Somatic delusions in schizophrenia and the affective psychoses.

Background: Delusions relating to the body, a ready source of information about the immediate experiences of psychotic patients, have not been systematically studied. We attempted an account of the phenomena, looking for differences between diagnostic groupings in the type and lateralisation of such phenomena, and for evidence of localisation.

Method: Somatic delusions elicited at interview with 550 Research Diagnostic Criteria-diagnosed psychotic patients were categorised according to content, and the results were compared across diagnostic groupings.

Results: Significant differences were demonstrated, both at the level of individual delusions and in the nature and overall pattern of such delusions. There were also differences between diagnostic groups in the choice of body parts involved. Among male patients there were significant differences in laterality between the groups, with schizophrenic subjects locating abnormal phenomena principally on the left and depressive subjects on the right. A provisional taxonomy of bodily delusions was developed.

Conclusion: Phenomenological differences between the psychoses were demonstrated and the results offer some support for current hypotheses of localisation of brain dysfunction in the psychotic illnesses.