The case records of 450 patients were studied and classified into five previously defined diagnostic groups: Affective Psychosis, Senile Psychosis, Late Paraphrenia, Acute Confusion and Arteriosclerotic Psychosis. Affective Psychosis accounted for over half the cases in the total material. Follow up studies showed that at six months and two years after admission each of the five disorders is characterized by a distinctive pattern of outcome as described by the proportion of patients dead, in hospital and out of hospital.
Examination of differences in pattern of outcome between specific groups provides strong confirmation for hypotheses suggesting that affective psychosis, late paraphrenia and acute confusion were each entities largely independent of the two main causes of progressive dementia in old age: senile and arteriosclerotic psychosis. The relevant differences between the groups were largely independent of differences in age distribution.
There is some evidence to suggest that the findings may have a bearing upon the problems of old age mental disorder faced by hospitals in other parts of this country.
The overlap between the senile-arteriosclerotic group on the one hand and the affective paraphrenic group on the other was relatively small. But if all kinds of affective disturbance are reckoned, their incidence in arteriosclerotic psychosis is greater than is likely to be accountable in terms of fortuitous coincidence.
Problems for further study are discussed. Investigations into the differences between and within the groups might lead to the identification of factors of practical or aetiological significance.