The association between suicidal ideation and increased mortality from natural causes.

BACKGROUND Despite strong evidence for increased suicide mortality among individuals experiencing thoughts of suicide, the effect of suicidal ideation on increased natural mortality has not been evaluated. The present study aimed to assess whether there is excess mortality from all natural causes or from specific natural causes that is attributable to suicidal ideation. Adjustments were made for a range of demographic, mental health and physical health measures to examine evidence for specific mechanisms of the relationship. METHOD A community-based Australian cohort of 861 older adults was followed for up to 17 years. Vital status and cause of death were ascertained from a national death registry. RESULTS After adjusting for demographics, physical health and mental health, presence of suicidal ideation was associated with a 23% increase in the risk of mortality from natural causes (p=0.034). The increased mortality was largely attributable to heart disease deaths (hazard ratio=1.43, p=0.041). LIMITATIONS There was a limited number of deaths from respiratory disease or stroke, and modest rates of suicidal ideation in the cohort. Assessment of suicidal ideation was brief, while adjustment for mental health symptoms relied on non-diagnostic measures. CONCLUSIONS Although the relationship between suicidal ideation and mortality from natural causes was partly explained by physical and mental health status, thoughts of suicide independently accounted for an increased risk of mortality. Further research should examine whether this relationship is mediated by poorer health behaviours among individuals experiencing thoughts of suicide.