Late-onset paranoid psychosis as a distinct clinicopathologic entity: magnetic resonance imaging data in elderly patients with paranoid psychosis of late onset and schizophrenia of early onset.

Objective: The aim of this study is to equalize the influence of age-related changes and to test the hypothesis that specific structural brain changes are mediating the development of unique clinical features in late-onset paranoid psychosis (LOPP).

Background: Findings of unique white matter lesions have been recently described in patients with LOPP. These findings have not been consistent, however, when age-matched normal subjects have been used as a control group.

Method: Magnetic resonance imaging data were compared in 13 patients with LOPP, mean age 66.33, and 35 elderly patients with early-onset paranoid schizophrenia (PSCH), mean age 63.89. Patients in the LOPP group differed from the PSCH group by the mild degree or absence of negative symptoms, the absence of formal thought disorders, and by prevalence of female patients.

Results: Analysis of the magnetic resonance imaging data revealed statistically significant differences between the LOPP and PSCH groups. White matter hyperintensity was almost threefold more frequent in LOPP than in PSCH groups, 69.2% versus 22.9% respectively. Ventricular enlargement and cortical atrophy were more frequent in the PSCH group, reaching, for moderate to severe abnormalities, 28.6% for ventricular enlargement and 22.9% for cortical atrophy; moderate to severe abnormalities were absent in all 13 patients of the LOPP group.

Conclusions: These data point to the possibility that late-onset paranoid psychosis is a distinct clinicopathological entity, with white matter hyperintensity mediating the development of LOPP in a significant percentage of the cases. The vascular origin of white matter lesions in LOPP is suggested.