCD, left dorsolateral prefrontal cortex (l-DLPFC), and pre-supplementary motor area (pre-SMA) and assessed clinical outcomes, neuropsychological performance, and brain physiology. In a double-blind, randomized controlled trial, thirty-nine patients with OCD were randomly assigned to three groups of sham, 2-mA, or 1-mA transcranial direct current stimulation (tDCS) targeting the l-DLPFC (F3) and pre-SMA (FC2) with anodal and cathodal stimulation respectively. The treatment included 10 sessions of 20-minute stimulation delivered twice per day with 20-min between-session intervals. Outcome measures were reduction in OCD symptoms, anxiety, and depressive states, performance on a neuropsychological test battery (response inhibition, working memory, attention), oscillatory brain activities, and functional connectivity. All outcome measures except EEG were examined at pre-intervention, post-intervention, and 1-month follow-up times. The 2-mA protocol significantly reduced OCD symptoms, anxiety, and depression states and improved quality of life after the intervention up to 1-month follow-up compared to the sham group, while the 1-mA protocol reduced OCD symptoms only in the follow-up and depressive state immediately after and 1-month following the intervention. Both protocols partially improved response inhibition, and the 2-mA protocol reduced attention bias to OCD-related stimuli and improved reaction time in working memory performance. Both protocols increased alpha oscillatory power, and the 2-mA protocol decreased delta power as well. Both protocols increased connectivity in higher frequency bands at frontal-central areas compared to the sham. Modulation of the prefrontal-supplementary motor network with intensified tDCS ameliorates OCD clinical symptoms and results in beneficial cognitive effects. The 2-mA intensified stimulation resulted in larger symptom reduction and improved more converging outcome variables related to therapeutic efficacy. These results support applying the intensified prefrontal-SMA tDCS in larger trials.

A network perspective on cognitive function and obsessive-compulsive related symptoms

BACKGROUND

The relationship between cognitive function and psychopathological symptoms has been an important research field in recent years. Previous studies have typically applied case-control designs to explore differences in certain cognitive variables. Multivariate analyses are needed to deepen our understanding of the intercorrelations among cognitive and symptom phenotypes in OCD.

METHODS

The present study used network analysis to construct networks of cognitive variables and OCD-related symptoms in patients with OCD and healthy controls (N = 226), aiming to explore the relationship among numerous cognitive function variables and OCD-related symptoms in detail and compare the network features between the two groups.

RESULTS

In the network of cognitive function and OCD-related symptoms, nodes representing IQ, letter/number span test, accuracy of task switching test and obsession were much important in the network in terms of their larger strengths and edges. By constructing the networks of these two groups respectively, there was a strong similarity except that the symptom's network in healthy group had a higher degree of overall connectivity.

LIMITATIONS

Due to the small sample size, the stability of the network cannot be guaranteed. Due to the cross-sectional nature of the data, we were unable to determine how the cognitive-symptom network would change with disease deterioration or treatment.

CONCLUSIONS

The present study highlights the important role of variables such as obsession and IQ from a network perspective. These results deepen our understanding of the multivariate relationship between cognitive dysfunction and OCD symptoms, and may promote the prediction and diagnosis of OCD.

Physical fitness is associated with neural activity during working memory performance in major depressive disorder

BACKGROUND

Deficits in cognition like working memory (WM) are highly prevalent symptoms related to major depressive disorder (MDD). Neuroimaging studies have described frontoparietal abnormalities in patients with MDD as a basis for these deficits. Based on research in healthy adults, it is hypothesized that increased physical fitness might be a protective factor for these deficits in MDD. However, the relationship between physical fitness and WM-related neural activity and performance has not been tested in MDD, to date. Understanding these associations could inform the development of physical exercise interventions in MDD.

METHODS

Within a larger project, 111 (53female) MDD outpatients and 56 (34female) healthy controls performed an n-back task (0-, 1-, 2-, 3-back) during functional Magnetic Resonance Imaging. Physical fitness from a graded exercise test on a cycle ergometer was performed by 106 MDD patients.

RESULTS

Patients showed reduced performance particularly at high loads of the n-back WM task and prolonged reaction times at all n-back loads. A whole-brain interaction analysis of group by WM load revealed reduced neural activity in six frontoparietal clusters at medium and high WM loads in MDD patients compared to healthy controls. Analysis of covariance within the MDD sample showed that physical fitness was associated with neural activity in right and left superior parietal lobules. Externally defined Regions of Interest confirmed this analysis.

CONCLUSIONS

Results indicate frontoparietal hypoactivity in MDD at high demands, arguing for decreased WM capacity. We demonstrate a parietal fitness correlate which could be used to guide future research on effects of exercise on cognitive functioning in MDD.

Growth trajectories for executive and social cognitive abilities in an Indian population sample: Impact of demographic and psychosocial determinants

Cognitive abilities are markers of brain development and psychopathology. Abilities, across executive, and social domains need better characterization over development, including factors that influence developmental change. This study is based on the cVEDA [Consortium on Vulnerability to Externalizing Disorders and Addictions] study, an Indian population based developmental cohort. Verbal working memory, visuo-spatial working memory, response inhibition, set-shifting, and social cognition (faux pas recognition and emotion recognition) were cross-sectionally assessed in > 8000 individuals over the ages 6-23 years. There was adequate representation across sex, urban-rural background, psychosocial risk (psychopathology, childhood adversity and wealth index, i.e. socio-economic status). Quantile regression was used to model developmental change. Age-based trajectories were generated, along with examination of the impact of determinants (sex, childhood adversity, and wealth index). Development in both executive and social cognitive abilities continued into adulthood. Maturation and stabilization occurred in increasing order of complexity, from working memory to inhibitory control to cognitive flexibility. Age related change was more pronounced for low quantiles in response inhibition (β∼4 versus  -1 versus -0.25 for lower quantiles). Wealth index had the largest influence on developmental change across cognitive abilities. Sex differences were prominent in response inhibition, set-shifting and emotion recognition. Childhood adversity had a negative influence on cognitive development. These findings add to the limited literature on patterns and determinants of cognitive development. They have implications for understanding developmental vulnerabilities in young persons, and the need for providing conducive socio-economic environments.

Is cortical inhibition in primary motor cortex related to executive control?

Recent research using paired-pulse transcranial magnetic stimulation (TMS) has shown that the speed with which people can stop an action is linked to GABAergic inhibitory activity in the motor system. Specifically, a significant proportion of the variance in stop signal reaction time (SSRT; a widely used measure of inhibitory control) is accounted for by short-interval cortical inhibition (SICI). It is still unclear whether this relationship reflects a broader link between GABAergic processes and executive functions, or a specific link between GABAergic processes and motor stopping ability. The current study sought to replicate the correlation between SSRT and SICI while investigating whether this association generalises to other measures of inhibitory control and working memory, and to long-interval cortical inhibition (LICI). Participants completed a battery of inhibition (Stop-Signal, Stroop, Flanker) and working memory (n-back, Digit Span, and Operation Span) tasks. We replicated the correlation between SICI and SSRT but found no other correlations between behavioural measures of executive control and the two cortical measures of inhibition. These findings indicate that the relationship between SSRT and SICI is specific to a particular property of response inhibition and likely reflects the function of local inhibitory networks mediated by GABA_A.

Effects of a three-week executive control training on adaptation to task difficulty and emotional interference

Intact executive functions are characterized by flexible adaptation to task requirements, while these effects are reduced in internalizing disorders. Furthermore, as executive functions play an important role in emotion regulation, deficits in executive functions may contribute to symptom generation in psychological disorders through increased emotional interference. Thus, the present study investigated transfer effects of a three-week executive control training on adaptation to task difficulty and emotional interference in healthy participants (n = 24) to further explore the training's suitability for clinical application. To assess the adaptation to task difficulty, the proportion congruency effect on behavioral data (response times, error rates) and ERP measures (N2, CRN) was assessed in a flanker task with varying frequency of incompatible trials (25%, 75%). To quantify emotional interference, flanker stimuli were superimposed on neutral or negative pictures. Replicating previous results, the training increased interference control as indexed by decreased response times and errors rates, increased N2 amplitude and decreased CRN amplitude in incompatible trials after training. Proportion congruency effects were weaker than expected and not affected by the training intervention. The training lead to a shift in the time-point of emotional interference: before training negative pictures lead to a reduction in CRN amplitude, while after training this reduction was observed for the N2. This pattern illustrates that the training leads to a change in task processing mode from predominant response-related cognitive control to predominant stimulus-related cognitive control (N2), indicating a proactive processing mode.

The functional connectivity predictor of therapeutic effect of continuous theta burst stimulation on obsessive-compulsive disorder: A preliminary study

OBJECTIVE

To evaluate the efficacy of continuous theta burst stimulation (cTBS) on the bilateral supplementary motor area (SMA) among patients with obsessive-compulsive disorder (OCD) and to explore the potential predictors of cTBS outcome based on neuroimaging.

METHODS

29 OCD patients and 29 healthy controls (HCs) were enrolled in this pilot study. Twenty consecutive cTBS intervention targeting at bilateral SMA was applied. MRI scan was carried out before cTBS and 15 regions in the executive control and sensorimotor network were chosen and analyzed using MATLAB, DPABI, and SPM12.

RESULTS

11 out of 29 patients responded to cTBS (37.93%), and the clinical symptom of OCD patients was significantly relieved after receiving regular cTBS. Also, the FC between Cerebelum_Crus2_L and Frontal_Inf_Tri_L of OCD patients showed positive prognosis for the efficacy of cTBS, with the area under the curve (AUC) of 0.85 (95% confidence interval: 0.718-0.989, p = 0.002). None of the patients had any serious adverse event.

CONCLUSION

cTBS intervention on bilateral SMA can significantly improve the symptoms of medicated OCD patients with moderate severity. And the pretherapy FC could be a valuable potential predictor of the cTBS treatment outcome among OCD patients.

Application of graph theory across multiple frequency bands in drug-naïve obsessive-compulsive disorder with no comorbidity

Recently, graph theoretical analysis based on resting-state functional magnetic resonance imaging has provided a means of investigating the complex brain connectome in obsessive-compulsive disorder (OCD) patients. However, these studies have been restricted to spontaneous blood oxygen level-dependent (BOLD) signals with frequency bands between 0.01 and 0.08 Hz, and the parameters from graph theory across multiple frequency bands have seldom been studied. Here, we calculated global metrics (small-worldness, global efficiency and modularity) and nodal metrics (degree centrality, betweenness centrality, nodal clustering coefficient and shortest path) at four different frequency bands (slow-2 (0.199-0.25 Hz), slow-3 (0.074-0.198 Hz), slow-4 (0.027-0.073 Hz) and slow-5 (0.01-0.027 Hz), from 0.01 to 0.25 Hz) in seventy-three OCD patients and ninety healthy controls. The analyses were also calculated in traditional low-frequency bands (0.01-0.08 Hz) for reference. For the global metrics, the OCD patients showed increased small-worldness and modularity only in the slow-3 band. For the local metrics, we observed a frequency-dependent characteristic, with the main significant differences in regions including the right precentral gyrus, occipital region, right anterior cingulum cortex and fusiform cortex. Our results suggested frequency-specific abnormalities of the brain connectome in OCD and the future studies may need to consider different frequency bands when measuring spontaneous activity in the brain.

Neural Correlates of Executive Functioning in Anorexia Nervosa and Obsessive-Compulsive Disorder

Anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) are commonly reported to co-occur and present with overlapping symptomatology. Executive functioning difficulties have been implicated in both mental health conditions. However, studies directly comparing these functions in AN and OCD are extremely limited. This review provides a synthesis of behavioral and neuroimaging research examining executive functioning in AN and OCD to bridge this gap in knowledge. We outline the similarities and differences in behavioral and neuroimaging findings between AN and OCD, focusing on set shifting, working memory, response inhibition, and response monitoring. This review aims to facilitate understanding of transdiagnostic correlates of executive functioning and highlights important considerations for future research. We also discuss the importance of examining both behavioral and neural markers when studying transdiagnostic correlates of executive functions.

Resting state functional brain imaging in obsessive-compulsive disorder across genders

OBJECTIVES

Epidemiological and clinical gender differences in obsessive-compulsive disorder (OCD) have been reported; however, gender differences in brain functional connectivity and the relationship between resting brain functional imaging and clinical symptoms has not been studied in OCD.

METHODS

A total of 62 drug-naive patients with OCD (31 males, 31 females) and 60 healthy controls (HCs) (30 males, 30 females) matched for age, sex, and education underwent magnetic resonance imaging. Amplitude of low-frequency fluctuations (ALFF) over the whole brain and seed-based connectivity analyses were evaluated to examine the intrinsic cerebral activity of the subjects. Additionally, associations between functional connectivity and clinical features were analysed.

RESULTS

Compared to male OCD (mOCD) patients, female OCD (fOCD) patients showed higher ALFF values in the right parahippocampal gyrus. Compared to HCs, fOCD patients showed significantly decreased functional connectivity between the right parahippocampal gyrus and whole brain to the right posterior central gyrus/precentral gyrus/superior temporal gyrus/barycentric lobule and left anterior cuneus. Abnormal functional connectivity was negatively correlated with the Yale-Brown Obsessive-Compulsive Scale, Beck Depression Inventory-II, and Beck Anxiety Inventory total scores.

CONCLUSIONS

Our results suggest that the right parahippocampal gyrus, which is related to executive control and emotional regulation, may show gender differences in OCD.

Polygenic risk for obsessive-compulsive disorder (OCD) predicts brain response during working memory task in OCD, unaffected relatives, and healthy controls

Alterations in frontal and parietal neural activations during working memory task performance have been suggested as a candidate endophenotype of obsessive-compulsive disorder (OCD) in studies involving first-degree relatives. However, the direct link between genetic risk for OCD and neuro-functional alterations during working memory performance has not been investigated to date. Thus, the aim of the current functional magnetic resonance imaging (fMRI) study was to test the direct association between polygenic risk for OCD and neural activity during the performance of a numeric n-back task with four working memory load conditions in 128 participants, including patients with OCD, unaffected first-degree relatives of OCD patients, and healthy controls. Behavioral results show a significant performance deficit at high working memory load in both patients with OCD and first-degree relatives (p < 0.05). A whole-brain analysis of the fMRI data indicated decreased neural activity in bilateral inferior parietal lobule and dorsolateral prefrontal cortex in both patients and relatives. Most importantly, OCD polygenic risk scores predicted neural activity in orbitofrontal cortex. Results indicate that genetic risk for OCD can partly explain alterations in brain response during working memory performance, supporting the notion of a neuro-functional endophenotype for OCD.

Identifying regions in prefrontal cortex related to working memory improvement: A novel meta-analytic method using electric field modeling

Altering cortical activity using transcranial direct current stimulation (tDCS) has been shown to improve working memory (WM) performance. Due to large inter-experimental variability in the tDCS montage configuration and strength of induced electric fields, results have been mixed. Here, we present a novel meta-analytic method relating behavioral effect sizes to electric field strength to identify brain regions underlying largest tDCS-induced WM improvement. Simulations on 69 studies targeting left prefrontal cortex showed that tDCS electric field strength in lower dorsolateral prefrontal cortex (Brodmann area 45/47) relates most strongly to improved WM performance. This region explained 7.8 % of variance, equaling a medium effect. A similar region was identified when correlating WM performance and electric field strength of right prefrontal tDCS studies (n = 18). Maximum electric field strength of five previously used tDCS configurations were outside of this location. We thus propose a new tDCS montage which maximizes the tDCS electric field strength in that brain region. Our findings can benefit future tDCS studies that aim to affect WM function.

Effects of short-term cognitive-coping therapy on resting-state brain function in obsessive-compulsive disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) tends to be treatment refractory. Recently, cognitive-coping therapy (CCT) for OCD is reported to be an efficacious psychotherapy. However, the underlying neurophysiological mechanism remains unknown. Here, the effects of CCT on OCD and the resting-state brain function were investigated.

METHODS

Fifty-nine OCD patients underwent CCT, pharmacotherapy plus CCT (pCCT), or pharmacotherapy. Before and after a 4-week treatment, Yale-Brown obsessive-compulsive scale (Y-BOCS) was evaluated and resting-state functional magnetic resonance imaging (rs-fMRI) was scanned.

RESULTS

Compared with the baseline, significant reduction of Y-BOCS scores was found after four-week treatment (p < .001) in groups of CCT and pCCT, not in pharmacotherapy. Post-treatment Y-BOCS scores of CCT group and pCCT group were not different, but significantly lower than that of pharmacotherapy group (p < .001). Compared with pretreatment, two clusters of brain regions with significant change in amplitude of low-frequency fluctuation (ALFF) were obtained in those who treated with CCT and pCCT, but not in those who received pharmacotherapy. The ALFF in cluster 1 (insula, putamen, and postcentral gyrus in left cerebrum) was decreased, while the ALFF in cluster 2 (occipital medial gyrus, occipital inferior gyrus, and lingual gyrus in right hemisphere) was increased after treatment (corrected p < .05). The changes of ALFF were correlated with the reduction of Y-BOCS score and were greater in remission than in nonremission. The reduction of the fear of negative events was correlated to the changes of ALFF of clusters and the reduction of Y-BOCS score.

CONCLUSIONS

The effectiveness of CCT for OCD was related to the alteration of resting-state brain function-the brain plasticity.

TRIAL REGISTRATION

ChiCTR-IPC-15005969.

Response Inhibition, Cognitive Flexibility and Working Memory in Obsessive-Compulsive Disorder, Generalized Anxiety Disorder and Social Anxiety Disorder

This study analyzed response inhibition, cognitive flexibility and working memory in three groups of patients diagnosed with obsessive-compulsive disorder, social anxiety disorder and generalized anxiety disorder, considering some variables that may influence results (nonverbal reasoning, comorbidity, use of pharmacotherapy). Neuropsychological measures were completed using a computerized Wisconsin card sorting test, Stroop color word test, go/no-go task, digits and Corsi. Significant differences were obtained among groups in cognitive flexibility and working memory variables. The obsessive-compulsive disorder (OCD) group showed the worst results. The social anxiety disorder group obtained greater effect sizes in visuospatial memory. However, significant differences between groups in visuospatial memory were no longer present when nonverbal reasoning was controlled. Comorbidity influenced interference in the OCD and generalized anxiety disorder (GAD) groups. In addition, the executive functions were differently influenced by the level of obsessions and anxiety, and the use of pharmacotherapy. Study limitations include a non-random selection of participants, modest sample size and design type (cross-sectional). The OCD group showed the worst results in flexibility cognitive and verbal working memory. Comorbidity, use of pharmacotherapy and level anxiety and obsessions were variables influencing the performance of executive functions.

Executive Functioning and Clinical Variables in Patients with Obsessive-Compulsive Disorder

Background: Cognitive flexibility, response inhibition, and working memory are considered the main mechanisms responsible for executive control. This study examined differences in cognitive flexibility, inhibition, and working memory in patients with obsessive–compulsive disorder (OCD) relative to a control group. Method: A total of 62 obsessive-compulsive participants (OCD = 32; healthy control = 32) aged between 17 and 56 years old (M = 33.16, SD = 9.23) were administered the computerized Wisconsin Card Sorting Test, Stroop Color–Word Test, Go/No-Go Task, Digit Test, and Corsi Block Test. Clinician-rated and self-reported obsessive–compulsive symptom severity, and anxiety, depression, and obsessive beliefs were evaluated. Results: The control group performed better than the OCD group in tasks involving cognitive flexibility, inhibition, and visuospatial working memory. Anxiety and obsessive beliefs influenced the participants’ performance on inhibition and working memory tasks. Similarly, comorbidity also influenced inhibition and working memory. In addition, the use of pharmacotherapy and the degree of OCD symptom severity influenced verbal working memory. Conclusions: Cognitive flexibility, inhibition, and visuospatial working memory deficits may be endophenotypes of OCD but require further examination for specificity. OCD severity, comorbidity patterns, anxiety, and obsessive beliefs may influence performance.

Functional Brain Imaging and OCD

In the last 20 years, functional magnetic resonance imaging (fMRI) has been extensively used to investigate system-level abnormalities in the brain of patients with obsessive-compulsive disorder (OCD). In this chapter, we start by reviewing the studies assessing regional brain differences between patients with OCD and healthy controls in task-based fMRI. Specifically, we review studies on executive functioning and emotional processing, protocols in which these patients have been described to show alterations at the behavioral level, as well as research using symptom provocation protocols. Next, we review studies on brain connectivity alterations, focusing on resting-state studies evaluating disruptions in fronto-subcortical functional connectivity and in cortical networks. Likewise, we also review research on effective connectivity, which, different from functional connectivity, allows for ascertaining the directionality of inter-regional connectivity alterations. We conclude by reviewing the most significant findings on a topic of translational impact, such as the use of different fMRI measurements to predict response across a variety of treatment approaches. Overall, results suggest that there exists a pattern of regions, involving, but not limited to, different nodes of the cortico-striatal-thalamo-cortical circuits, showing robust evidence of functional alteration across studies, although the nature of the alterations critically depends on the specific tasks and their particular demands. Moreover, such findings have been, to date, poorly translated into clinical practice. It is suggested that this may be partially accounted for by the difficulty to integrate into a common framework results obtained under a wide variety of analysis approaches.

Altered Resting-State Brain Activity in Schizophrenia and Obsessive-Compulsive Disorder Compared With Non-psychiatric Controls: Commonalities and Distinctions Across Disorders

Backgrounds: Schizophrenia (SCZ) and obsessive-compulsive disorder (OCD) are classified as two chronic psychiatric disorders with high comorbidity rate and shared clinical symptoms. Abnormal spontaneous brain activity within the cortical-striatal neural circuits has been observed in both disorders. However, it is unclear if the common or distinct neural abnormalities underlie the neurobiological substrates in the resting state. Methods: Resting-state fMRI data were collected from 88 patients with SCZ, 58 patients with OCD, and 72 healthy control subjects. First, we examined differences in amplitude of low-frequency fluctuations (ALFF) among three groups. Resting-state functional connectivity (rsFC) analysis with the brain region that showed different ALFF as the seed was then conducted to identify the changes in brain networks. Finally, we examined the correlation between the altered activities and clinical symptoms. Results: Both the patients with SCZ and OCD showed increased ALFF in the right hippocampus and decreased ALFF in the left posterior cingulate cortex (PCC). SCZ patients exhibited increased ALFF in the left caudate [voxel-level family-wise error (FWE) P < 0.05] and decreased rsFC between the left caudate and right cerebellum, which correlated with positive symptoms. The left caudate showed increased rsFC with the right thalamus and bilateral supplementary motor complex (SMC) in OCD patients (cluster-level FWE P < 0.05). Conclusions: The hippocampus and PCC are common regions presenting abnormal local spontaneous neuronal activities in both SCZ and OCD, while the abnormality of the striatum can reflect the differences. Increased ALFF in the striatum and symptom-related weakened rsFC between the caudate and cerebellum showed SCZ specificity. Enhanced rsFC between the caudate and SMC may be a key characteristic in OCD. Our research shows the similarities and differences between the two diseases from the perspective of resting-state fMRI, which provides clues to understand the disease and find methods for treatment.

Disentangling Within- and Between-Person Effects During Response Inhibition in Obsessive-Compulsive Disorder

Background: Obsessive-compulsive disorder (OCD) has been related to worse performance, abnormal brain activity, and functional connectivity during response inhibition. Whether these findings are indications of stable traits that contribute to the development of the disorder, or whether they are a result of the state severity of obsessions and anxiety, remains unclear since previous research mainly has employed cross-sectional designs. The present study aimed to assess longitudinal between- and within-person relationships between symptoms, task performance, right inferior frontal gyrus brain activation, and connectivity between the right amygdala and the right pre-supplementary motor area in 29 OCD patients before and after concentrated exposure and response prevention treatment. Method: Patients received exposure and response prevention delivered during 4 consecutive days, following the Bergen 4-day Treatment format. Patients performed a Stop Signal Task during 3T functional Magnetic Resonance Imaging the day before treatment, as well as 1 week and 3 months after treatment completion. Multilevel models were used to analyze disaggregated within- and between-person effects over time. Independent variables were scores on the symptom severity scales for OCD, anxiety, depression, and state distress during scanning. Dependent variables were reaction time for go trials, stop signal response time, task-related brain activation and connectivity. Results: A positive between-person effect was found for obsessive-compulsive, anxiety, and depressive symptom severity on go trial reaction time, indicating that patients with higher symptom scores on average respond slower during accurate go trials. We also found no significant between- or within-person relations between symptom severity and task-related activation or fronto-limbic connectivity. Conclusions: The between-person findings may point toward a general association between slower processing speed and symptom severity in OCD. Longitudinal studies should disaggregate between- and within-person effects to better understand variation over time.

Correlations Between Working Memory Impairment and Neurometabolites of the Prefrontal Cortex in Drug-Naive Obsessive-Compulsive Disorder

PURPOSE

This study aimed to investigate the mechanism of working memory (WM) impairment in drug-naive obsessive-compulsive disorder (OCD) by using neuropsychological tests and proton magnetic resonance spectroscopy (¹H-MRS).

PATIENTS AND METHODS

A total of 55 patients with drug-naive OCD and 55 healthy controls (HCs) were recruited for this study. The working memory (WM) was evaluated using the digit span test (DST), visual space memory test (VSMT), and the 2-back task and stroop color word test (SCWT). The bilateral metabolite levels of the prefrontal cortex (PFC) were evaluated by 1H-MRS, then determined the ratios of N-acetyl aspartate (NAA), choline-containing compounds (Cho), and myo-inositol (MI) to creatine (Cr). The independent sample t-test was used to analyse the differences in WM performance and neurometabolite ratios. Multivariate linear regression analysis was performed to screen the influential factors of WM, with an introduction level of 0.05 and a rejection level of 0.10.

RESULTS

1) Patients with OCD performed significantly worse on DST (score), VSMT (score), 2-back task (accuracy rate), SCWT (execution time) when compared with HCs. 2) NAA/Cr and Cho/Cr in the left PFC (lPFC) and MI/Cr ratios in the bilateral PFC of OCD patients were significantly lower when compared to HCs. 3) For OCD patients, the NAA/Cr ratio in the lPFC was negatively correlated with the score of DST (forwards), the Cho/Cr ratio in the lPFC was positively correlated with the accuracy rate of 2-back task, and the MI/Cr ratio in the right PFC (rPFC) was positively correlated with the score of DST (forwards) and the accuracy rate of VSMT. We also found that the compulsive symptoms showed a positive correlation with MI/Cr ratio of the rPFC.

CONCLUSION

Drug-naive OCD patients have demonstrated WM impairments, including phonological loop, visual-spatial sketchpad and central executive system, and the WM impairments might be associated with hypometabolism in the PFC, especially the lPFC.

Hippocampal functional network: The mediating role between obsession and anxiety in adult patients with obsessive-compulsive disorder

OBJECTIVES

Anxiety is a very common symptom and closely related to obsessive-compulsive symptoms in obsessive-compulsive disorder (OCD). However, the association between anxiety and obsessive-compulsive symptoms at the hippocampus network level remains unclear.

METHODS

This study enrolled 42 patients with OCD and 42 healthy controls (HCs), who underwent resting-state functional magnetic resonance imaging (fMRI) and clinical evaluation. Multiple linear regression analysis was performed to investigate the behavioural significance and interactive effects of obsessive-compulsive and anxiety symptoms on the hippocampus functional connectivity (HFC). The mediation analysis model was used to explore whether the hippocampus functional connectivity (FC) network indirectly mediated the relationship between obsessive-compulsive symptoms and anxiety.

RESULTS

Results showed that the FCs with the cerebellum, middle temporal gyrus (MTG) and anterior cingulate gyrus (ACG) were increased in the hippocampus FC network in patients with OCD compared with those in HCs. The regions of interactive effects between anxiety and obsession, which are mainly located in the prefrontal cortex and MTG, were positively correlated. The mediation effect is 0.018 between obsession and anxiety on the HFC networks in patients with OCD.

CONCLUSIONS

The FC between the hippocampus and MTG plays a key role in the relationship between anxiety and obsession.

Stable inhibition-related inferior frontal hypoactivation and fronto-limbic hyperconnectivity in obsessive-compulsive disorder after concentrated exposure therapy

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Less IFG activation and more fronto-limbic connectivity was found in OCD.

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IFG hypoactivation and fronto-limbic hyperconnectivity persisted after exposure therapy.

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Activation and connectivity before treatment did not predict treatment outcome.

Response inhibition has previously been suggested as an endophenotype for obsessive–compulsive disorder (OCD), evidenced by studies showing worse task performance, and altered task-related activation and connectivity. However, it’s unclear if these measures change following treatment. In this study, 31 OCD patients and 28 healthy controls performed a stop signal task during 3 T functional magnetic resonance imaging before treatment, while 24 OCD patients and 17 healthy controls were rescanned one week and three months after concentrated exposure and response prevention over four consecutive days using Bergen 4-Day Format. To study changes over time we performed a longitudinal analysis on stop signal reaction time and task-related activation and amygdala connectivity during successful and failed inhibition. Results showed that there was no group difference in task performance. Before treatment, OCD patients compared to controls showed less inhibition-related activation in the right inferior frontal gyrus, and increased functional connectivity between the right amygdala and the right inferior frontal gyrus and pre-supplementary motor area. During error-processing, OCD patients versus controls showed less activation in the pre-SMA before treatment. These group differences did not change after treatment. Pre-treatment task performance, brain activation, and connectivity were unrelated to the degree of symptom improvement after treatment. In conclusion, inferior frontal gyrus hypoactivation and increased fronto-limbic connectivity are likely trait markers of OCD that remain after effective exposure therapy.

MRI-Based Multimodal Approach to the Assessment of Clinical Symptom Severity of Obsessive-Compulsive Disorder

OBJECTIVE

This study assessed the associations of the abnormal brain activation and functional connectivity (FC) during memory processing and brain volume alteration in conjunction with psychiatric symptom severity in patients with obsessive-compulsive disorder (OCD).

METHODS

Twenty-OCD patients and 20-healthy controls (HC) underwent T1-weighted and functional imaging underlying explicit memory task.

RESULTS

In memory encoding, OCD patients showed higher activities in right/left (Rt./Lt.) inferior temporal gyrus (ITG), medial prefrontal cortex (MPFC), dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC), compared with HC. In task-based FC, caudate (Cd) was positively connected with DLPFC and ITG in OCD, while HC showed different connectivities of Cd-ACC and Rt.-Lt. ITG. In memory retrieval, only Cd was activated in OCD patients. Cd was positively connected with DLPFC and vmPFC in OCD, but negatively connected between same brain areas in HC. OCD patients showed increased gray matter (GM) volumes of cerebellum, DLPFC, orbitofrontal cortex (OFC), hippocampus, Cd and ITG, and concurrently, increased white matter volumes of DLPFC. In OCD patients, GM volumes of Cd and OFC were positively correlated with HAMA and Y-BOCS. Functional activity changes of Cd in OCD were positively correlated with Y-BOCS.

CONCLUSION

Our findings support to accessing clinical symptom and its severity linked by brain structural deformation and functional abnormality in OCD patients.

Altered brain network topology related to working memory in internet addiction

BACKGROUND AND AIMS

The working memory (WM) ability of internet addicts and the topology underlying the WM processing in internet addiction (IA) are poorly understood. In this study, we employed a graph theoretical framework to characterize the topological properties of the IA brain network in the source cortical space during WM task.

METHODS

A sample of 24 subjects with IA and 23 matched healthy controls (HCs) performed visual 2-back task. Exact Low Resolution Electromagnetic Tomography was adopted to project the pre-processed EEG signals into source space. Subsequently, Lagged phase synchronization was calculated between all pairs of Brodmann areas, the graph theoretical approaches were then employed to estimate the brain topological properties of all participants during the WM task.

RESULTS

We found better WM behavioral performance in IA subjects compared with the HCs. Moreover, compared to the HC group, more integrated and hierarchical brain network was revealed in the IA subjects in alpha band. And altered regional centrality was mainly resided in frontal and limbic lobes. In addition, significant relationships between the IA severity and the significant altered graph indices were found.

CONCLUSIONS

In conclusion, these findings provide evidence to support the notion that altered topological configuration may underline changed WM function observed in IA.

Modality-specific overlaps in brain structure and function in obsessive-compulsive disorder: Multimodal meta-analysis of case-control MRI studies

Neuroimaging research has shown that patients with obsessive-compulsive disorder (OCD) may present brain structural and functional alterations, but the results across imaging modalities and task paradigms are difficult to reconcile. Are the same brain systems that are structurally different in OCD patients also involved in executive function and emotional processing? To answer this, we conducted separate meta-analyses of voxel-based morphometry studies, executive function functional magnetic resonance imaging (fMRI) studies, and emotional processing fMRI studies. Next, with a multimodal approach (conjunction analysis), we identified the common alterations across meta-analyses. Patients presented increased gray matter volume and hyperactivation in the putamen, but the putamen subregions affected differed depending on the psychological process. Left posterior/dorsal putamen showed hyperactivation during executive processing tasks, while predominantly right anterior/ventral putamen showed hyperactivation during emotional processing tasks. Interestingly, age was significantly associated with increased right putamen volume. Finally, the left dorsolateral prefrontal cortex was hyperactive in both functional domains. Our findings highlight task-specific correlates of brain structure and function in OCD and help integrate a growing literature.

The Place of Optical Coherence Tomography in Patients with Obsessive Compulsive Disorder

Objective

Optical coherence tomography (OCT) is an increasingly used new method that investigates changes in the retinal nerve fiber layer (RNFL) in neurodegenerative diseases. It provides high-resolution cross-sectional imaging of biological tissues. This study aimed to investigate the structural changes in RNFL in patients with obsessive compulsive disorder (OCD) using OCT and to investigate the possible effects of retinal function on the etiopathogenesis of OCD.

Materials and Methods

In this study, 30 patients diagnosed with OCD at the end of the Structured Clinical Interview for DSM (SCID-I), without any drug use status, and 31 healthy participants paired with the patients in terms of their sociodemographic characteristics were included. In the patient and control groups, the RNFL thickness was measured and compared at each locus using OCT.

Results

Statistically significant differences were found in RNFL, ganglion cell layer thickness, and central foveal thickness between the patients with OCD and the control group. In this study, the choroidal thickness values of the patient group were found to be higher than those of the control group; and a statistically significant difference was observed in the mean choroidal thickness values (p=0.045).

Conclusion

The findings of the study suggest that the RNFL thickness of patients with OCD does not decrease, but choroidal thickness may be an important biomarker to determine the etiopathogenesis of the disease and follow neurodegeneration.

Emotional interference under low versus high executive control

Previous research has demonstrated that task-irrelevant emotional distractors interfere with task performance especially under low phasic executive control (i.e., in nonconflict trials). In the present study, we measured medio-frontal ERPs (N2 and correct-related negativity, CRN) to elucidate which aspects of task performance are affected by emotional interference in a flanker task. To create emotional interference, negative and neutral pictures were presented during the flanker stimuli. N2 and CRN were reduced after negative pictures, indicating that conflict processing and performance monitoring are both affected by emotional interference. On the behavioral level, prolonged response times after negative pictures were observed under low phasic executive control (i.e., in compatible trials). Additionally, we explored whether emotional interference is modulated not only by phasic changes in executive control (i.e., conflict vs. nonconflict trials) but also by tonic changes in executive control (i.e., low vs. high overall conflict frequency). To this end, the flanker task consisted of two blocks with 25% versus 75% incompatible trials. Prolonged response times after negative pictures in compatible trials were observed only under low tonic executive control but not under high executive control.

Schizotypy and smooth pursuit eye movements as potential endophenotypes of obsessive-compulsive disorder

Patients with obsessive-compulsive disorder (OCD) show dysfunctions of the fronto-striatal circuitry, which imply corresponding oculomotor deficits including smooth pursuit eye movements (SPEM). However, evidence for a deficit in SPEM is inconclusive, with some studies reporting reduced velocity gain while others did not find any SPEM dysfunctions in OCD patients. Interestingly, psychosis-like traits have repeatedly been linked to both OCD and impaired SPEM. Here, we examined a large sample of n = 168 patients with OCD, n = 93 unaffected first-degree relatives and n = 171 healthy control subjects to investigate whether elevated levels of schizotypy and SPEM deficits represent potential endophenotypes of OCD. We applied a SPEM task with high demands on predictive pursuit that is more sensitive to assess executive dysfunctions than a standard task with continuous visual feedback, as episodes of target blanking put increased demands on basal ganglia and prefrontal involvement. Additionally, we examined the relation between schizotypy and SPEM performance in OCD patients and their relatives. Results indicate that OCD patients and unaffected relatives do not show deficient performance in either standard or predictive SPEM. Yet, both patients and relatives exhibited elevated levels of schizotypy, and schizotypy was significantly correlated with velocity gain during standard trials in unmedicated and depression-free OCD patients. These findings highlight the role of schizotypy as a candidate endophenotype of OCD and add to the growing evidence for predisposing personality traits in OCD. Furthermore, intact gain may represent a key characteristic that distinguishes the OCD and schizophrenia patient populations.

Neuroimaging findings in obsessive-compulsive disorder: A narrative review to elucidate neurobiological underpinnings

Obsessive compulsive disorder (OCD) is a common psychiatric illness and significant research has been ongoing to understand its neurobiological basis. Neuroimaging studies right from the 1980s have revealed significant differences between OCD patients and healthy controls. Initial imaging findings showing hyperactivity in the prefrontal cortex (mainly orbitofrontal cortex), anterior cingulate cortex and caudate nucleus led to the postulation of the cortico-striato-thalamo-cortical (CSTC) model for the neurobiology of OCD. However, in the last two decades emerging evidence suggests the involvement of widespread associative networks, including regions of the parietal cortex, limbic areas (including amygdala) and cerebellum. This narrative review discusses findings from structural [Magnetic Resonance Imaging (MRI), Diffusion Tensor Imaging(DTI)], functional [(functional MRI (fMRI), Single photon emission computed tomography (SPECT), Positron emission tomography (PET), functional near-infrared spectroscopy (fNIRS)], combined structural and functional imaging studies and meta-analyses. Subsequently, we collate these findings to describe the neurobiology of OCD including CSTC circuit, limbic system, parietal cortex, cerebellum, default mode network and salience network. In future, neuroimaging may emerge as a valuable tool for personalised medicine in OCD treatment.

Motor dysfunction as research domain across bipolar, obsessive-compulsive and neurodevelopmental disorders

Although genuine motor abnormalities (GMA) are frequently found in schizophrenia, they are also considered as an intrinsic feature of bipolar, obsessive-compulsive, and neurodevelopmental disorders with early onset such as autism, ADHD, and Tourette syndrome. Such transnosological observations strongly suggest a common neural pathophysiology. This systematic review highlights the evidence on GMA and their neuroanatomical substrates in bipolar, obsessive-compulsive, and neurodevelopmental disorders. The data lends support for a common pattern contributing to GMA expression in these diseases that seems to be related to cerebello-thalamo-cortical, fronto-parietal, and cortico-subcortical motor circuit dysfunction. The identified studies provide first evidence for a motor network dysfunction as a correlate of early neurodevelopmental deviance prior to clinical symptom expression. There are also first hints for a developmental risk factor model of these mental disorders. An in-depth analysis of motor networks and related patho-(physiological) mechanisms will not only help promoting Research Domain Criteria (RDoC) Motor System construct, but also facilitate the development of novel psychopharmacological models, as well as the identification of neurobiologically plausible target sites for non-invasive brain stimulation.