Publications by authors named "Brian P Brennan"

Article Synopsis
  • Obsessive-compulsive disorder (OCD) affects about 1% of people and has a strong genetic component, but previous studies have not fully explained its genetic causes or biological mechanisms.
  • A large genome-wide association study (GWAS) analyzed data from over 53,000 OCD cases and over 2 million control participants, identifying 30 significant genetic markers related to OCD and suggesting a 6.7% heritability from SNPs.
  • The research also found 249 candidate risk genes linked to OCD, particularly in specific brain regions, and showed genetic correlations with various psychiatric disorders, laying the groundwork for further studies and potential treatments.
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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.

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Objective: Cognitive-behavioral therapy (CBT) is considered a first-line treatment for obsessive-compulsive disorder (OCD) in pediatric and adult populations. Nevertheless, some patients show partial or null response. The identification of predictors of CBT response may improve clinical management of patients with OCD.

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Initial controlled trials of the serotonergic antidepressant fluvoxamine showed promise for treatment of mild to moderate COVID-19 in outpatients, although more recent outpatient data have been less encouraging. Turning to studies of hospitalized patients, a retrospective cohort study by Hoertel and associates in 2021 found a markedly reduced risk of intubation or death among patients hospitalized with COVID-19 who were receiving serotonergic antidepressants at the time of admission vs. those not receiving antidepressants.

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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.

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Obsessive-compulsive disorder (OCD) affects approximately one person in 40 and causes substantial suffering. Evidence-based treatments can benefit many; however, optimal treatment can be difficult to access. Diagnosis is frequently delayed, and pharmacological and psychotherapeutic interventions often fail to follow evidence-based guidelines.

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Article Synopsis
  • Scientists want to find ways to diagnose obsessive-compulsive disorder (OCD) using brain scans, but so far, there are no good tests.
  • They studied a lot of data from almost 2,300 OCD patients and over 2,000 healthy people using special MRI scans.
  • They discovered that the brain's differences could show up based on whether patients took medication, which made it harder to use these scans as a reliable way to understand OCD.
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Article Synopsis
  • - Large-scale neuroimaging studies show differences in cortical thickness in various psychiatric disorders, but the biological reasons for these differences are not fully understood.
  • - The study aimed to identify neurobiological correlates of cortical thickness variations between affected individuals and controls across six disorders: ADHD, ASD, BD, MDD, OCD, and schizophrenia.
  • - Using data from 145 cohorts and advanced imaging techniques, the analysis revealed distinct patterns of cortical thickness associated with specific gene expressions in disorders, involving a total of over 28,000 participants.
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Article Synopsis
  • The study compares ADHD, ASD, and OCD using brain imaging data from over 5,000 healthy controls and numerous patients across different age groups, focusing on structural differences in the brain.
  • No consistent differences were observed across all three disorders, with some specific findings like smaller hippocampal volumes in children with ADHD compared to OCD.
  • The results highlight that while subtle differences exist between these disorders, the distinctions are most apparent in specific age groups, emphasizing ADHD's unique brain volume differences in younger individuals and ASD's cortical thickness variations in adults.
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Neuroimaging has played an important part in advancing our understanding of the neurobiology of obsessive-compulsive disorder (OCD). At the same time, neuroimaging studies of OCD have had notable limitations, including reliance on relatively small samples. International collaborative efforts to increase statistical power by combining samples from across sites have been bolstered by the ENIGMA consortium; this provides specific technical expertise for conducting multi-site analyses, as well as access to a collaborative community of neuroimaging scientists.

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Article Synopsis
  • Scientists studied the brains of kids and adults with obsessive-compulsive disorder (OCD) to see if there are differences in brain structure on either side.
  • They looked at a lot of data from different patients and healthy people using special brain scans.
  • They found that kids with OCD had small differences in certain brain structures, but adults with OCD didn’t show these differences, which might mean kids’ brains develop differently when they have OCD.
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Functional MRI (fMRI) studies have traditionally relied on intersubject normalization based on global brain morphology, which cannot establish proper functional correspondence between subjects due to substantial intersubject variability in functional organization. Here, we reliably identified a set of discrete, homologous functional regions in individuals to improve intersubject alignment of fMRI data. These functional regions demonstrated marked intersubject variability in size, position, and connectivity.

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Background: This study investigated distinct trajectories of treatment response in a naturalistic intensive/residential treatment (IRT) program for adults with severe obsessive-compulsive disorder (OCD). We hypothesized that: (1) distinct trajectories would emerge and (2) demographic variables, psychiatric comorbidity, OCD symptom subtype, level of insight, previous exposure and response prevention (ERP) treatment, and quality of life, would differentially predict assignment to these trajectories.

Methods: Participants included 305 individuals with primary OCD admitted for IRT.

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Background: Existing functional connectivity studies of obsessive-compulsive disorder (OCD) support a model of circuit dysfunction. However, these group-level observations have failed to yield neuroimaging biomarkers sufficient to serve as a test for the OCD diagnosis, predict current or future symptoms, or predict treatment response, perhaps because these studies failed to account for the substantial intersubject variability in structural and functional brain organization.

Methods: We used functional regions, localized in each of 41 individual OCD patients, to identify cortical connectivity biomarkers of both global and dimension-specific symptom severity and to detect functional connections that track changes in symptom severity following intensive residential treatment.

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Importance: Obsessive-compulsive disorder (OCD) is a common and often debilitating psychiatric illness. Recent advances in the understanding of the neuroscience of OCD have provided valuable insights that have begun to transform the way we think about the management of this disorder. This educational review provides an integrated neuroscience perspective on formulation and treatment planning for patients with OCD.

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Objectives: A shorter version of the Obsessive Beliefs Questionnaire (OBQ-44) is needed to promote the use of this measure in research and increase our understanding of cognitive phenomena maintaining obsessive-compulsive disorder (OCD). Additionally, an abbreviated version of the OBQ-44 would encourage frequent monitoring of dysfunctional beliefs in intensive care settings. This study aimed to validate a nine-item version of the questionnaire (OBQ-9).

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Objective: This study aimed to develop and validate the Distress Tolerance Scale-Short Form (DTS-SF), a modification of the original Distress Tolerance Scale, in a severe/complex sample of individuals with obsessive compulsive disorder (OCD). Currently, there are multiple self-report measurements of distress tolerance (DT), highlighting the need for a more refined measure.

Method: Participants included 222 individuals with a primary diagnosis of OCD (57% male, average age = 31) seeking intensive/residential treatment.

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Little is known about the acute effects of antidepressant treatments on brain glutamate and gamma-amino-butyric acid (GABA) levels, and their association with clinical response. Using proton magnetic resonance spectroscopy (H-MRS) we examined longitudinally the effects of citalopram on glutamine/glutamate ratios and GABA levels in the pregenual anterior cingulate cortex (pgACC) of individuals with major depressive disorder (MDD). We acquired H-MRS scans at baseline and at days 3, 7, and 42 of citalopram treatment in nineteen unmedicated individuals with MDD.

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Objective: Exposure and response prevention (ERP) is an effective treatment for individuals with obsessive-compulsive disorder (OCD), yet a substantial number of individuals with OCD do not fully respond to this intervention. Based on emerging experimental and clinical research on acceptance, this study sought to explore whether willingness to experience unpleasant thoughts, emotions, and bodily sensations during ERP was associated with improved treatment response.

Methods: Two hundred eighty-eight adults with OCD receiving residential ERP provided self-rated willingness and other exposure-related variables during each daily coached ERP session.

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Background: Several lines of evidence support the hypothesis that lower cerebral levels of glutathione (GSH), associated with increased oxidative stress, may contribute to obsessive-compulsive disorder (OCD). However, no studies to date have investigated brain GSH levels in individuals with OCD.

Methods: Twenty-nine individuals with OCD and 25 age-, sex-, and race-matched comparison individuals without OCD underwent single voxel 2D J-resolved proton magnetic resonance spectroscopy (MRS) to examine GSH levels in the posterior cingulate cortex (PCC).

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Background: Anabolic-androgenic steroid (AAS) use is associated with psychiatric symptoms including increased aggression as well as with cognitive dysfunction. The brain effects of long-term AAS use have not been assessed in humans.

Methods: This multimodal magnetic resonance imaging study of the brain compared 10 male weightlifters reporting long-term AAS use with 10 age-matched weightlifters reporting no AAS exposure.

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The anterior cingulate cortex is implicated in the neurobiology of obsessive-compulsive disorder (OCD). However, few studies have examined functional and neurochemical abnormalities specifically in the rostral subdivision of the ACC (rACC) in OCD patients. We used functional magnetic resonance imaging (fMRI) during an emotional counting Stroop task and single-voxel J-resolved proton magnetic resonance spectroscopy ((1)H-MRS) in the rACC to examine the function and neurochemistry of the rACC in individuals with OCD and comparison individuals without OCD.

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