Frontal and temporal cortical volume, white matter tract integrity, and hemispheric asymmetry in schizotypal personality disorder

Abstract

Abnormalities in temporal and frontal cortical volume, white matter tract integrity, and hemispheric asymmetry have been implicated in schizophrenia-spectrum disorders. Schizotypal personality disorder can provide insight into vulnerability and protective factors in these disorders without the confounds associated with chronic psychosis. However, multimodal imaging and asymmetry studies in SPD are sparse. Thirty-seven individuals with SPD and 29 healthy controls (HC) received clinical interviews and 3T magnetic resonance T1-weighted and diffusion tensor imaging scans. Mixed ANOVAs were performed on gray matter volumes of the lateral temporal regions involved in auditory and language processing and dorsolateral prefrontal cortex involved in executive functioning, as well as fractional anisotropy (FA) of prominent white matter tracts that connect frontal and temporal lobes. In the temporal lobe regions, there were no group differences in volume, but SPD had reduced right>left middle temporal gyrus volume asymmetry compared to HC and lacked the right>left asymmetry in the inferior temporal gyrus volume seen in HC. In the frontal regions, there were no differences between groups on volume or asymmetry. In the white matter tracts, SPD had reduced FA in the left sagittal stratum and superior longitudinal fasciculus, and increased right>left asymmetry in sagittal stratum FA compared to HC. In the SPD group, lower left superior longitudinal fasciculus FA was associated with greater severity of disorganization symptoms. Findings suggest that abnormities in structure and asymmetry of temporal regions and frontotemporal white matter tract integrity are implicated in SPD pathology.

Keywords: Brain asymmetry; Diffusion tensor imaging; Fractional anisotropy; Magnetic resonance imaging; Schizotypal personality disorder.

Fig. 1.

(a) Segmentation of frontal and temporal regions of interest in the present study. (b) White matter tracts of interest in the present study.

Fig. 2.

(a) Temporal lobe volume Group x Hemi x Region interaction, F(2, 59) = 3.15, p < .05, ${\eta }_p^2=0.097$, mean ± SE. Post hoc tests did not reveal any significant between-group differences in volume. (b) Group differences in temporal lobe volume asymmetry, mean ± SE.

Fig. 3.

(a) White matter tract fractional anisotropy Group × Hemi × Tract interaction, F(2, 60) = 4.50, p = .015, ${\eta }_p^2=0.130$, mean volume ± SE. (b) Group differences in white matter tract fractional anisotropy asymmetry, mean ± SE.