Organic factors and the clinical features of late paranoid psychosis: a comparison with Alzheimer's disease and normal ageing

Abstract

The diagnostic allocation and aetiological basis of paranoid psychoses with late onset is controversial. We examined the clinical features of patients with a diagnosis of paranoid psychosis and we compared their cranial computed tomography (CT) scans and electroencephalographic (EEG) recordings with findings from matched samples of patients with Alzheimer's disease and non-demented elderly controls. During a 5-year period, 81 patients (15 men and 66 women) with a diagnosis of paranoid psychosis and onset after age 50 were referred to our Institute. They represent 5.4% of the patients older than 50 admitted during the same period. More than half of these patients had first-rank symptoms. The ventricles, anterior and sylvian fissures of the paranoid group were larger than in non-demented controls but smaller than in Alzheimer's disease. The posterior dominant alpha EEG rhythm was slower than in normal aging and faster than in Alzheimer's dementia. If paranoid patients with first-rank symptoms were distinguished from the ones without, the former had less severe brain atrophy and faster posterior dominant rhythm, although they received higher doses of neuroleptics. This could be explained by the existence of at least 2 subgroups of late paranoid psychosis: late-onset schizophrenia and organic paranoid syndrome, the former characterized by first-rank symptoms and less severe brain atrophy, the latter by more severe EEG and CT scan changes with a closer resemblance to degenerative brain disease.