Subjective space and time experience in schizophrenia spectrum disorders and mood disorders: Psychometric properties and clinical correlates of the semi-structured STEP interview.

BACKGROUND

Altered experiences of space and time are core features of schizophrenia spectrum disorders (SSD) and mood disorders (MOD). In this study, we investigated whether patients with SSD and MOD exhibit shared or distinct patterns of subjective spatiotemporal experience.

METHODS

We examined 62 ICD-11 patients (33 SSD, 29 MOD) using the Scale for Space and Time Experience in Psychosis (STEP). We also administered the Positive and Negative Syndrome Scale (PANSS), the Montgomery-Åsberg Depression Rating Scale (MADRS), the Personal and Social Performance Scale (PSP), and the Trail Making Test B (TMTB). Different statistical analyses including linear discriminant analysis (LDA) were used to compare groups, assess STEP's discriminatory power, and explore associations with demographic and clinical characteristics.

RESULTS

STEP showed high internal consistency (Cronbach's α = 0.89 for 7-day and α = 0.93 for lifetime scores). Lifetime, but not 7-day, STEP scores differed significantly between SSD and MOD patients (multivariate group effect: p = 0.004). SSD patients reported more pronounced disturbances in time fragmentation, future premonitions, time synthesis, and spatial disorientation, whereas MOD patients more frequently reported a past-dominated experience of time and reduced intentionality toward the external world. Furthermore, 7-day and lifetime STEP scores were strongly correlated in SSD (ρ = 0.619, p < 0.001) and moderately correlated in MOD (ρ = 0.378, p = 0.043).

CONCLUSION

The STEP interview provides a reliable assessment of subjective disturbances in space and time experience. Distinct spatiotemporal profiles were identified in SSD and MOD, particularly in lifetime assessments. These findings support the relevance of subjective spatiotemporal experience as a transdiagnostic dimension of psychopathology while highlighting disorder-specific differences that warrant further longitudinal investigation.