Abstract
Obsessive-compulsive disorder (OCD) is a clinically heterogeneous condition. Although structural brain alterations have been consistently reported in OCD, their interaction with particular clinical subtypes deserves further examination. Among other approaches, a two-group classification in patients with autogenous and reactive obsessions has been proposed. The purpose of the present study was to assess, by means of a voxel-based morphometry analysis, the putative brain structural correlates of this classification scheme in OCD patients. Ninety-five OCD patients and 95 healthy controls were recruited. Patients were divided into autogenous (n = 30) and reactive (n = 65) sub-groups. A structural magnetic resonance image was acquired for each participant and pre-processed with SPM8 software to obtain a volume-modulated gray matter map. Whole-brain and voxel-wise comparisons between the study groups were then performed. In comparison to the autogenous group, reactive patients showed larger gray matter volumes in the right Rolandic operculum. When compared to healthy controls, reactive patients showed larger volumes in the putamen (bilaterally), while autogenous patients showed a smaller left anterior temporal lobe. Also in comparison to healthy controls, the right middle temporal gyrus was smaller in both patient subgroups. Our results suggest that autogenous and reactive obsessions depend on partially dissimilar neural substrates. Our findings provide some neurobiological support for this classification scheme and contribute to unraveling the neurobiological basis of clinical heterogeneity in OCD.
Highlights
In recent years there has been an increasing interest in studying the clinical heterogeneity of obsessive-compulsive disorder (OCD) [1,2,3]
Subjects A total of 192 subjects were scanned, two patients were excluded from the final sample as they reported obsessions of both an autogenous and reactive nature
No differences between patients and healthy controls were observed in age, gender or handedness
Summary
In recent years there has been an increasing interest in studying the clinical heterogeneity of obsessive-compulsive disorder (OCD) [1,2,3]. Reports comparing patients with different symptom profiles have identified differences in their sociodemographical and clinical features, as well as neurobiological correlates. In symptom provocation studies, relatively distinctive patterns of brain activity have been associated with the presentation of stimuli representing discrete OCD symptom dimensions, such as aggression/checking and contamination/cleaning symptoms [6,7,8]. Studies of brain structural alterations in OCD have resulted in a mostly consistent pattern of findings [9,10,11], the assessment of such alterations in relation to specific symptoms or illness subtypes has provided mixed results. While in some assessments contamination/cleaning and symmetry/ordering symptoms were associated with volume reductions in the dorsal caudate and the sensorimotor cortex, respectively [13], in others such symptoms did not show any significant correlation with brain anatomy [14]
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