Suicidal ideation and the subjective aspects of depression

Background: Suicidal ideation is common in depression, but only moderately related to depression severity - in part because certain clusters of symptoms, such as those related to core mood disturbance, have a differential relationship to suicidal thinking.

Methods: 400 medication free participants with current major depression were assessed with either or both the Hamilton Depression Rating Scale (HDRS, n=396) and Beck Depression Inventory (BDI, n=366), and the Scale for Suicide Ideation (SSI). Depression rating scales were decomposed into symptoms clusters previously reported (Grunebaum et al., 2005), in order to evaluate their association to suicidal thinking.

Results: Correlations between overall depression severity ratings and the measure of suicidal ideation were modest, and reduced when specific items assessing suicidal thinking on these depression scales were removed. Symptom clusters assessing Psychic Depression (HDRS), Subjective Depression (BDI), and Self-Blame (BDI) were the strongest correlates of suicidal ideation; other somatic and vegetative symptoms had little or no association to suicidal ideation. Severity of these symptom clusters effectively discriminated those with (SSI>0) and without (SSI=0) ideation; severity of these symptom clusters was less strongly associated with the severity of ideation once ideation was present.

Limitations: This is a cross-sectional study, and the dynamic relationship between changes in the severity of various depressive symptoms and change in suicidal thinking remains to be explored.

Conclusions: Depression severity is moderately associated with suicidal ideation, and accounted for primarily by core mood disturbance symptoms and self-punitive thinking. These associations may explain why suicide risk might remain high during treatment even though somatic and vegetative symptoms improve.