Delusion and hallucinations occur in a variety of psychiatric disorders. In the last years they have been considered multidimensional phenomena, since emotional, cognitive and action-oriented aspects were recognized. According to the cognitive model of the development of positive symptoms, emotional processes play an important role for the relationship between delusion and hallucinations. Although delusion and hallucinations often coexist, there are few empirical studies, which explore this relationship.

Aim of the study is to elucidate the relationship between delusion and hallucinations taking into consideration their multidimensionality.

Eighty-two patients with delusion and hallucinations with a schizophrenia spectrum disorder were examined. Several instruments to the exploration of delusion and hallucinations were used as the Psychotic Symptoms Rating Scales (PSYRATS), MacArthur-Maudsley Delusions Asessment Scchedule (MMDAS), Dimensions of Delusional Experience (DDE), Positive and Negative Syndrom Scale (PANSS), Brown Assessment of Beliefs Scale (BABS), Clinical Delusion Rating Scale (CDRS) and the Heidelberger Delusion Profile (HDP). The correlations between formal hallucination and delusion criteria, as well as formal hallucination criteria and delusion content were calculated. The causal relationship between delusion and hallucinations was tested through a structural equation modelling.

Correlations between delusion and hallucinations dimensions could be found, at item, subscale and scale levels. Emotional and cognitive delusion dimensions correlated significantly with hallucinations magnitude. The delusion content showed a significant influence on the occurrence and emotional dimension of hallucinations. Delusion secondary to hallucinations could only be partially confirmed.

The results confirm the complex structure of the relationship between delusion and hallucinations.