Self-reported interoception and exteroception are atypical and excessively coupled in psychosis compared to healthy controls

Although psychotic disorders are characterized by an impaired ability to discriminate internal and external worlds, the role of interoceptive and exteroceptive perceptions in determining this alteration is still unclear. This observational study aimed at investigating (a) increases/decreases in interoceptive and exteroceptive perceptions in patients with psychosis (PSY) compared to healthy controls (HC); (b) the association between interoception and exteroception in HC and PSY. Two hundred and ten HC and 72 PSY completed the Multidimensional Assessment of Interoceptive awareness (MAIA, 8 domains) and the Adolescent-Adult Sensory Profile (AASP, 4 domains). MAIA/AASP differences were evaluated with MANOVA, Kruskal-Wallis and Mann-Whitney tests. MAIA and AASP scores were correlated to quantify the interoceptive-exteroceptive coupling as Spearman's rho coefficients. Subgroup analyses were performed dividing PSY in schizophrenia/schizoaffective versus other psychosis. Compared to HC, PSY showed increased mean scores in four MAIA and two AASP domains (Bonferroni-p < 0.01). The interoceptive-exteroceptive coupling followed two correlation patterns in HC. A first pattern displayed negative correlations between MAIA not-worrying and AASP sensory sensitivity/sensation avoidance, while the second pattern highlighted positive correlations between MAIA scores and AASP sensation seeking. The two correlation patterns between HC and other-PSY subgroup were similar. However, schizophrenia/schizoaffective PSY did not show positive correlations in the second pattern, rather displaying negative correlations between MAIA scores and AASP domains related to passive behavioral responses. Correlation values were more extreme in PSY subgroups, indicating stronger interoceptive-exteroceptive coupling compared to HC. This study demonstrates that interoception and exteroception are atypical and excessively coupled in psychosis compared to the general population.Clinical Trials Registration: Protocol Number 20210003663 (Pavia, Ethical Committee IRCCS Policlinico San Matteo).