Marcelo Q Hoexter

University of São Paulo, São Paulo, Estado de Sao Paulo, Brazil

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Publications (3)10.65 Total impact

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    Article: Obsessive-compulsive symptom dimensions correlate to specific gray matter volumes in treatment-naïve patients.
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    ABSTRACT: BACKGROUND: Clinical and sociodemographic findings have supported that OCD is heterogeneous and composed of multiple potentially overlapping and stable symptom dimensions. Previous neuroimaging investigations have correlated different patterns of OCD dimension scores and gray matter (GM) volumes. Despite their relevant contribution, some methodological limitations, such as patient's previous medication intake, may have contributed to inconsistent findings. METHOD: Voxel-based morphometry was used to investigate correlations between regional GM volumes and symptom dimensions severity scores in a sample of 38 treatment-naïve OCD patients. Several standardized instruments were applied, including an interview exclusively developed for assessing symptom dimensions severity (DY-BOCS). RESULTS: Scores on the "aggression" dimension were positively correlated with GM volumes in lateral parietal cortex in both hemispheres and negatively correlated with bilateral insula, left putamen and left inferior OFC. Scores on the "sexual/religious" dimension were positively correlated with GM volumes within the right middle lateral OFC and right DLPFC and negatively correlated with bilateral ACC. Scores on the "hoarding" dimension were positively correlated with GM volumes in the left superior lateral OFC and negatively correlated in the right parahippocampal gyrus. No significant correlations between GM volumes and the "contamination" or "symmetry" dimensions were found. CONCLUSIONS: Building upon preexisting findings, our data with treatment-naïve OCD patients have demonstrated distinct GM substrates implicated in both cognitive and emotion processing across different OCS dimensions.
    Journal of psychiatric research 10/2012; · 3.72 Impact Factor
  • Article: Differential prefrontal gray matter correlates of treatment response to fluoxetine or cognitive-behavioral therapy in obsessive-compulsive disorder.
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    ABSTRACT: Nearly one-third of patients with obsessive-compulsive disorder (OCD) fail to respond to adequate therapeutic approaches such as serotonin reuptake inhibitors and/or cognitive-behavioral therapy (CBT). This study investigated structural magnetic resonance imaging (MRI) correlates as potential pre-treatment brain markers to predict treatment response in treatment-naïve OCD patients randomized between trials of fluoxetine or CBT. Treatment-naïve OCD patients underwent structural MRI scans before randomization to a 12-week clinical trial of either fluoxetine or group-based CBT. Voxel-based morphometry was used to identify correlations between pretreatment regional gray matter volume and changes in symptom severity on the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Brain regional correlations of treatment response differed between treatment groups. Notably, symptom improvement in the fluoxetine treatment group (n=14) was significantly correlated with smaller pretreatment gray matter volume within the right middle lateral orbitofrontal cortex (OFC), whereas symptom improvement in the CBT treatment group (n=15) was significantly correlated with larger pretreatment gray matter volume within the right medial prefrontal cortex (mPFC). No significant a priori regional correlations of treatment response were identified as common between the two treatment groups when considering the entire sample (n=29). These findings suggest that pretreatment gray matter volumes of distinct brain regions within the lateral OFC and mPFC were differentially correlated to treatment response to fluoxetine versus CBT in OCD patients. This study further implicates the mPFC in the fear/anxiety extinction process and stresses the importance of lateral portions of the OFC in mediating fluoxetine's effectiveness in OCD. Clinical registration information: http://clinicaltrials.gov-NCT00680602.
    European neuropsychopharmacology: the journal of the European College of Neuropsychopharmacology 07/2012; · 3.68 Impact Factor
  • Article: Neuropsychological predictors of response to randomized treatment in obsessive-compulsive disorder.
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    ABSTRACT: To identify neuropsychological predictors of treatment response to cognitive-behavioral therapy (CBT) and fluoxetine in treatment-naïve adults with obsessive-compulsive disorder (OCD). Thirty-eight adult outpatients with OCD underwent neuropsychological assessment, including tasks of intellectual function, executive functioning and visual and verbal memory, before randomization to a 12-week clinical trial of either CBT or fluoxetine. Neuropsychological measures were used to identify predictors of treatment response in OCD. Neuropsychological measures that predicted a better treatment response to either CBT or fluoxetine were higher verbal IQ (Wechsler Abbreviated Scale of Intelligence) (p=0.008); higher verbal memory on the California Verbal Learning Test (p=0.710); shorter time to complete part D (Dots) (p<0.001), longer time to complete part W (Words) (p=0.025) and less errors on part C (Colors) (p<0.001) in the Victoria Stroop Test (VST). Fewer perseverations on the California Verbal Learning Test, a measure of mental flexibility, predicted better response to CBT, but worse response to fluoxetine (p=0.002). In general, OCD patients with better cognitive and executive abilities at baseline were more prone to respond to either CBT or fluoxetine. Our finding that neuropsychological measures of mental flexibility predicted response to treatment in opposite directions for CBT and fluoxetine suggests that OCD patients with different neuropsychological profiles may respond preferentially to one type of treatment versus the other. Further studies with larger samples of OCD patients are necessary to investigate the heuristic value of such findings in a clinical context.
    Progress in Neuro-Psychopharmacology and Biological Psychiatry 07/2012; 39(2):310-7. · 3.25 Impact Factor