Basic self-disturbance in adolescents at risk of psychosis: temporal stability investigated by the experience sampling method in a mixed method study.

Background: Basic self-disturbance (BSD), also called anomalous self-experiences (ASEs), are core phenotypic markers for schizophrenia spectrum disorders and a prepsychotic vulnerability marker considered to be temporally stable (trait-phenomenon). Studies of BSD in children and adolescents are lacking.

Objective: To be clinically useful, we need to know more about the characteristics and temporal development of BSD in prepsychotic phases.

Method: This study used a smartphone application measuring the occurrence and subjective intensity of ASEs in the daily life of 27 help-seeking adolescents (12-18 years) repeatedly over a period of 6 months. A total of 5223 unique application-reports based on individually selected and verbatim descriptions of personal core ASEs were analysed by mixed methods.

Findings: The intensity of ASEs, within subjects and between subjects and irrespective of time intervals or baseline scores obtained by the Examination of Anomalous Self-Experience (EASE) were relatively stable with a mean variability of 1.25 (0.4) SD. Participants with low EASE total scores at baseline had a significantly lower score on ASE intensity than those with high baseline EASE total scores at baseline (mean 2.42 vs 3.42, p=0.046).

Conclusion and clinical implications: In this study, ASEs were not reported as essentially fluctuating experiences but as almost constantly present, demonstrating BSD as a mainly trait phenomenon in prepsychotic phases in persons under the age of 18. Considering the continuous experience of BSD and its predictive value for psychosis development, ASEs should be targeted and monitored to the same extent as other prepsychotic features.