Dimensional approach to delusions in psychotic depression in the elderly: factor structure and clinical correlates

The present study attempted to investigate the clinically important broader dimensions of clinical characteristics of delusions, through multivariate analysis, in a pure sample of elderly unipolar delusional depressives as well as to test their external validity against a set of demographic, anamnestic and psychopathological validators.

Fifty inpatients suffering from psychotic major depression (PMD) in the context of major depressive disorder, 60 years old or older, were assessed on the basis of SCID IV, HRSD, MMSE and by three-point ordinal scales of 12 clinical, intrinsic or relational characteristics of delusions tested for their inter-rater reliability.

Principal Component Analysis resulted in the extraction of five factors, jointly accounting for 69.7% of the total variance. The five factors were interpreted as representing the dimensions of delusional strength, acute upsetting, delusional organization, incomprehensibility and incitation to actions. Most of the factors were differentially associated with patients' demographic, anamnestic and clinical variables.

Our results overlap in part with those of another similar study in delusional depressives of all age-ranges, differing, however, in respects possibly attributable to peculiarities of elderly depressives. Overall, the findings of the present study contribute to the further elucidation of major clinical dimensions of delusions in PMD in the elderly and the testing of their external validity.