Aberrant anterior insula underlies interoceptive deficits in alexithymia among schizophrenia patients

This study aims to investigate the unique neural mechanisms underpinning abnormal interoception in schizophrenia patients with comorbid alexithymia. The focus is on identifying aberrant activation patterns and functional connectivities of the insula cortex with regions involved in emotional processing. Fifty schizophrenia patients were assessed using the Toronto Alexithymia Scale (TAS) and the Multidimensional Assessment of Interoceptive Awareness (MAIA). Task-based fMRI scans were conducted to observe brain activation patterns during interoceptive conditions. Alexithymic patients showed higher alexithymia and lower interoception compared to non-alexithymic patients. During the interoceptive task, alexithymic patients exhibited reduced activation in the anterior insula (AI), while no difference was observed in the posterior insula (PI). Functional connectivity analysis revealed reduced connectivity between the AI and the anterior cingulate cortex (ACC) as well as the superior frontal gyrus (SFG) in alexithymic patients. Moreover, the connection between the AI and the ACC mediated the relationship between interoception and alexithymia. These results suggested that alexithymic schizophrenia patients struggle to integrate interoceptive afferents with emotional salience, and highlighted AI's role in the interplay between interoceptive awareness and emotional articulation in alexithymic schizophrenia, suggesting a potential neurobiological pathway for targeted interventions. The research is registered with the China Clinical Trials Registry (CCTR), under the registration number ChiCTR2400080313 on January 15, 2024.