The detailed case notes of all in-patients suffering from depressive psychosis who were admitted to the Professorial Unit of the Maudsley Hospital between January 1st 1956 to December 31st 1959 inclusive were examined.
Of the 398 cases 31 per cent. had obsessions, 64 per cent. did not, and 5 per cent. showed transition of obsessions into delusions. The groups did not differ except for the following factors.
Depressives with obsessions attempted suicide 6½ times less frequently than depressives without obsessions or the obsession-delusion transition group.
Obsessional personalities taken as a group, and cases with frank premorbid obsessions, had half the overall suicidal attempt rate.
Depressives with obsessions compared to those without have twice as many obsessional personalities, ten times as many frank premorbid obsessions, and more obsessional personalities in their parents and siblings.
Obsessions occurred five times more often in the previous depressions of depressives with obsessions than in the previous attacks of depressives without obsessions.
Depressives with obsessions are more likely to exhibit self-reproach, diurnality of depressive symptoms and depersonalization than depressives without obsessions.
It is concluded that obsessions are common in the course of depressive psychosis, and that they are based on the activation of pre-morbid traits. They appear to have a marked protective effect against suicidal attempts, and this effect appears to depend on the obsession being phenomenologically an obsession.