Psychopathologic correlates of suicidal ideation in major depressive outpatients: is it all due to unrecognized (bipolar) depressive mixed states?

BACKGROUND: Recent transatlantic concern about suicidality in patients receiving antidepressants prompted us to examine the psychopathologic correlates of suicidal ideation occurring in clinically depressed patients.
METHODS: The study sample, which consisted of 644 consecutive major depressive outpatients, of which 58.0% had bipolar II disorder (BP-II), was systematically interviewed with the SCID, in order to delineate the diagnostic and psychopathologic correlates of suicidal ideation.
RESULTS: Such ideation, which was present in 49.5% [and favoring BP-II vs. major depressive disorder (MDD)] at an odds ratio (OR) of 1.3 (95% confidence interval = 0.98-1.8), was clinically significantly associated with depressive mixed state (racing/crowded thoughts and psychomotor agitation/activation during index depression), mood lability, decreased self-esteem, anorexia, as well as melancholic and psychotic features. Multiple logistic regression of suicidal ideation versus depressive symptoms and intradepressive excitatory symptoms revealed that decreased self-esteem (OR = 3.3), racing/crowded thoughts (OR = 1.5), and psychomotor agitation/activation (OR = 1.4) were independent and clinically significant correlates of suicidal ideation, irrespective of depression severity. DISCUSSION: From a psychopathologic standpoint, suicidality might be conferred by a combination of both the excited (mixed) depressive and agitated (melancholic) clusters. Trait mood lability appears to favor the genesis of these affective clusters. Within the framework of Kraepelinian psychiatry, both clusters represent depressive mixed states. Given that such states are more prevalent in BP-II, our data provide a possible explanation for the greater suicidality in BP-II patients reported in the literature. In light of the higher odds of suicidal ideation in BP-II versus MDD patients, we hypothesize that the higher prevalence of mental and psychomotor activation in BP-II might be one factor among others that favors the greater likelihood of the transition from suicidal ideation to suicidal action in BP-II. Our analyses delineate a mixed depressive substrate at risk for suicidality. To what extent, if any, antidepressant monotherapy might contribute to the genesis of such states and/or suicidality cannot be answered with the methodology of the present study.