title: Anterior limb of the internal capsule in schizotypal personality disorder: fiber-tract counting, volume, and anisotropy.
abstract: Mounting evidence suggests that white matter abnormalities and altered subcortical-cortical connectivity may be central to the pathology of schizophrenia (SZ). The anterior limb of the internal capsule (ALIC) is an important thalamo-frontal white-matter tract shown to have volume reductions in SZ and to a lesser degree in schizotypal personality disorder (SPD). While fractional anisotropy (FA) and connectivity abnormalities in the ALIC have been reported in SZ, they have not been examined in SPD. In the current study, magnetic resonance (MRI) and diffusion tensor imaging (DTI) were obtained in age- and sex-matched individuals with SPD (n=33) and healthy controls (HCs; n=38). The ALIC was traced bilaterally on five equally spaced dorsal-to-ventral axial slices from each participant's MRI scan and co-registered to DTI for the calculation of FA. Tractography was used to examine tracts between the ALIC and two key Brodmann areas (BAs; BA10, BA45) within the dorsolateral prefrontal cortex (DLPFC). Compared with HCs, the SPD participants exhibited (a) smaller relative volume at the mid-ventral ALIC slice level but not the other levels; (b) normal FA within the ALIC; (c) fewer relative number of tracts between the most-dorsal ALIC levels and BA10 but not BA45 and (d) fewer dorsal ALIC-DLPFC tracts were associated with greater symptom severity in SPD. In contrast to prior SZ studies that report lower FA, individuals with SPD show sparing. Our findings are consistent with a pattern of milder thalamo-frontal dysconnectivity in SPD than schizophrenia.
authors.affiliation: Department of Psychiatry, Mount Sinai School of Medicine, New York, NY, USA. erin.hazlett@mssm.edu
authors.forename: Erin A
authors.initials: EA
authors.lastname: Hazlett
authors.forename: Tyson
authors.initials: T
authors.lastname: Collazo
authors.forename: Yuliya
authors.initials: Y
authors.lastname: Zelmanova
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Entis
authors.forename: King-Wai
authors.initials: KW
authors.lastname: Chu
authors.forename: Kim E
authors.initials: KE
authors.lastname: Goldstein
authors.forename: Panos
authors.initials: P
authors.lastname: Roussos
authors.forename: M Mehmet
authors.initials: MM
authors.lastname: Haznedar
authors.forename: Harold W
authors.initials: HW
authors.lastname: Koenigsberg
authors.forename: Antonia S
authors.initials: AS
authors.lastname: New
authors.forename: Monte S
authors.initials: MS
authors.lastname: Buchsbaum
authors.forename: Julian P
authors.initials: JP
authors.lastname: Hershowitz
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Siever
authors.forename: William
authors.initials: W
authors.lastname: Byne
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016880:Anisotropy; D001931:Brain Mapping; D016022:Case-Control Studies; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D020772:Internal Capsule / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D012569:Schizotypal Personality Disorder / Q000473:pathology*; D055815:Young Adult