Objective: Suicidal behaviour is often considered in the context of depression. Taking an empirical, dimensional and population-based approach, this investigation examines two issues: first, whether it is justifiable to regard suicidality as a symptom of depression or an independent construct. Second, although suicidal behaviour has been shown to decline with increasing age and differ across gender, little is known about the stability of the underlying construct across the lifespan and between genders.
Method: Data were derived from a community-based sample consisting of 7485 people aged 20-24, 40-44 or 60-64 years. Confirmatory factor analysis was used to assess the adequacy of model fit and measurement invariance across gender and then age groups.
Results: The data fitted a two-factor model of depression and suicidality better than a single-factor model. Multi-group analysis indicated strict measurement invariance for both gender and age groups, indicating no significant differences between groups in measurement model fit.
Conclusions: These analyses establish that suicidality is distinguishable from depression, although the factors are substantially correlated. Results suggest that the underlying factorial relationship between suicidality and depression appears not to vary considerably between genders or across cohorts aged 20-24, 40-44 and 60-64 years. Finally, the analyses also highlight the necessity of inventories with scales identifying symptoms of suicidality independent of depression symptoms.