Stress sensitivity, negative affect, and functioning in an early psychosis clinic.

Persons with psychotic disorders frequently exhibit stress sensitivity (SS), a low tolerance for everyday stresses, often manifesting as negative affect (NA), and frequently associated with poor functional outcome. To parse the relative contributions of SS and NA on functioning, we analyzed real-world data from consecutive evaluations in an early psychosis clinic, comparing a specific measure of stress sensitivity, the Psychological Stress Index, 9-item (PSI-9), with the Patient Health Questionnaire (PHQ-9), a measure of depressive NA, on the Work and Social Adjustment Scale (WSAS). A structural equation modeling framework tested the relationship between PSI-9, PHQ-9, and perceived functioning (WSAS), testing the hypothesis that the PSI-9 would predict functioning over and above the PHQ-9. The sample consisted of 103 patients, of whom 61 had a primary psychosis diagnosis. The PSI-9, PHQ-9 and WSAS scales were highly intercorrelated (r's 0.55-0.62). The primary model showed partial mediation of the relationship of PSI-9 with WSAS by PHQ-9 scores, as predicted. Follow-up models conducted separately for patients with and without a primary psychosis diagnoses showed that this relationship existed in both groups. Sex, entered as a co-variate in the models, did not affect the relationships. In exploratory models examining the effects of early childhood adversity, the Adverse Childhood Experiences scale, was positively related to PSI-9 scores, but only in the psychosis group. In conclusion, the PSI-9 measures SS, a phenotype important for subjective sense of functioning, over and above depressive symptoms rated on the PHQ-9, identifying a target for interventions addressing SS.