Insula volumes in psychosis probands
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Abstract
Insula is postulated to be a critical cortical region with extensive cortico-limbic connections and is hypothesized to play a role in pain/auditory/facial affect processing and interoception. Morphological abnormalities in this region may contribute to schizophrenia (SZ), schizoaffective disorder (SAD), and psychotic Bipolar disorder (BDP) symptomatology. Previous studies of insula have led to somewhat inconsistent results. Few studies have separately examined the left and right insula's anterior and posterior components, which have distinct functional roles. This study will examine the morphological and cognitive changes which occur in psychosis within the left and right insula, bilateral insula, and anterior and posterior insula. Although the exact localization of these deficits is inconsistent, we postulate that control groups will have greater volume, thickness, and local Gyrification Index (LGI) across all measures compared to psychosis groups, with greater reductions confined to the anterior insula since it is hypothesized to play a role in higher-order processing. Due to the hypothesized decrease in LGI in psychosis groups, we postulate to see the most significant correlations in LGI, supporting the view that decreases in gyrification correlate to decreases in cognitive abilities (Gautam et al., 2015; Park et al., 2021). T1-MPRAGE scans were obtained using 3T MRI scans. Insula measurements were extracted using FreeSurfer (FS) 7.1 in healthy controls (NC=935) and psychosis probands (SZ=481, SAD=383, BDP=381). FS measures were correlated with cognition (verbal memory (VM), verbal fluency (VF), digit sequencing (DS), and symbol coding (SC)), and symptomatology in SZ/SAD/BPD. P values < 0.05 adjusted for False Discovery Rate (FDR) were reported. Our observations suggest structural alterations in the insula, predominantly in volume, thickness, and LGI, across affective and non-affective psychotic disorders. Though we observed relations between the insula and cognitive measures, we did not see correlations with symptomatology. Future studies will examine further the relation between insular structure and socio-emotional and self-processing believed to be related to the anterior insula.
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Attribution 4.0 International