Assessing harmonized intelligence measures in a multinational study.

Studies examining the neurocognitive and circuit-based etiology of psychiatric illness are moving toward inclusive, global designs. A potential confounding effect of these associations is general intelligence; however, an internationally validated, harmonized intelligence quotient (IQ) measure is not available. We describe the procedures used to measure IQ across a five-site, multinational study and demonstrate the harmonized measure's cross-site validity. Culturally appropriate intelligence measures were selected: four short-form Wechsler intelligence tests (Brazil, Netherlands, South Africa, United States) and the Binet Kamat (India). Analyses included IQ scores from 255 healthy participants (age 18-50; 42% male). Regression analyses tested between-site differences in IQ scores, as well as expected associations with sociodemographic factors (sex, socioeconomic status, education) to assess validity. Harmonization (e.g., a priori selection of tests) yielded the compatibility of IQ measures. Higher IQ was associated with higher socioeconomic status, suggesting good convergent validity. No association was found between sex and IQ at any site, suggesting good discriminant validity. Associations between higher IQ and higher years of education were found at all sites except the United States. Harmonized IQ scores provide a measure of IQ with evidence of good validity that can be used in neurocognitive and circuit-based studies to control for intelligence across global sites.

White matter diffusion estimates in obsessive-compulsive disorder across 1653 individuals: machine learning findings from the ENIGMA OCD Working Group.

White matter pathways, typically studied with diffusion tensor imaging (DTI), have been implicated in the neurobiology of obsessive-compulsive disorder (OCD). However, due to limited sample sizes and the predominance of single-site studies, the generalizability of OCD classification based on diffusion white matter estimates remains unclear. Here, we tested classification accuracy using the largest OCD DTI dataset to date, involving 1336 adult participants (690 OCD patients and 646 healthy controls) and 317 pediatric participants (175 OCD patients and 142 healthy controls) from 18 international sites within the ENIGMA OCD Working Group. We used an automatic machine learning pipeline (with feature engineering and selection, and model optimization) and examined the cross-site generalizability of the OCD classification models using leave-one-site-out cross-validation. Our models showed low-to-moderate accuracy in classifying (1) "OCD vs. healthy controls" (Adults, receiver operator characteristic-area under the curve = 57.19 ± 3.47 in the replication set; Children, 59.8 ± 7.39), (2) "unmedicated OCD vs. healthy controls" (Adults, 62.67 ± 3.84; Children, 48.51 ± 10.14), and (3) "medicated OCD vs. unmedicated OCD" (Adults, 76.72 ± 3.97; Children, 72.45 ± 8.87). There was significant site variability in model performance (cross-validated ROC AUC ranges 51.6-79.1 in adults; 35.9-63.2 in children). Machine learning interpretation showed that diffusivity measures of the corpus callosum, internal capsule, and posterior thalamic radiation contributed to the classification of OCD from HC. The classification performance appeared greater than the model trained on grey matter morphometry in the prior ENIGMA OCD study (our study includes subsamples from the morphometry study). Taken together, this study points to the meaningful multivariate patterns of white matter features relevant to the neurobiology of OCD, but with low-to-moderate classification accuracy. The OCD classification performance may be constrained by site variability and medication effects on the white matter integrity, indicating room for improvement for future research.

Impact of the COVID-19 Pandemic on the symptomatology and routine of medicated patients with Obsessive-Compulsive Disorder.

OBJECTIVES: To study the COVID-19 impact on the routine of patients with obsessive-compulsive disorder (OCD) and putative changes in their symptoms and suicidal-related behavior, mainly in those with cleaning symptoms. METHODS: This was a cross-sectional study in which 58 patients completed an online self-report questionnaire comprising: the Obsessive-Compulsive Inventory-Revised (OCI-R); Coronavirus Stress and Traumatic Events Scale (COROTRAS); Coronavirus Health Impact Survey (CRISIS); Beck Anxiety and Beck Depression Inventories; and suicide-related behaviors questionnaire. Specifically regarding the last three measures, comparisons with another pre-pandemic sample (n=524) were performed. RESULTS: During the pandemic, patients spent more days inside their homes (x²=33.39, p-value=0.007), changed their patterns of alcohol consumption (x²=87.6, p-value < 0.001), and increased usage of social media (x²=68.83, p-value < 0.001). Participants with cleaning symptoms did not significantly differ from those without it in relation to stress, anxiety/depressive symptoms, and suicidal-related behaviors. Finally, our sample did not differ from an equivalent OCD sample assessed before the pandemic in terms of anxiety and depressive symptom severity, and suicidal-related behaviors. CONCLUSION: Overall, patients with OCD did not show changes in their lifestyle associated with higher stress levels during the pandemic. Patients with and without cleaning symptoms and patients before and during the pandemic also presented similar results.

Age of onset of obsessive-compulsive disorder differentially affects white matter microstructure.

Previous diffusion MRI studies have reported mixed findings on white matter microstructure alterations in obsessive-compulsive disorder (OCD), likely due to variation in demographic and clinical characteristics, scanning methods, and underpowered samples. The OCD global study was created across five international sites to overcome these challenges by harmonizing data collection to identify consistent brain signatures of OCD that are reproducible and generalizable. Single-shell diffusion measures (e.g., fractional anisotropy), multi-shell Neurite Orientation Dispersion and Density Imaging (NODDI) and fixel-based measures, were extracted from skeletonized white matter tracts in 260 medication-free adults with OCD and 252 healthy controls. We additionally performed structural connectome analysis. We compared cases with controls and cases with early (<18) versus late (18+) OCD onset using mixed-model and Bayesian multilevel analysis. Compared with healthy controls, adult OCD individuals showed higher fiber density in the sagittal stratum (B[SE] = 0.10[0.05], P = 0.04) and credible evidence for higher fiber density in several other tracts. When comparing early (n = 145) and late-onset (n = 114) cases, converging evidence showed lower integrity of the posterior thalamic radiation -particularly radial diffusivity (B[SE] = 0.28[0.12], P = 0.03)-and lower global efficiency of the structural connectome (B[SE] = 15.3[6.6], P = 0.03) in late-onset cases. Post-hoc analyses indicated divergent direction of effects of the two OCD groups compared to healthy controls. Age of OCD onset differentially affects the integrity of thalamo-parietal/occipital tracts and the efficiency of the structural brain network. These results lend further support for the role of the thalamus and its afferent fibers and visual attentional processes in the pathophysiology of OCD.

The functional connectome in obsessive-compulsive disorder: resting-state mega-analysis and machine learning classification for the ENIGMA-OCD consortium.

Current knowledge about functional connectivity in obsessive-compulsive disorder (OCD) is based on small-scale studies, limiting the generalizability of results. Moreover, the majority of studies have focused only on predefined regions or functional networks rather than connectivity throughout the entire brain. Here, we investigated differences in resting-state functional connectivity between OCD patients and healthy controls (HC) using mega-analysis of data from 1024 OCD patients and 1028 HC from 28 independent samples of the ENIGMA-OCD consortium. We assessed group differences in whole-brain functional connectivity at both the regional and network level, and investigated whether functional connectivity could serve as biomarker to identify patient status at the individual level using machine learning analysis. The mega-analyses revealed widespread abnormalities in functional connectivity in OCD, with global hypo-connectivity (Cohen's d: -0.27 to -0.13) and few hyper-connections, mainly with the thalamus (Cohen's d: 0.19 to 0.22). Most hypo-connections were located within the sensorimotor network and no fronto-striatal abnormalities were found. Overall, classification performances were poor, with area-under-the-receiver-operating-characteristic curve (AUC) scores ranging between 0.567 and 0.673, with better classification for medicated (AUC = 0.702) than unmedicated (AUC = 0.608) patients versus healthy controls. These findings provide partial support for existing pathophysiological models of OCD and highlight the important role of the sensorimotor network in OCD. However, resting-state connectivity does not so far provide an accurate biomarker for identifying patients at the individual level.

Cross-national harmonization of neurocognitive assessment across five sites in a global study.

OBJECTIVE: Cross-national work on neurocognitive testing has been characterized by inconsistent findings, suggesting the need for improved harmonization. Here, we describe a prospective harmonization approach in an ongoing global collaborative study. METHOD: Visuospatial N-Back, Tower of London (ToL), Stop Signal task (SST), Risk Aversion (RA), and Intertemporal Choice (ITC) tasks were administered to 221 individuals from Brazil, India, the Netherlands, South Africa, and the USA. Prospective harmonization methods were employed to ensure procedural similarity of task implementation and processing of derived task measures across sites. Generalized linear models tested for between-site differences controlling for sex, age, education, and socioeconomic status (SES). Associations with these covariates were also examined and tested for differences by site with site-by-covariate interactions. RESULTS: The Netherlands site performed more accurately on N-Back and ToL than the other sites, except for the USA site on the N-Back. The Netherlands and the USA sites performed faster than the other three sites during the go events in the SST. Finally, the Netherlands site also exhibited a higher tolerance for delay discounting than other sites on the ITC, and the India site showed more risk aversion than other sites on the RA task. However, effect size differences across sites on the five tasks were generally small (i.e., partial eta-squared < 0.05) after dropping the Netherlands (on ToL, N-Back, ITC, and SST tasks) and India (on the RA task). Across tasks, regardless of site, the N-Back (sex, age, education, and SES), ToL (sex, age, and SES), SST (age), and ITC (SES) showed associations with covariates. CONCLUSIONS: Four out of the five sites showed only small between-site differences for each task. Nevertheless, despite our extensive prospective harmonization steps, task score performance deviated from the other sites in the Netherlands site (on four tasks) and the India site (on one task). Because the procedural methods were standardized across sites, and our analyses were adjusted for covariates, the differences found in cognitive performance may indicate selection sampling bias due to unmeasured confounders. Future studies should follow similar cross-site prospective harmonization procedures when assessing neurocognition and consider measuring other possible confounding variables for additional statistical control. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Global multi-center and multi-modal magnetic resonance imaging study of obsessive-compulsive disorder: Harmonization and monitoring of protocols in healthy volunteers and phantoms.

OBJECTIVES: We describe the harmonized MRI acquisition and quality assessment of an ongoing global OCD study, with the aim to translate representative, well-powered neuroimaging findings in neuropsychiatric research to worldwide populations. METHODS: We report on T1-weighted structural MRI, resting-state functional MRI, and multi-shell diffusion-weighted imaging of 140 healthy participants (28 per site), two traveling controls, and regular phantom scans. RESULTS: Human image quality measures (IQMs) and outcome measures showed smaller within-site variation than between-site variation. Outcome measures were less variable than IQMs, especially for the traveling controls. Phantom IQMs were stable regarding geometry, SNR, and mean diffusivity, while fMRI fluctuation was more variable between sites. CONCLUSIONS: Variation in IQMs persists, even for an a priori harmonized data acquisition protocol, but after pre-processing they have less of an impact on the outcome measures. Continuous monitoring IQMs per site is valuable to detect potential artifacts and outliers. The inclusion of both cases and healthy participants at each site remains mandatory.

Shape analysis of subcortical structures in obsessive-compulsive disorder and the relationship with comorbid anxiety, depression, and medication use: A meta-analysis by the OCD Brain Imaging Consortium.

OBJECTIVE: Neuroimaging studies of obsessive-compulsive disorder (OCD) patients have highlighted the important role of deep gray matter structures. Less work has however focused on subcortical shape in OCD patients. METHODS: Here we pooled brain MRI scans from 412 OCD patients and 368 controls to perform a meta-analysis utilizing the ENIGMA-Shape protocol. In addition, we investigated modulating effects of medication status, comorbid anxiety or depression, and disease duration on subcortical shape. RESULTS: There was no significant difference in shape thickness or surface area between OCD patients and healthy controls. For the subgroup analyses, OCD patients with comorbid depression or anxiety had lower thickness of the hippocampus and caudate nucleus and higher thickness of the putamen and pallidum compared to controls. OCD patients with comorbid depression had lower shape surface area in the thalamus, caudate nucleus, putamen, hippocampus, and nucleus accumbens and higher shape surface area in the pallidum. OCD patients with comorbid anxiety had lower shape surface area in the putamen and the left caudate nucleus and higher shape surface area in the pallidum and the right caudate nucleus. Further, OCD patients on medication had lower shape thickness of the putamen, thalamus, and hippocampus and higher thickness of the pallidum and caudate nucleus, as well as lower shape surface area in the hippocampus and amygdala and higher surface area in the putamen, pallidum, and caudate nucleus compared to controls. There were no significant differences between OCD patients without co-morbid anxiety and/or depression and healthy controls on shape measures. In addition, there were also no significant differences between OCD patients not using medication and healthy controls. CONCLUSIONS: The findings here are partly consistent with prior work on brain volumes in OCD, insofar as they emphasize that alterations in subcortical brain morphology are associated with comorbidity and medication status. Further work is needed to understand the biological processes contributing to subcortical shape.

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.

Taboo obsessions and their association with suicidality in obsessive-compulsive disorder.

Individuals with obsessive-compulsive disorder (OCD) more often think about, attempt, and die by suicide than individuals from the general population. Sexual and religious obsessions (i.e., taboo obsessions) have been linked to increased risk of suicidality, but it is unclear if they explain additional risk over and above other risk factors. We refined the recently proposed multidimensional hierarchical model of OCD and explored how each symptom dimension in the model was associated with suicidality in a random half (n = 500) of a well-characterized cohort of patients with OCD. Symptom dimensions and other risk factors significantly associated with suicidality were included in a confirmatory multivariable model conducted with the other half of the sample (n = 501). The predictive confirmatory model accounted for 19% of the variance in suicidality. Taboo obsessions, the general OCD factor (i.e., having many different OCD symptoms at the same time), lifetime major depression, and lifetime substance use disorders significantly predicted suicidality in this model. Lifetime major depression explained most unique variance in suicidality (5.6%) followed by taboo obsessions and the general OCD factor (1.9% each). Taboo obsessions explain a small but significant proportion of variance in suicidality and should be considered an independent risk factor for suicidality in patients with OCD.

Neurocircuit models of obsessive-compulsive disorder: limitations and future directions for research.

Obsessive-compulsive disorder (OCD) is a common psychiatric condition classically characterized by obsessions (recurrent, intrusive and unwanted thoughts) and compulsions (excessive, repetitive and ritualistic behaviors or mental acts). OCD is heterogeneous in its clinical presentation and not all patients respond to first-line treatments. Several neurocircuit models of OCD have been proposed with the aim of providing a better understanding of the neural and cognitive mechanisms involved in the disorder. These models use advances in neuroscience and findings from neuropsychological and neuroimaging studies to suggest links between clinical profiles that reflect the symptoms and experiences of patients and dysfunctions in specific neurocircuits. Several models propose that treatments for OCD could be improved if directed to specific neurocircuit dysfunctions, thereby restoring efficient neurocognitive function and ameliorating the symptomatology of each associated clinical profile. Yet, there are several important limitations to neurocircuit models of OCD. The purpose of the current review is to highlight some of these limitations, including issues related to the complexity of brain and cognitive function, the clinical presentation and course of OCD, etiological factors, and treatment methods proposed by the models. We also provide suggestions for future research to advance neurocircuit models of OCD and facilitate translation to clinical application.

Neurocircuit models of obsessive-compulsive disorder: limitations and future directions for research

Obsessive-compulsive disorder (OCD) is a common psychiatric condition classically characterized by obsessions (recurrent, intrusive and unwanted thoughts) and compulsions (excessive, repetitive and ritualistic behaviors or mental acts). OCD is heterogeneous in its clinical presentation and not all patients respond to first-line treatments. Several neurocircuit models of OCD have been proposed with the aim of providing a better understanding of the neural and cognitive mechanisms involved in the disorder. These models use advances in neuroscience and findings from neuropsychological and neuroimaging studies to suggest links between clinical profiles that reflect the symptoms and experiences of patients and dysfunctions in specific neurocircuits. Several models propose that treatments for OCD could be improved if directed to specific neurocircuit dysfunctions, thereby restoring efficient neurocognitive function and ameliorating the symptomatology of each associated clinical profile. Yet, there are several important limitations to neurocircuit models of OCD. The purpose of the current review is to highlight some of these limitations, including issues related to the complexity of brain and cognitive function, the clinical presentation and course of OCD, etiological factors, and treatment methods proposed by the models. We also provide suggestions for future research to advance neurocircuit models of OCD and facilitate translation to clinical application.

The thalamus and its subnuclei-a gateway to obsessive-compulsive disorder.

Larger thalamic volume has been found in children with obsessive-compulsive disorder (OCD) and children with clinical-level symptoms within the general population. Particular thalamic subregions may drive these differences. The ENIGMA-OCD working group conducted mega- and meta-analyses to study thalamic subregional volume in OCD across the lifespan. Structural T1-weighted brain magnetic resonance imaging (MRI) scans from 2649 OCD patients and 2774 healthy controls across 29 sites (50 datasets) were processed using the FreeSurfer built-in ThalamicNuclei pipeline to extract five thalamic subregions. Volume measures were harmonized for site effects using ComBat before running separate multiple linear regression models for children, adolescents, and adults to estimate volumetric group differences. All analyses were pre-registered ( https://osf.io/73dvy ) and adjusted for age, sex and intracranial volume. Unmedicated pediatric OCD patients (<12 years) had larger lateral (d = 0.46), pulvinar (d = 0.33), ventral (d = 0.35) and whole thalamus (d = 0.40) volumes at unadjusted p-values <0.05. Adolescent patients showed no volumetric differences. Adult OCD patients compared with controls had smaller volumes across all subregions (anterior, lateral, pulvinar, medial, and ventral) and smaller whole thalamic volume (d = -0.15 to -0.07) after multiple comparisons correction, mostly driven by medicated patients and associated with symptom severity. The anterior thalamus was also significantly smaller in patients after adjusting for thalamus size. Our results suggest that OCD-related thalamic volume differences are global and not driven by particular subregions and that the direction of effects are driven by both age and medication status.

Factor structure of the Dimensional Yale-Brown Obsessive-Compulsive Scale in a large sample of adults with obsessive-compulsive disorder

Objectives: Although the Dimensional Yale-Brown Obsessive-Compulsive Scale (DY-BOCS) is a widely used instrument for assessing different obsessive-compulsive symptom dimensions, its factor structure has never been studied in a Brazilian population. Thus, we aimed to assess the goodness-of-fit indexes and factor loadings of two higher-order models of the DY-BOCS using confirmatory factor analysis (CFA) in a large obsessive-compulsive disorder (OCD) sample. Methods: We tested two CFA models in a sample of 955 adults with OCD who had been assessed with the DY-BOCS in a cross-sectional multi-site study. The first model encompassed the symptom checklist (present or absent), whereas the second focused on items related to severity scores. Results: Both models presented adequate goodness-of-fit indexes. The comparative fit index, Tucker-Lewis index, and omega were > 0.9, while the root mean square error of approximation was ≤ 0.06 for both models. Factor loadings for each item of each dimension are presented and discussed. Conclusion: Higher-order factor models showed adequate goodness-of-fit indexes, indicating that they appropriately measured OCD dimensions in this Brazilian population.

Factor structure of the Dimensional Yale-Brown Obsessive-Compulsive Scale in a large sample of adults with obsessive-compulsive disorder.

OBJECTIVES: Although the Dimensional Yale-Brown Obsessive-Compulsive Scale (DY-BOCS) is a widely used instrument for assessing different obsessive-compulsive symptom dimensions, its factor structure has never been studied in a Brazilian population. Thus, we aimed to assess the goodness-of-fit indexes and factor loadings of two higher-order models of the DY-BOCS using confirmatory factor analysis (CFA) in a large obsessive-compulsive disorder (OCD) sample. METHODS: We tested two CFA models in a sample of 955 adults with OCD who had been assessed with the DY-BOCS in a cross-sectional multi-site study. The first model encompassed the symptom checklist (present or absent), whereas the second focused on items related to severity scores. RESULTS: Both models presented adequate goodness-of-fit indexes. The comparative fit index, Tucker-Lewis index, and omega were > 0.9, while the root mean square error of approximation was ≤ 0.06 for both models. Factor loadings for each item of each dimension are presented and discussed. CONCLUSION: Higher-order factor models showed adequate goodness-of-fit indexes, indicating that they appropriately measured OCD dimensions in this Brazilian population.

Association Between Obsessive-Compulsive Symptom Dimensions in Mothers and Psychopathology in Their Children.

Background: The non-clinical presentation of obsessive-compulsive symptoms (OCS) in women may impact not only their daily lives and well-being but also increase the risk for emotional and behavioral problems in their children. This study aims to investigate the OCS dimension distribution in a large sample of mothers from a cohort of school age children and the association between these OCS dimensions with their own psychopathology, and with the presence of OCS and other psychopathology in their children. Method: Our final sample consisted of 2,511 mother-children dyads recruited from the elementary schools of two large cities. Throughout multiple regression analysis, we examined the correlations between demographic and clinical variables of mothers assessed by the Mini International Psychiatric Interview (MINI) and the Dimensional Yale-Brown Obsessive-Compulsive Scale-Short Version (DY-BOCS-SV) with children's psychopathology status reported by the Child Behavior Checklist (CBCL). Results: The overall prevalence of mothers who reported experiencing at least one OCS was 40% (N = 1,004). "Aggression/violence" was the most frequent symptom dimension (32.2%), followed by the "symmetry/ordering" (16.4%) and the "sexual/religious" dimensions (13.8%). There was a significant correlation between the presence of OCS and maternal psychopathology in general (p < 0.001, r = 0.397). Not only the presence but also the severity of the mother's OCS were strongly correlated to the total (p < 0.001), internalizing (p < 0.001), externalizing (p < 0.001), and OCS subscale scores (p < 0.001) on the CBCL. Conclusion: OCS dimensions are highly prevalent in women. Presence and severity of maternal OCS are related to children's psychopathology and behavioral problems.

Obsessive-Compulsive Symptoms, Polygenic Risk Score, and Thalamic Development in Children From the Brazilian High-Risk Cohort for Mental Conditions (BHRCS).

Background: Thalamic volume measures have been linked to obsessive-compulsive disorder (OCD) in children and adolescents. However, it is unclear if alterations in thalamic volumes occur before or after symptom onset and if there is a relation to the presence of sub-clinical obsessive-compulsive symptoms (OCS). Here, we explore the relationship between OCS and the rate of thalamic volume change in a cohort of children and youth at high risk to develop a mental disorder. A secondary aim was to determine if there is a relationship between OCS and the individual's OCD polygenic risk score (OCD-PRS) and between the rate of thalamic volume change and the OCD-PRS. Methods: The sample included 378 children enrolled in the longitudinal Brazilian High-Risk Cohort for Mental Conditions. Participants were assessed for OCS and the symmetrized percent change (SPC) of thalamic volume across two time-points separated by 3 years, along with the OCD-PRS. Zero-altered negative binomial models were used to analyze the relationship between OCS and thalamic SPC. Multiple linear regressions were used to examine the relationship between thalamic SPC and OCD-PRS. Results: A significant relationship between OCS and the right thalamus SPC (p = 0.042) was found. There was no significant relationship between changes in thalamic volume SPC and OCD-PRS. Conclusions: The findings suggest that changes in the right thalamic volume over the course of 3 years in children may be associated to OCS. Future studies are needed to confirm these results and further characterize the specific nature of OCS symptoms associated with thalamic volumes.