Late-onset schizophrenia versus paranoid psychoses: a valid diagnostic distinction?

The authors tested the validity of the diagnostic distinction between schizophrenia and delusional disorder of late onset. Authors examined hospital case registers. A clear distinction between these diagnostic groups is not possible, irrespective of whether a descriptive, predictive, or construct-based approach is taken. There is a relatively high overlap between the two groups. Clinical diagnosis seems to be influenced more by the age of the patients than by symptomatology. Furthermore, the slight differences observed in symptomatology can partly be explained by "pathoplastic" factors that influence symptomatology, such as age, sex, previous treatment, or somatic comorbidity. Since clear and etiologically meaningful differentiation between these diagnostic categories is not possible, they should not be separated by artificial diagnostic criteria for research purposes. Rather, the whole "schizo-paranoid" spectrum should always be analyzed. As long as classification is based on differences in symptomatology, the influences of pathoplastic factors should be taken into account.