Delusion occupies an important position in the diagnosis and treatment of patients with psychoses. Although Karl Jaspers’ concept of the primary delusion (PD) is a key hypothesis in descriptive phenomenology concerning the primordial experience of delusion, to our knowledge it has not been verified in empirical studies of patients with psychosis, and the relationship between PDs and fully developed delusions remains unclear.
The subjects were 108 psychiatric patients diagnosed with DSM-IV schizophrenia or schizoaffective disorder who had persisting delusions. This investigation used a newly devised semi-structured interview, the Delusion and its Origin Assessment Interview (DOAI), and the Positive and Negative Syndrome Scale. PDs enquired about in the DOAI were delusional perception, delusional memory, delusional mood, and delusional intuition. Associations of PDs with delusion themes and delusion features extracted from DOAI items by factor analysis were examined using correlational and MANCOVA regression analyses. Reliability studies of the DOAI were also conducted.
The reliability and correlation analyses suggested robust psychometric properties of the DOAI. The percentages of subjects reporting PD phenomena as delusion origins and currently present were 93% and 84%, respectively. MANCOVA revealed several significant associations, including between delusional perception and delusional mood and persecutory themes, between delusional intuition and grandiose delusions, and between delusional perception and intuition and systematization of delusions.
This study demonstrates that PDs can be considered as principal origins of delusions by subjects with psychosis, and have meaningful connections with the characteristics of their fully developed delusions. The associations between PDs and delusion characteristics can be interpreted in terms of progression processes of delusions, which are seen as intensification and generalization of cognitive and affective pathologies in PDs. The findings are also consistent with the neurobiological hypothesis that aberrant salience attribution to stimuli, as in PDs, is the primary phenomenon caused by abnormal dopamine system regulation. Further studies are needed to clarify delusion progression processes relating to PDs and to substantiate their clinical meanings.