Self-reported interoceptive sensitivity and heartbeat task performance in psychotic patients and healthy controls: evidence from a source monitoring study

Interoception is the process by which the nervous system senses and integrates signals from within the body, generating models of internal physiological states that contribute to self-representation. In this work, we investigated two dimensions of interoception: interoceptive sensitivity, which refers to the individual’s subjective beliefs about internal bodily sensations (self-reported perception), using the MAIA (Multidimensional Assessment of Interoceptive Awareness); interoceptive accuracy, referring to an individual’s capacity to detect and accurately report internal bodily signals (independent of subjective beliefs or emotions), using a Heartbeat Counting Task. This research aimed to investigate interoceptive sensitivity and interoceptive accuracy in 57 patients with a diagnosis of any DSM-5 psychotic disorder (PSY), comparing them with 57 healthy controls (HC) matched for age and gender.

Inclusion criteria were age 18-60 years, fluency in Italian and IQ ≥ 80 (Wechsler Abbreviated Scale of Intelligence – Second Edition, WASI-II). For patients, exclusion criteria were intellectual disability or a neurological condition underlying psychotic symptoms; for controls, were any lifetime psychiatric diagnosis or current/past use of psychiatric medication.

Statistical analyses were performed using SPSS-31. Mean performance on the Heartbeat Task and scores on the different MAIA subscales were compared between the two groups (HC vs. PSY) using an independent-samples t-test. As a secondary aim, patients were divided into those with schizophrenia or schizoaffective disorder (PSY-S, n = 30) and those with other psychotic disorders (PSY-O, n = 27). Then, Heartbeat Task performance and MAIA subscale scores were compared among HC and the two clinical subgroups using ANOVA. Finally, correlations between each MAIA subscale score and Heartbeat Task performance were explored in all groups and subgroups.

Regarding the Heartbeat Task, t-tests showed significantly greater accuracy in HC compared to PSY (mean = 0.6345 vs. 0.4217, p = 0.001), while concerning the MAIA subscales, significantly different values (HC vs. PSY) were found for the dimensions Noticing (mean = 3.5402 vs. 3.1360, p = 0.031), Attention Regulation (mean = 3.3948 vs. 2.6993, p < 0.001), Self-Regulation (mean = 3.2768 vs. 2.5870, p < 0.001), and Trusting (mean = 3.8909 vs. 3.2223, p = 0.003), whereas no significant differences emerged for the remaining domains. Overall, no significant differences emerged between the patient subgroups. Similarly, no significant correlations were detected between MAIA subscale score and Heartbeat Task performance in all groups and subgroups.

The main limitations concern the sample size and the lack of differentiation among clinical phases of psychotic disorders. The present findings indicate that psychotic patients show significantly reduced interoceptive accuracy, as measured by the Heartbeat Task, compared with healthy controls. Conversely, differences in interoceptive sensitivity, as assessed by the MAIA, were significant only for selected subdomains and showed low magnitude and mixed results. These results highlight the potential importance of interoceptive processes in psychotic disorders and support the presence of different mechanisms regulating interoceptive accuracy and sensitivity. Additional studies are required to better delineate interoceptive dimensions and to establish their applicability and utility in clinical practice.

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