Effect of affective temperament on illness characteristics of subjects with bipolar disorder and major depressive disorder

Background: Affective temperaments represent the stable, biologically determined substrates of mood disorders. The relationship between affective temperaments and bipolar disorder (BD) or major depressive disorder (MDD) has been described. However, the strength of such relationship should be tested while considering other factors influencing the diagnosis of BD/MDD. Literature also lacks a comprehensive description of the interplay between affective temperament and characteristics of mood disorders. The aim of the present study is to address these issues. Methods: This is a multicentric observational study including 7 Italian university sites. Five-hundred-fifty-five euthymic subjects with BD/MDD were enrolled and further divided in those with hyperthymic (Hyper, N = 143), cyclothymic (Cyclo, N = 133), irritable (Irr, N = 49), dysthymic (Dysth, N = 155), and anxious (Anx N = 76) temperaments. Linear, binary, ordinal and logistic regressions were performed to assess the association between affective temperaments and i) diagnosis of BD/MDD; ii) characteristics of illness severity and course. Results: Hyper, Cyclo and Irr were more likely to be associated with BD, together with earlier age of onset and presence of a first-degree relative with BD. Anx and Dysth were more associated with MDD. Differences in association between affective temperaments and characteristics of BD/MDD were observed for hospital admissions, phase-related psychotic symptoms, length and type of depression, comorbidity and pharmacological intake. Limitations: Small sample size, cross-sectional design, recall biases. Conclusion: Specific affective temperaments were associated to certain characteristics of illness severity and course of BD or MDD. Evaluation of affective temperaments might help a deeper understanding of mood disorders.