Abstract
Formal thought disorder (FTD) is classically associated with schizophrenia-spectrum disorders, but speech disorganization may also occur in other acute psychotic conditions. This study compared eight prespecified FTD phenomena between operationally defined primary and secondary psychotic disorders. In this single-center cross-sectional study, 93 adults admitted with an acute psychotic state to three psychiatric inpatient departments were classified as having primary psychotic disorders (F20/F23.2; n = 51) or secondary psychotic disorders (F06.2/F10.5/F15.5; n = 42). Eight phenomena derived from Andreasen’s descriptions were rated using study-specific 0–2 ordinal anchors. Item-level distributions were analyzed using exact tests with Benjamini–Hochberg correction and covariate-adjusted ordinal regression; composite and diagnostic-subgroup analyses were exploratory. Higher ratings in the primary group were observed for derailment, tangentiality, incoherence, neologisms, and clanging, whereas loss of goal, circumstantiality, and perseveration did not differ statistically. Adjusted models supported the same item-level pattern, and sensitivity analyses supported several principal findings. The exploratory composite was also higher in the primary group (median 10 [8–10.5] vs. 7 [6–8]; p < 0.001). These findings support cautious, descriptive phenomenon-level assessment across acute psychotic disorders but do not validate the framework as a diagnostic instrument or establish disorder-specific FTD profiles.