According to clinical models of personality, patients with dissociative identity disorder (DID) who have experienced demonic possession (psychiatric possession syndrome or PPS) may present two profiles: the schizo-paranoid profile (characteristic of psychotic spectrum disorder or PSD) and the hysteroid-histrionic profile (characteristic of affective disorders). The present study aimed to examine the clinical and statistical evidence of these phenotypic personality structures in patients with PPS and DID (with and without PSD).

The design of this investigation was based on structural equation modeling. A total of 303 patients were diagnosed with DID without psychosis and 306 were diagnosed with DID with PSD; the diagnosis was made by clinical professionals who collaborated on this research and conducted the assessment tests. All patients completed clinical questionnaires on their personality structures, and dissociation level was also measured. The physician-psychiatrist assessed each patient using the Psychiatric Possession Syndrome Checklist (PPS-C), a new hetero-applied questionnaire on the symptomatic intensity of PPS.

The results led to the conclusion that both personality structures were 65 %–66 % predictive of possession syndrome. Dissociative symptoms attributable to DID modulated the PPS variance by 21 % to 26 %. Validity evidence has been obtained for the combined phenotypic personality model that integrates DID and PSD structures.

We discuss the psychopathological and therapeutic implications of the analysis on the dissociative mechanisms involved in each personality phenotype. We also provide a graphical summary of the PPS symptoms, organized into a normalized distribution, which may prove useful for professional practice. Additionally, we present potential clinical scores from the PPS-C.