title: Brain microstructural changes and cognitive correlates in patients with pure obsessive compulsive disorder.
abstract: OBJECTIVE
  The 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.
  
  
  METHODS
  20 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.
  
  
  RESULTS
  OCD 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).
  
  
  CONCLUSIONS
  The reported deficit in executive processes and the underlying microstructural alterations may qualify as behavioral and biological markers of OCD.
authors.affiliation: Department of Clinical and Behavioral Neurology, Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation Via Ardeatina 306, 00179, Rome, Italy.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Spalletta
authors.affiliation: Department of Clinical and Behavioral Neurology, Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation Via Ardeatina 306, 00179, Rome, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Piras
authors.affiliation: Department of Clinical and Behavioral Neurology, Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation Via Ardeatina 306, 00179, Rome, Italy.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Fagioli
authors.affiliation: Department of Clinical and Behavioral Neurology, Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation Via Ardeatina 306, 00179, Rome, Italy ; Department of Neuroscience, Tor Vergata University of Rome Rome, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Caltagirone
authors.affiliation: Department of Clinical and Behavioral Neurology, Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation Via Ardeatina 306, 00179, Rome, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Piras
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology* / Q000503:physiopathology; D056324:Diffusion Tensor Imaging / Q000379:methods*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009771:Obsessive-Compulsive Disorder / Q000473:pathology* / Q000503:physiopathology*
keywords: DTI; VBM; neuroimaging; neuropsychology; obsessive compulsive disorder