Diagnosis and classification of functional psychoses

Four main groups of functional psychoses have been recognised since the early years of the century: schizophrenic and affective psychoses; acute psychoses of good prognosis; and chronic paranoid psychoses. The air of permanence and stability is misleading. None of these four groupings, or of the individual psychoses included within them, has been clearly demonstrated to be a disease entity'. All are still defined by their clinical syndromes and these syndromes appear to merge insensibly into one another and into other syndromes in the domain of neurotic illness and personality disorder. As a result it is not clear where the boundaries should be drawn. For most of them, therefore, several different alternative operational definitions are in competition and until aetiology is better understood there will be no satisfactory way of choosing between these. The schizophrenic and affective psychoses have been studied much more extensively than the other two groups, and both appear to ′breed true′. Even so it is still uncertain whether they are wholly independent disorders.