Reconsidering the association between psychosis and suicide: a suicidal drive hypothesis

Suicidal ideation/behaviour (SIB) and psychosis are highly associated phenomena. We propose that psychosis, for some, may be consequential to SIB. More specifically we hypothesise that psychosis may serve to externalise internally generated and self-directed threat among those experiencing SIB. Using prospective data from a Danish population cohort, we first sought to test the temporal occurrence of suicidal behaviour and psychotic disorder. Next, using cross-sectional epidemiological survey data (UK), we sought to demonstrate that psychotic experiences (PEs) were more commonly reported by those who experienced SIB and that the strength of the association varied according to (i) SIB recency and (ii) severity. Chi-square comparison tests on the Danish data revealed that suicidal behaviour was statistically more likely to precede (41.4%) rather than follow psychotic disorder (20.7%). Regression analyses of the UK data indicated that individuals who thought about suicide in their lifetime were up to eight times more likely to experience specific PEs while those who thought about and attempted suicide in their lifetime and in the year of assessment were up to 48 times more likely to experience PEs, compared to SIB free members of the population. The findings provide preliminary support for a novel suicidal drive hypothesis for psychosis.