This study aimed to deepen the understanding of the psychological mechanisms underlying the formation and maintenance of clinical high-risk symptoms for psychosis (CHR-P) in real-life contexts. Specifically, it examined whether (i) momentary feelings of stress increase the frequency of CHR-P symptoms, or conversely, (ii) CHR-P symptoms increase the intensity of stress. Additionally, potential moderators of the relationship between stress and CHR-P symptoms were explored.

Using Ecological Momentary Assessment, 79 patients (age: 11–36; 50.6% female) recruited from an early detection center for psychosis, reported their momentary stress levels and the frequency of CHR-P symptoms eight times a day for seven days. Time series data were analyzed using residual dynamic structural equation modeling in a random intercept cross-lagged panel design, comparing differently modeled contemporaneous effects.

There was no evidence of a contemporaneous or temporal link between stress on CHR-P symptoms. However, a contemporaneous effect of CHR-P symptoms on stress was found, while the corresponding temporal effect was not significant. The severity of interview-assessed CHR-P symptoms, age, and type of CHR-P symptoms (i.e., basic symptoms vs. [attenuated] positive symptoms) did not affect the contemporaneous effect of CHR-P symptoms on stress. However, nonperceptive symptoms had a greater contemporaneous effect on stress than perceptive symptoms.

The findings suggest a greater contemporaneous impact of CHR-P symptoms on stress than vice versa. The experience of nonperceptive symptoms, in particular, may alter the appraisal of stress in daily life and represent a target for early interventions in real-time daily life (i.e., ecological momentary interventions).