Mental disorders are overrepresented in prisoners, placing them at an increased risk of suicide. Advancing our understanding of how different mental disorders relate to distinct stages of the suicidal process—the transition from ideation to action—would provide valuable information for clinical risk assessment in this high-risk population.
Data were drawn from a representative sample of 1212 adults (1093 men) incarcerated across 13 New Zealand prisons, accounting for 14% of the national prison population. Guided by an ideation-to-action framework, three mutually exclusive groups of participants were compared on the presence of mental disorders assessed by validated DSM-IV diagnostic criteria: prisoners without any suicidal history (controls; n = 778), prisoners who thought about suicide but never made a suicide attempt (ideators; n = 187), and prisoners who experienced suicidal ideation and acted on such thoughts (attempters; n = 247).
One-third (34.6%) of participants reported a lifetime history of suicidal ideation, of whom 55.6% attempted suicide at some point (19.2% of all prisoners). Suicidal outcomes in the absence of mental disorders were rare. Whilst each disorder increased the odds of suicidal ideation (OR range 1.73–4.13) and suicide attempt (OR range 1.82–4.05) in the total sample (n = 1212), only a select subset of disorders was associated with suicide attempt among those with suicidal ideation (n = 434). Drug dependence (OR 1.65, 95% CI 1.10–2.48), alcohol dependence (OR 1.89, 95% CI 1.26–2.85), and posttraumatic stress disorder (OR 2.09, 95% CI 1.37–3.17) distinguished attempters from ideators.
Consistent with many epidemiological studies in the general population, our data suggest that most mental disorders are best conceptualized as risk factors for suicidal ideation rather than for suicide attempt. Once prisoners consider suicide, other biopsychosocial factors beyond the mere presence of mental disorders may account for the progression from thoughts to acts of suicide.