Kurt Schneider defined 'first rank symptoms' (FRS) of psychosis. Previous research found two clusters of FRS: 'loss of ego bound' symptoms (e.g., delusions of external control) and auditory hallucinations (e.g, commenting voices). In patients with a psychosis we investigated whether FRS are a separate cluster within the group of positive symptoms, consisting of two underlying factors that are stable over time. We conducted a principal axis factor analysis (PAF) at baseline (n = 857) and a confirmative factor analysis (CFA) at three-year follow-up (n = 414) on (FRS) symptom score. Also, we investigated the stability of the two-factor structure of FRS over the interval. PAF on 16 items representing positive symptoms at baseline revealed two factors with eigenvalues > 1. FRS-delusional self experience (thought withdrawal, thought broadcasting, thought insertion, and beliefs that impulses and/or actions are controlled by an outside force) clustered in one factor and FRS-auditory hallucinations (auditory hallucinations, conversational voices, and voices commenting on one's actions) in the second factor. Furthermore, CFA on the FRS-items at follow-up confirmed the two-factor structure of FRS. FRS delusional self experience and FRS-auditory hallucinations at baseline were significantly associated with the same factors at three-year follow-up (FRS-delusional self experience: r = 0.38; FRS-auditory hallucinations r = 0.47). Hence, our findings confirm a two-factor structure of first rank symptoms, i.e. FRS-delusional self experience and FRS-auditory hallucinations, with a moderate to large internal coherence within each factor and relative stability over time. Future studies on self-processes may contribute to our understanding of the pathophysiology of first rank symptoms.
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