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The overwhelming evidence for a lack of diagnostic significance of Schneider's first-rank symptoms (FRS) in schizophrenia (Tandon et al. 2013) led DSM-5 and ICD-11 authors to eliminate the special diagnostic significance placed on these symptoms in previous versions of the manuals. However, Moscarelli (2020) argues that the previous data on the diagnostic value of FRS are invalid because of the lack of ‘strict compliance with Schneider's criterion for their definition’. More specifically, he argues that previous studies do not fit the phenomenological method for assessing FRS and that some ratings may have included equivocal or doubtful FRS.
Although Moscarelli notes significant methodological limitations in the literature, the article does not mention studies conducted in Schneider-oriented German centers (Koehler, Guth, & Grimm, 1977; Marneros, 1984; Marneros, Rohde, Deister, & Sakamoto, 1987) or with a rigorous assessment methodology (Peralta & Cuesta, 1999) that failed to demonstrate a diagnostic specificity of FRS. Furthermore, he does not refer to evidence indicating that FRS can be expressed along a continuum of severity (Klosterkötter, 1992; Koehler, 1979), similar to that reported for other reality-distortion symptoms (van Os, Linscott, Myin-Germeys, Delespaul, & Krabbendam, 2009). The report by Moscarelli aligns with some other recent studies that vindicate the historical, diagnostic, etiopathological, or clinical relevance of FRS (Cutting, 2015; Heinz et al., 2016; Kendler & Mishara, 2019; Malinowski et al., 2020; Picardi, 2019). Thus, a re-examination of the diagnostic and clinical validity of FRS in psychotic disorders appears to be in order. While the debate about the importance of FRS has been mainly focused on their diagnostic value, there is a paucity of empirical studies examining other validity indicators, and no studies have examined the comparative validity between FRS and other reality-distortion symptoms.
In this report, using a rigorously phenomenological approach to elicit FRS, we examined (a) the degree to which ‘unequivocally present’ FRS differentiated schizophrenia from other psychotic disorders in a large sample of subjects with the full range of ‘functional’ psychotic disorders, and (b) the comparative validity between FRS and other reality-distortion symptoms against 16 external validators. Relatedly, we were specifically interested in examining the extent to which FRS predicted the validators over and above other delusions and hallucinations, a question that, to the best of our knowledge, has not been...