Association between hippocampus volume and symptom profiles in obsessive-compulsive disorder

Exploring the relationship between context and obsessions in individuals with obsessive-compulsive disorder symptoms: a narrative review

Obsessions in obsessive-compulsive disorder (OCD) have long been proposed to differ from intrusive thoughts in unaffected individuals based on appraisal of the thoughts. However, more recent research indicates that cognitive processes behind obsessions may differ significantly from those in healthy individuals concerning their contextual relationship. This narrative literature review summarizes current evidence for the role of context-relatedness for obsessions in OCD and intrusive thoughts in affected and unaffected individuals. The review encompasses a total of five studies, two of which include individuals diagnosed with OCD (one study also includes a group of unaffected control individuals), while the other three studies investigate the relationship between OCD symptoms and context in unaffected individuals. As assessed by mainly self-reports, the review examines the connection between thoughts and their context, shedding light on how the repetition and automaticity of thoughts, as well as their detachment from context over time contribute to defining obsessions in contrast to intrusive thoughts. However, the link with context depends on the content of the obsessions. We propose the term "decontextualization of thoughts" to describe the phenomenon that obsessions gradually lose their connection with external context during the development of OCD. Future research should investigate whether this hypothesis can be supported by experimental evidence and identify whether this shift might be more likely a cause or a consequence of the disorder.

Decreased intrinsic neural timescales in obsessive compulsive disorder and two distinct subtypes revealed by heterogeneity through discriminative analysis

BACKGROUND

OCD is featured as the destruction of information storage and processing. The cognition of neurobiological and clinical heterogeneity is in suspense and poorly studied.

METHODS

Ninety-nine patients and matched HCs(n = 104) were recruited and underwent resting-state functional MRI scans. We applied INT to evaluate altered local neural dynamics representing the ability of information integration. Moreover, considering OCD was a highly heterogeneous disorder, we investigated putative OCD subtypes from INT using a novel semi-supervised machine learning, named HYDRA.

RESULTS

Compared with HCs, patients with OCD showed decreased INTs in extensive brain regions, including bilateral cerebellum and precuneus, STG/MTG and PCC, hippocampus in DMN; right IFG/MFG/SFG, SPL and bilateral angular gyrus in CEN and insula, SMA in SN. Moreover, many other regions involved in visual processing also had disrupted dynamics of local neural organization, consisting of bilateral CUN, LING and fusiform gyrus and occipital lobe. HYDRA divided patients into two distinct neuroanatomical subtypes from INT. Subtype 1 showed decreased INTs in distributed networks, while subtype 2 presented increased in several common regions which were also found to be decreased in subtype 1, such as STG, IPL, postcentral gyrus and left insula, supramarginal gyrus.

CONCLUSION

This study showed distinct abnormalities from the perspective of dynamics of local neural organization in OCD. Such alteration and dimensional approach may provide a new insight into the prior traditional cognition of this disorder and to some extent do favor of more precise diagnosis and treatment response in the future.

Compulsive-like Behaviors in Amyloid-β 1-42-Induced Alzheimer's Disease in Mice Are Associated With Hippocampo-cortical Neural Circuit Dysfunction

Background

In addition to memory deficits, patients with Alzheimer's disease (AD) experience neuropsychiatric disturbances. Recent studies have suggested the association of obsessive-compulsive disorder with the early stages of AD. However, there is a lack of understanding of the neurobiological underpinnings of compulsive-like behaviors at the neuronal circuit level and their relationship with AD.

Methods

We have addressed this issue in an amyloid-β 1-42-induced mouse model of AD by studying compulsive-like behaviors. Next, we compared the hippocampal and medial prefrontal cortex (mPFC) local field potential pattern and coherence between these regions of control and AD mice. We also assessed the expression pattern of acetylcholine and glutamatergic signaling in these regions, using quantitative polymerase chain reaction.

Results

Our findings show that AD mice exhibit compulsive-like behaviors, as evidenced by enhanced marble burying, nest building, and burrowing. Furthermore, AD mice exhibited hippocampo-cortical circuit dysfunction demonstrated by decreased power of rhythmic oscillations at the theta (4-12 Hz) and gamma (25-50 Hz) frequencies in the hippocampus and mPFC, two functionally interconnected brain regions involved both in AD and compulsive behaviors. Importantly, coherence between the hippocampus and mPFC in the theta band of AD animals was significantly reduced. Furthermore, we found reduced cholinergic and glutamatergic neurotransmission in the hippocampus and mPFC of AD mice.

Conclusions

We conclude that the hippocampo-cortical functional alterations may play a significant role in mediating the compulsive-like behaviors observed in AD mice. These findings may help in understanding the underlying circuit mechanisms of obsessive-compulsive disorder-like phenotypes associated with AD.

Neuronal glutamate transporters control reciprocal inhibition and gain modulation in D1 medium spiny neurons

Understanding the function of glutamate transporters has broad implications for explaining how neurons integrate information and relay it through complex neuronal circuits. Most of what is currently known about glutamate transporters, specifically their ability to maintain glutamate homeostasis and limit glutamate diffusion away from the synaptic cleft, is based on studies of glial glutamate transporters. By contrast, little is known about the functional implications of neuronal glutamate transporters. The neuronal glutamate transporter EAAC1 is widely expressed throughout the brain, particularly in the striatum, the primary input nucleus of the basal ganglia, a region implicated with movement execution and reward. Here, we show that EAAC1 limits synaptic excitation onto a population of striatal medium spiny neurons identified for their expression of D1 dopamine receptors (D1-MSNs). In these cells, EAAC1 also contributes to strengthen lateral inhibition from other D1-MSNs. Together, these effects contribute to reduce the gain of the input-output relationship and increase the offset at increasing levels of synaptic inhibition in D1-MSNs. By reducing the sensitivity and dynamic range of action potential firing in D1-MSNs, EAAC1 limits the propensity of mice to rapidly switch between behaviors associated with different reward probabilities. Together, these findings shed light on some important molecular and cellular mechanisms implicated with behavior flexibility in mice.

Insulin and Disorders of Behavioural Flexibility

Behavioural inflexibility is a symptom of neuropsychiatric and neurodegenerative disorders such as Obsessive-Compulsive Disorder, Autism Spectrum Disorder and Alzheimer's Disease, encompassing the maintenance of a behaviour even when no longer appropriate. Recent evidence suggests that insulin signalling has roles apart from its regulation of peripheral metabolism and mediates behaviourally-relevant central nervous system (CNS) functions including behavioural flexibility. Indeed, insulin resistance is reported to generate anxious, perseverative phenotypes in animal models, with the Type 2 diabetes medication metformin proving to be beneficial for disorders including Alzheimer's Disease. Structural and functional neuroimaging studies of Type 2 diabetes patients have highlighted aberrant connectivity in regions governing salience detection, attention, inhibition and memory. As currently available therapeutic strategies feature high rates of resistance, there is an urgent need to better understand the complex aetiology of behaviour and develop improved therapeutics. In this review, we explore the circuitry underlying behavioural flexibility, changes in Type 2 diabetes, the role of insulin in CNS outcomes and mechanisms of insulin involvement across disorders of behavioural inflexibility.

Relationship between white matter alterations and contamination subgroup in obsessive compulsive disorder: A diffusion tensor imaging study

Approximately 2%-3% of the world population suffers from obsessive-compulsive disorder (OCD). Several brain regions have been involved in the pathophysiology of OCD, but brain volumes in OCD may vary depending on specific OCD symptom dimensions. The study aims to explore how white matter structure changes in particular OCD symptom dimensions. Prior studies attempt to find the correlation between Y-BOCS scores and OCD patients. However, in this study, we separated the contamination subgroup in OCD and compared directly to healthy control to find regions that exactly related to contamination symptoms. To evaluate structural alterations, diffusion tensor imaging was acquired from 30 OCD patients and 34 demographically matched healthy controls. Data were processed using tract-based spatial statistics (TBSS) analysis. First, by comparing all OCD to healthy controls, significant fractional anisotropy (FA) decreased in the right anterior thalamic radiation, right corticospinal tract, and forceps minor observed. Then by comparing the contamination subgroup to healthy control, FA decreases in the forceps minor region. Consequently, forceps minor plays a central role in the pathophysiology of contamination behaviors. Finally, other subgroups were compared to healthy control and discovered that FA in the right corticospinal tract and right anterior thalamic radiation is reduced.

Predicting responses to cognitive behavioral therapy in obsessive-compulsive disorder based on multilevel indices of rs-fMRI

OBJECTIVE

This study aimed to identify neuroimaging predictors to predict the response of cognitive behavioral therapy (CBT) in patients with obsessive-compulsive disorder (OCD) based on indices of resting-state functional magnetic resonance imaging (rs-fMRI).

METHODS

Fifty patients with OCD were enrolled and allocated to either high or low responder groups after CBT using a 50 % response rate as the delineator. The pre-treatment amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF), regional homogeneity (ReHo), and degree centrality (DC) in each cerebrum region, defined by automated anatomical labeling atlas, were extracted. Least absolute shrinkage and selection operator and logistic regression were used to select features and establish models.

RESULTS

The combination of multilevel rs-fMRI indices achieved the best performance, with a cross-validation area under the receiver operating characteristic curve (AUC) of 0.900. In this combined model, an increase of interquartile range (IQR) in fALFF of right inferior orbital frontal gyrus (IOFG), and ReHo of left hippocampus and superior occipital gyrus (SOG) corresponded to a 26.52 %, 38.67 % and 24.38 % increase in the possibility to be high responders of CBT, respectively. ALFF of left thalamus and ReHo of left putamen were negatively associated with the response to CBT, with a 14.30 % and 19.91 % decrease per IQR increase of the index value.

CONCLUSION

The combination of ALFF, fALFF and ReHo achieved a better predictive performance than separate index. Pre-treatment ALFF of the left thalamus, fALFF of the right IOFG, ReHo of the left hippocampus, SOG and putamen can be used as predictors of CBT response.

Associations of medication with subcortical morphology across the lifespan in OCD: Results from the international ENIGMA Consortium

BACKGROUND

Widely used psychotropic medications for obsessive-compulsive disorder (OCD) may change the volumes of subcortical brain structures, and differently in children vs. adults. We measured subcortical volumes cross-sectionally in patients finely stratified for age taking various common classes of OCD drugs.

METHODS

The ENIGMA-OCD consortium sample (1081 medicated/1159 unmedicated OCD patients and 2057 healthy controls aged 6-65) was divided into six successive 6-10-year age-groups. Individual structural MRIs were parcellated automatically using FreeSurfer into 8 regions-of-interest (ROIs). ROI volumes were compared between unmedicated and medicated patients and controls, and between patients taking serotonin reuptake inhibitors (SRIs), tricyclics (TCs), antipsychotics (APs), or benzodiazepines (BZs) and unmedicated patients.

RESULTS

Compared to unmedicated patients, volumes of accumbens, caudate, and/or putamen were lower in children aged 6-13 and adults aged 50-65 with OCD taking SRIs (Cohen's d = -0.24 to -0.74). Volumes of putamen, pallidum (d = 0.18-0.40), and ventricles (d = 0.31-0.66) were greater in patients aged 20-29 receiving APs. Hippocampal volumes were smaller in patients aged 20 and older taking TCs and/or BZs (d = -0.27 to -1.31).

CONCLUSIONS

Results suggest that TCs and BZs could potentially aggravate hippocampal atrophy of normal aging in older adults with OCD, whereas SRIs may reduce striatal volumes in young children and older adults. Similar to patients with psychotic disorders, OCD patients aged 20-29 may experience subcortical nuclear and ventricular hypertrophy in relation to APs. Although cross-sectional, present results suggest that commonly prescribed agents exert macroscopic effects on subcortical nuclei of unknown relation to therapeutic response.

Distinct clinical manifestations of obsessive-compulsive disorder are associated with cortical thickness alteration

BACKGROUND

Although brain structural changes have been reported in patients with obsessive-compulsive disorder (OCD), results from previous studies have been inconsistent. A growing number of studies have focused on obsessive beliefs and impulsivity which could be involved in the occurrence and maintenance of OCD symptoms. The present study aimed to examine whether there are distinct brain structural changes in patients with different OCD subgroups.

METHODS

Eighty-nine patients with OCD and 42 healthy controls were recruited to undergo structural magnetic resonance imaging brain scan. OCD patients were classified into subgroups according to scores of the Obsessive Belief Questionnaire (OBQ-44) and the Barratt Impulsiveness Scale (BIS-11) using cluster analysis. Group comparisons in cortical thickness and subcortical volumes between all OCD patients and healthy controls, as well as between subgroups of OCD patients and healthy controls, were carried out.

RESULTS

OCD patients with more obsessive beliefs and attentional impulsivity (OCD_OB_AT) had reduced cortical thickness at the inferior parietal gyrus, the superior and middle temporal gyrus and the insula compared with OCD patients with higher score on the non-planning impulsivity (OCD_NP, corrected p < 0.05). The whole group of OCD patients and both subgroups showed reduced cortical thickness at the superior parietal gyrus compared with controls (uncorrected p < 0.01, number of vertices > 100).

CONCLUSION

Our results suggest that apart from distinct phenomenology, there are distinct neural correlates of different OCD subgroups based on obsessive beliefs and impulsivity. These neural correlates may have clinical significance and should be considered in future research.

Increased functional connectivity between presupplementary motor area and inferior frontal gyrus associated with the ability of motor response inhibition in obsessive-compulsive disorder

Recent evidence suggests that presupplementary motor area (pre‐SMA) and inferior frontal gyrus (IFG) play an important role in response inhibition. However, no study has investigated the relationship between these brain networks at resting‐state and response inhibition in obsessive–compulsive disorder (OCD). We performed resting‐state functional magnetic resonance imaging scans and then measured the response inhibition of 41 medication‐free OCD patients and 49 healthy control (HC) participants by using the stop‐signal task outside the scanner. We explored the differences between OCD and HC groups in the functional connectivity of pre‐SMA and IFG associated with the ability of motor response inhibition. OCD patients showed a longer stop‐signal reaction time (SSRT). Compared to HC, OCD patients exhibit different associations between the ability of motor response inhibition and the functional connectivity between pre‐SMA and IFG, inferior parietal lobule, dorsal anterior cingulate cortex, insula, and anterior prefrontal cortex. Additional analysis to investigate the functional connectivity difference from the seed ROIs to the whole brain voxels revealed that, compared to HC, OCD exhibited greater functional connectivity between pre‐SMA and IFG. Also, this functional connectivity was positively correlated with the SSRT score. These results provide additional insight into the characteristics of the resting‐state functional connectivity of the regions belonging to the cortico‐striato‐thalamo‐cortical circuit and the cingulo‐opercular salience network, underlying the impaired motor response inhibition of OCD. In particular, we emphasize the importance of altered functional connectivity between pre‐SMA and IFG for the pathophysiology of motor response inhibition in OCD.

The effect of childhood trauma on the severity of obsessive-compulsive symptoms: A systematic review

BACKGROUND

Childhood trauma is associated with a range of psychiatric disorders, including obsessive-compulsive disorder (OCD). However, our understanding of the different types of childhood trauma and its impact on the different types and severity of obsessive-compulsive symptoms (OCS) is still in its infancy.

AIMS

We conducted a systematic review to synthesise the current knowledge on the possible relationships between childhood trauma and obsessive-compulsive symptoms in clinical and non-clinical populations.

METHODS

We systematically searched four electronic databases for studies reporting on childhood trauma and OCS severity. Subsequently, we qualitatively synthesised results of eligible studies and effect sizes were also calculated.

RESULTS

Twenty-four studies were included in this systematic review. Most studies used OCD samples (k = 16), with a few studies using a sample comprising of a range of psychiatric disorders (k = 6) and some studies using a general community sample (k = 2). Overall, there was support for a significant relationship between childhood trauma and OCS severity (8 out of 16 of the studies using OCD clinical samples, both studies using general population samples, and 5 out of 6 studies used mixed psychiatric samples).

CONCLUSIONS

We found evidence of a significant relationship between exposure to childhood trauma and OCS severity across clinical and non-clinical populations. Our results also suggest that a range rather than a single type of childhood trauma was associated with OCD.

Homogeneous grey matter patterns in patients with obsessive-compulsive disorder

BACKGROUND

Changes in grey matter volume have frequently been reported in patients with obsessive-compulsive disorder (OCD). Most studies performed whole brain or region-of-interest based analyses whereas grey matter volume based on structural covariance networks has barely been investigated up to now. Therefore, the present study investigated grey matter volume within structural covariance networks in a sample of 228 participants (n = 117 OCD patients, n = 111 healthy controls).

METHODS

First, an independent component analysis (ICA) was performed on all subjects' preprocessed T1 images to derive covariance-dependent morphometric networks. Then, grey matter volume from each of the ICA-derived morphometric networks was extracted and compared between the groups. In addition, we performed logistic regressions and receiver operating characteristic (ROC) analyses to investigate whether network-related grey matter volume could serve as a characteristic that allows to differentiate patients from healthy volunteers. Moreover, we assessed grey matter pattern organization by correlating grey matter volume in all networks across all participants. Finally, we explored a potential association between grey matter volume or whole-brain grey matter pattern organization and clinical characteristics in terms of symptom severity and duration of illness.

RESULTS

There were only subtle group differences in network-related grey matter volume. Network-related grey matter volume had moreover a very poor discrimination performance. We found, however, significant group differences with regard to grey matter pattern organization. When correlating grey matter volume in all networks across all participants, patients showed a significantly higher homogeneity across all networks and a significantly lower heterogeneity, as assessed by the coefficient of variation across all networks as well as in several single networks. There was no association with clinical characteristics.

CONCLUSION

The findings of the present study suggest that the pathological mechanisms of OCD reduce interindividual grey matter variability. We assume that common characteristics associated with the disorder may lead to a more uniform, disorder-specific morphometry.

Higher volumes of hippocampal subfields in pediatric obsessive-compulsive disorder

Differences in hippocampus volume have been identified in adult patients with obsessive-compulsive disorder (OCD). However, the role of this limbic structure in pediatric patients is unclear. This study aimed to investigate the hippocampus and its subregions in a sample of 29 children and adolescents with OCD compared to 28 healthy controls, matched for age, sex, education, and IQ. Volumetric segmentation was performed using the Freesurfer software to calculate the volumes of the subregions that reflect the hippocampal cytoarchitecture. The volumes of three anatomic subregions (tail, body, and head) were also calculated. ANCOVA was performed to investigate differences of these volumes between patients and controls, controlling for total gray matter volume. After Bonferroni correction for multiple comparisons (p-value < 0.00556 for the body and < 0.00625 for the head structures), patients presented statistically significant larger volumes of the following structures: left subiculum body; left CA4 body; left GC-DG body; left molecular layer body; right parasubiculum; left CA4 head; left molecular layer head; right subiculum head and right molecular layer head. These enlarged volumes resulted in larger left and right whole hippocampi in patients, as well as bilateral hippocampal heads and left hippocampal body (all p-values < 0.00625). There were no associations between OCD severity and hippocampal volumes. These findings diverge from previous reports on adults and may indicate that larger hippocampal volumes could reflect an early marker of OCD, not present in adults.

Plasticity-Related Activity in the Hippocampus, Anterior Cingulate, Orbitofrontal, and Prefrontal Cortex Following a Repeated Treatment with D2/D3 Agonist Quinpirole

Quinpirole (QNP) sensitization is a well-established model of stereotypical checking relevant to obsessive-compulsive disorder. Previously, we found that QNP-treated rats display deficits in hippocampus-dependent tasks. The present study explores the expression of immediate early genes (IEG) during QNP-induced stereotypical checking in the hippocampus, anterior cingulate cortex (ACC), orbitofrontal cortex (OFC), and medial prefrontal cortex (mPFC). Adult male rats were injected with QNP (0.5 mg/mL/kg; n = 15) or saline (n = 14) daily for 10 days and exposed to an arena enriched with two objects. Visits to the objects and the corners of the arena were recorded. QNP-treated rats developed an idiosyncratic pattern of visits that persisted across experimental days. On day 11, rats were exposed to the arena twice for 5 min and sacrificed. The expression of IEGs Arc and Homer1a was determined using cellular compartment analysis of temporal activity by fluorescence in situ hybridization. IEG-positive nuclei were counted in the CA1 area of the hippocampus, ACC, OFC, and mPFC. We found significantly fewer IEG-positive nuclei in the CA1 in QNP-treated rats compared to controls. The overlap between IEG expressing neurons was comparable between the groups. We did not observe significant differences in IEG expression between QNP treated and control rats in ACC, OFC, and mPFC. In conclusion, treatment of rats with quinpirole decreases plasticity-related activity in the hippocampus during stereotypical checking.

Sex differences in the association between obsessive-compulsive symptom dimensions and diurnal cortisol patterns

Previous studies in non-clinical populations suggest that obsessive-compulsive symptoms are associated with hypothalamic-pituitary-adrenal (HPA) axis measures and that there are sex differences in these associations. We aimed to replicate these findings in a sample of 57 patients with obsessive-compulsive disorder (OCD) and 98 healthy subjects. Current and lifetime OCD symptom dimensions were assessed with the Dimensional Yale-Brown Obsessive Compulsive Scale (DY-BOCS). Depressive symptoms and state and trait anxiety were also assessed. The following HPA axis measures were analysed in saliva: the diurnal cortisol slope (calculated using two formulas: [1] awakening to 11 p.m. [AWE diurnal slope] and [2] considering fixed time points [FTP diurnal slope] from 10 a.m. to 11 p.m.) and the dexamethasone suppression test ratio (DSTR) after 0.25 mg of dexamethasone. Multiple linear regression analyses were conducted to explore the contribution of OCD symptom dimensions to each HPA axis measure while adjusting for age, sex, BMI, smoking, trait anxiety and depressive symptoms. A sex-specific association between current ordering/symmetry symptoms and AWE diurnal cortisol slope (positive association [flattened slope] in men, inverse association [stepper slope] in women) was found. Two similar sex by OCD dimensions interactions were found for lifetime aggressive and ordering/symmetry symptoms and both (FTP, AWE) diurnal cortisol slopes. Current and lifetime hoarding symptoms were associated to a more flattened FTP diurnal cortisol slope in women. The DSTR was not associated with OCD symptoms. The lifetime interference in functionality was associated with a more flattened AWE diurnal cortisol slope. In conclusion, our study suggests that there are sex differences in the association between OCD subtypes and specific HPA axis measures.

Abnormal cortisol awakening responses in patients with neurotic and personality disorders admitted for psychotherapy in day hospital

Dysregulation of the hypothalamic-pituitary-adrenal axis (HPA axis) has been associated with various psychiatric conditions. The most interesting parameter of the HPA axis function is cortisol awakening response (CAR). Few data exist about the CAR in anxiety or personality disorders and findings are often contradictory showing blunted or increased CAR compared with control groups. The goal of this study was to determine whether patients with neurotic and personality disorders show a specific CAR pattern. The study population comprised 130 patients, mainly females (71.5%), with the primary diagnosis of a neurotic disorder or personality disorder according to ICD-10 admitted for psychotherapy in a day hospital. Pre-treatment cortisol levels were measured in three saliva samples collected in one day. The Symptom Checklist "O" and MMPI-2 were used to assess the pre-treatment levels of patients' symptoms and personality traits. The study revealed a high percentage of CAR non-responders (cortisol increase of less than 2.5 nmol/l) in the study group (43.1%), particularly in females. 49% of them were CAR non-responders compared with 28% in males and 25% in the general population, respectively. CAR non-responders did not differ from the remainder in clinical characteristics. Four different CAR patterns were found in the study group: negative (26.9%), blunted (26.1%), normal (25.4%) and elevated (21.6%) as well as a particular type was not related to clinical characteristics of the patients. The study suggests that abnormal CAR types are observed in patients with neurotic and personality disorders and further research into the mechanism of the findings is required.

Pseudo-continuous arterial spin labeling MRI study of patients with obsessive-compulsive disorder

Arterial spin labeling (ASL) magnetic resonance imaging is a novel technique that can measure regional cerebral blood flow (rCBF). Here we used pseudo-continuous ASL (pCASL) to examine the structural and functional imaging data in patients with obsessive-compulsive disorder (OCD). We estimated the gray matter volume imaging and pCASL imaging data by means of a voxel-by-voxel statistical analysis. We evaluated the differences of rCBF and gray matter volume between the OCD patients and healthy subjects. We detected a significant rCBF reduction in OCD patients in the right posterior cingulate extending to the lingual gyrus, thalamus, and hippocampus, and a significant increase in the left temporal gyrus and left frontal white matter region, compared with healthy subjects. We also observed a significant reduction in gray matter volume of OCD patients in the right hippocampus. We also estimated the correlation between the clinical severity of OCD and the rCBF and gray matter volumes, and found significant negative correlations between the severity of illness and the regional gray matter volume in the bilateral anterior cingulate corti. Our study demonstrated significant changes of rCBF in the cortico-striato-thalamo-cortical pathway around the hippocampus in OCD patients. These findings may help to elucidate the pathogenesis of OCD.

Hippocampal Volume in Provisional Tic Disorder Predicts Tic Severity at 12-Month Follow-up

Previous studies have investigated differences in the volumes of subcortical structures (e.g., caudate nucleus, putamen, thalamus, amygdala, and hippocampus) between individuals with and without Tourette syndrome (TS), as well as the relationships between these volumes and tic symptom severity. These volumes may also predict clinical outcome in Provisional Tic Disorder (PTD), but that hypothesis has never been tested. This study aimed to examine whether the volumes of subcortical structures measured shortly after tic onset can predict tic symptom severity at one-year post-tic onset, when TS can first be diagnosed. We obtained T1-weighted structural MRI scans from 41 children with PTD (25 with prospective motion correction (vNavs)) whose tics had begun less than 9 months (mean 4.04 months) prior to the first study visit (baseline). We re-examined them at the 12-month anniversary of their first tic (follow-up), assessing tic severity using the Yale Global Tic Severity Scale. We quantified the volumes of subcortical structures using volBrain software. Baseline hippocampal volume was correlated with tic severity at the 12-month follow-up, with a larger hippocampus at baseline predicting worse tic severity at follow-up. The volumes of other subcortical structures did not significantly predict tic severity at follow-up. Hippocampal volume may be an important marker in predicting prognosis in Provisional Tic Disorder.

Looking into the genetic bases of OCD dimensions: a pilot genome-wide association study

The multidimensional nature of obsessive-compulsive disorder (OCD) has been consistently reported. Clinical and biological characteristics have been associated with OCD dimensions in different ways. Studies suggest the existence of specific genetic bases for the different OCD dimensions. In this study, we analyze the genomic markers, genes, gene ontology and biological pathways associated with the presence of aggressive/checking, symmetry/order, contamination/cleaning, hoarding, and sexual/religious symptoms, as assessed via the Dimensional Yale-Brown Obsessive Compulsive Scale (DY-BOCS) in 399 probands. Logistic regression analyses were performed at the single-nucleotide polymorphism (SNP) level. Gene-based and enrichment analyses were carried out for common (SNPs) and rare variants. No SNP was associated with any dimension at a genome-wide level (p < 5 × 10^-8). Gene-based analyses showed one gene to be associated with hoarding (SETD3, p = 1.89 × 10^-08); a gene highly expressed in the brain and which plays a role in apoptotic processes and transcriptomic changes, and another gene associated with aggressive symptoms (CPE; p = 4.42 × 10^-6), which is involved in neurotrophic functions and the synthesis of peptide hormones and neurotransmitters. Different pathways or biological processes were represented by genes associated with aggressive (zinc ion response and lipid metabolism), order (lipid metabolism), sexual/religious (G protein-mediated processes) and hoarding (metabolic processes and anion transport) symptoms after FDR correction; while no pathway was associated with contamination. Specific genomic bases were found for each dimension assessed, especially in the enrichment analyses. Further research with larger samples and different techniques, such as next-generation sequencing, are needed to better understand the differential genetics of OCD dimensions.

Obsessive-Compulsive Symptoms in Obsessive-Compulsive Disorder and in Generalized Anxiety Disorder: Occurrence and Correlations

OBJECTIVE

Because of the heterogeneity of obsessive-compulsive disorders (OCDs) and their co-occurrence with anxiety disorders, we investigated the prevalence, severity, and correlations between obsessive and compulsive symptoms reported by patients diagnosed with OCD or generalized anxiety disorder (GAD).

METHODS

A retrospective study was conducted in 2 groups of patients: 76 patients diagnosed with OCD [F42 according to the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10)], and 186 patients diagnosed with GAD (F41.1 according to ICD-10), who had presented for therapy at the day ward. The Symptom Questionnaire "O," based on the Symptom Checklist 90-Revised (SCL-90-R) questionnaire, was used to assess obsessive, compulsive, and anxiety symptoms. The analysis took into account the impact of sex and the presence or absence of cognitive dysfunction (as assessed using the Bender Benton Visual Retention and Bender-Gestalt tests) on the associations being investigated.

RESULTS

We observed that obsessive and compulsive symptoms were more prevalent and more strongly expressed in the group with OCD than in the group with GAD. However, almost all patients with GAD (94%) confirmed the presence of some obsessive-compulsive symptoms. The study revealed differences in correlations with obsessions and compulsions between the OCD and GAD groups. In the group with OCD, no significant correlation between the severity of obsessions and compulsions was identified, whereas in the group with GAD, a significant positive correlation was found between the severity of those symptoms. In both the GAD and OCD groups, a greater intensity of obsessive-compulsive symptoms was accompanied by an increase in the severity of anxiety symptoms (with this effect noted to a greater extent with obsessions than compulsions).

CONCLUSIONS

The study revealed that patients with GAD often have coexisting obsessive-compulsive symptoms, which may not be identified during routine psychiatric examination. Obsessive-compulsive symptoms observed in patients with GAD may show a different structure than obsessive-compulsive symptoms in patients with OCD. The results of this study suggest that compulsions are more specific for the diagnosis of OCD than obsessions. Compulsions, such as counting related to the need for order and symmetry, may be associated with some cognitive dysfunctions and male sex, a finding that requires further research.

Maintained Visual-, Auditory-, and Multisensory-Guided Associative Learning Functions in Children With Obsessive-Compulsive Disorder

Sensory-guided acquired equivalence learning, a specific kind of non-verbal associative learning, is associated with the frontal cortex-basal ganglia loops and hippocampi, which seem to be involved in the pathogenesis of obsessive-compulsive disorder (OCD). In this study, we asked whether visual-, auditory-, and multisensory-guided associative acquired equivalence learning is affected in children with OCD. The first part of the applied learning paradigm investigated association building between two different sensory stimuli (where feedback was given about the correctness of the choices), a task that critically depends upon the basal ganglia. During the test phases, which primarily depended upon the hippocampi, the earlier learned and hitherto not shown but predictable associations were asked about without feedback. This study involved 31 children diagnosed with OCD according to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-V) criteria and 31 matched healthy control participants. The children suffering from OCD had the same performance as the control children in all phases of the applied visual-, auditory-, and multisensory-guided associative learning paradigms. Thus, both the acquisition and test phases were not negatively affected by OCD. The reaction times did not differ between the two groups, and the applied medication had no effect on the performances of the OCD patients. Our results support the findings that the structural changes of basal ganglia and hippocampi detected in adult OCD patients are not as pronounced in children, which could be the explanation of the maintained associative equivalence learning functions in children suffering from OCD.

Sex-specific association between the cortisol awakening response and obsessive-compulsive symptoms in healthy individuals

Background

Previous studies have shown associations between obsessive-compulsive disorder (OCD) and hypothalamic-pituitary-adrenal axis activity (HPA). We aimed to investigate the association between obsessive-compulsive (OC) symptoms and HPA axis functionality in a non-clinical sample and to explore whether there are sex differences in this relationship.

Methods

One hundred eighty-three healthy individuals without any psychiatric diagnosis (80 men, 103 women; mean age 41.3 ± 17.9 years) were recruited from the general population. The Obsessive-Compulsive Inventory Revised (OCI-R) was used to assess OC symptoms. State-trait anxiety, perceived stress, and stressful life events were also assessed. Saliva cortisol levels were determined at 6 time points (awakening, 30 and 60 min post-awakening, 10:00 a.m., 23:00 p.m. and 10:00 a.m. the following day of 0.25 mg dexamethasone intake [that occurred at 23:00 p.m.]). Three HPA axis measures were calculated: cortisol awakening response (CAR), cortisol diurnal slope, and cortisol suppression ratio after dexamethasone (DSTR). Multiple linear regression analyses were used to explore the association between OC symptoms and HPA axis measures while adjusting for covariates. Our main analyses were focused on OCI-R total score, but we also explored associations with specific OC symptom dimensions.

Results

No significant differences were observed between males and females in OC symptoms, anxiety measures, stress, or cortisol measures. In the multiple linear regression analyses between overall OC symptoms and HPA axis measures, a female sex by OC symptoms significant interaction (standardized beta = − 0.322; p = 0.023) for the CAR (but not cortisol diurnal slope nor DSTR) was found. Regarding specific symptom dimensions, two other sex interactions were found: a blunted CAR was associated with obsessing symptoms in women, whereas a more flattened diurnal cortisol slope was associated with ordering symptoms in men.

Conclusions

There are sex differences in the association between OC symptoms and HPA axis measures in healthy individuals.

Persistence of value-modulated attentional capture is associated with risky alcohol use

BACKGROUND

This study examined how risky patterns of alcohol use might be related to the persistence of learned attentional capture during reversal of stimulus-reward contingencies.

METHODS

Participants were 122 healthy adults (mean age 21 years, 66% female) who completed an assessment including a visual search task to measure value-modulated attentional capture, with a reversal phase following a period of initial training. The assessment also included questions about alcohol use.

RESULTS

Overall, attentional capture was greater for distractors associated with high reward than for those associated with low reward, replicating previous findings of value-modulated attentional capture. When stimulus-reward contingencies were reversed, a higher persistence of learned attentional capture was associated with risky patterns of alcohol use.

CONCLUSION

This result highlights how value-modulated attentional capture may persist and is associated with risky alcohol use in a non-clinical sample. Future research (potentially with clinical samples of heavy drinkers) aimed towards understanding the mechanisms that drive these reversal deficits, and their relation to other compulsive behaviours, may provide important insights into the development and maintenance of addictive behaviours.

Fluvoxamine combination therapy with tropisetron for obsessive-compulsive disorder patients: A placebo-controlled, randomized clinical trial

BACKGROUND

About 50% of obsessive-compulsive disorder patients still suffer significant symptoms even after the recommended first-line therapy. This demonstrates the necessity to investigate strategies to improve alleviation of symptoms.

OBJECTIVE

The main objective of this study was to investigate the efficacy of a 5-hydroxytryptophan 3 receptor antagonist, tropisetron, as an adjuvant therapy to selective serotonin reuptake inhibitors, in ameliorating obsessive-compulsive disorder symptoms.

METHODS

Men and women between the ages of 18-60 years diagnosed with obsessive-compulsive disorder, based on DSM5, who had a Yale-Brown obsessive compulsive scale score of more than 21 were recruited in a double-blinded, parallel-group, placebo-controlled, clinical trial of 10 weeks to receive either tropisetron (5 mg twice daily) and fluvoxamine (100 mg daily initially followed by 200 mg daily after week 4) or placebo and fluvoxamine. The primary outcome of interest in this study was the Yale-Brown obsessive compulsive scale total score decrease from baseline.

RESULTS

One hundred and eight participants were equally randomized into two groups; 48 participants in each group finished the trial. The Yale-Brown obsessive compulsive total score significantly dropped in both groups while the tropisetron group participants experienced a significantly higher decrease in their scores (Greenhouse-Geisser F(1.53-65.87)=3.516, p-value=0.04). No major adverse effect was observed in any of the groups.

CONCLUSION

This trial showed a significant efficacy for tropisetron over placebo in treatment of obsessive-compulsive disorder symptoms when added to fluvoxamine.

The Bed Nucleus of the Stria Terminalis, Homeostatic Satiety, and Compulsions: What Can We Learn From Polydipsia?

A compulsive phenotype characterizes several neuropsychiatric illnesses - including but not limited to - schizophrenia and obsessive compulsive disorder. Because of its perceived etiological heterogeneity, it is challenging to disentangle the specific neurophysiology that precipitates compulsive behaving. Using polydipsia (or non-regulatory water drinking), we describe candidate neural substrates of compulsivity. We further postulate that aberrant neuroplasticity within cortically projecting structures [i.e., the bed nucleus of the stria terminalis (BNST)] and circuits that encode homeostatic emotions (thirst, hunger, satiety, etc.) underlie compulsive drinking. By transducing an inaccurate signal that fails to represent true homeostatic state, cortical structures cannot select appropriate and adaptive actions. Additionally, augmented dopamine (DA) reactivity in striatal projections to and from the frontal cortex contribute to aberrant homeostatic signal propagation that ultimately biases cortex-dependent behavioral selection. Responding becomes rigid and corresponds with both erroneous, inflexible encoding in both bottom-up structures and in top-down pathways. How aberrant neuroplasticity in circuits that encode homeostatic emotion result in the genesis and maintenance of compulsive behaviors needs further investigation.