Abstract
ObjectThe aim of this study was to investigate macrostructural and microstructural brain changes in patients with pure obsessive compulsive disorder (OCD) and to examine the relationship between brain structure and neuropsychological deficits.Method20 patients with OCD underwent a comprehensive neuropsychological battery. A combined voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) analysis was used to capture gray matter (GM) and white matter changes in OCD patients as compared to pair-matched healthy volunteers. Multiple regression designs explored the relationship between cognition and neuroimaging parameters.ResultsOCD patients had increased mean diffusivity (MD) in GM nodes of the orbitofronto-striatal loop (left dorsal anterior cingulate [Z = 3.67, P < 0.001] left insula [Z = 3.35 P < 0.001] left thalamus [Z = 3.59, P < 0.001] left parahippocampal gyrus [Z = 3.77 P < 0.001]) and in lateral frontal and posterior associative cortices (right frontal operculum [Z = 3.42 P < 0.001], right temporal lobe [Z = 3.79 P < 0.001] left parietal lobe [Z = 3.91 P < 0.001]). Decreased fractional anisotropy (FA) was detected in intrahemispheric (left superior longitudinal fasciculus [Z = 4.07 P < 0.001]) and interhemispheric (body of corpus callosum [CC, Z = 4.42 P < 0.001]) bundles. Concurrently, the semantic fluency score, a measure of executive control processes, significantly predicted OCD diagnosis (Odds Ratio = 1.37; 95% Confidence Intervals = 1.09–1.73; P = 0.0058), while variation in performance was correlated with increased MD in left temporal (Z = 4.25 P < 0.001) and bilateral parietal regions (left Z = 3.94, right Z = 4.19 P < 0.001), and decreased FA in the right posterior corona radiata (Z = 4.07 P < 0.001) and the left corticospinal tract (Z = 3.95 P < 0.001).ConclusionsThe reported deficit in executive processes and the underlying microstructural alterations may qualify as behavioral and biological markers of OCD.
Highlights
Current conceptualization of obsessive compulsive disorder (OCD) suggests that neurobiological abnormalities are crucial factors mediating the etiology and phenomenology of the illness
A number of voxel-based morphometry (VBM) investigations have shown increased gray matter (GM) volume in the orbitofrontal cortex (OFC) and other cerebral structures belonging to the orbitofronto-striatal loop of OCD patients (Scarone et al 1992; Kim et al 2001; Valente et al 2005; Christian et al 2008), findings have been conflicting with reports of reduced brain a 2014 The Authors
We analyze the neuropsychological profile of pure OCD patients and demonstrate that reduced semantic fluency is a neurocognitive marker of the illness
Summary
Current conceptualization of obsessive compulsive disorder (OCD) suggests that neurobiological abnormalities are crucial factors mediating the etiology and phenomenology of the illness. The most widely accepted model of OCD proposes that abnormalities of corticostriatal circuits, involving the orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), thalamus and striatum play an important role in its pathophysiology (Graybiel and Rauch 2000; Saxena and Rauch 2000; Menzies et al 2008a; Harrison et al 2009). Such biological model has been partially validated by direct and indirect investigations of the possible circuits involved in the pathogenesis of the disorder.
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