Psychopharmacology and the Classification of Functional Psychoses 

By Thomas A. Ban and Bertalan Pethö

Four-Dimensional Classification

Psychosis: Organic vs Functional

Two-Dimensional Diagnosis

        The diagnosis of functional and organic (exogenous) psychosis cannot be made within a one-dimensional model of classification. It can be made only within a two-dimensional model, because cross-sectional psychopathological symptom profiles do not suffice. They need to be supplemented with information on the form of onset and antecedent etiological event(s), e.g., biologic factors such as somatic illness or brain disease, for the interpretation of findings. The presence of somatic illness (including brain disease) immediately prior to or at the onset of psychosis, however, does not exclude the possibility that the psychosis is functional in nature. The same applies when the somatic illness and the mental disturbance do not run a parallel course (Pethö, Ban, Kelemen et al., 1984). Accepting functional and organic psychoses as end-points divides the psychotic population into two major groups and only in one of these two populations, i.e., functional psychosis, do antipsychotic drugs remain the treatment of choice. In the organic psychoses the treatment should be directed against the etiology of the disease, e.g., nicotinic acid in case of pellagra, neurosurgery in case of brain tumor.

        In the case of organic psychosis causal treatment may need to be supplemented transiently by the administration of an antipsychotic drug. The use of antipsychotics as primary treatment, within a two-dimensional model of psychiatric classification, becomes restricted to patients with the diagnosis of functional psychosis. Probably even more important is the fact that even within the functional psychoses, patients respond differentially to treatment with antipsychotic drugs. Because a differential therapeutic response is an indicator of diagnostic heterogeneity, the finding of differential therapeutic responsiveness among patients is in support of the contention that functional psychosis consists of more than one diagnostic group.