Exploring the role of affective temperaments: predicting major depressive disorder in the context of borderline personality disorder.

Purpose: Major depressive disorder (MDD) is a complex condition believed to arise from a multifaceted interplay of genetic, environmental, and biological factors. In the pursuit of understanding its etiology, two elements that warrant investigation are borderline personality disorder (BPD) and affective temperaments. We aim to gain deeper insights into the mechanisms underlying this debilitating mental health condition.

Method: The dataset comprises individuals who sought assistance from psychiatry outpatient clinics for diverse reasons during the period spanning from 2018 to 2022. These individuals underwent SCID-II assessments to diagnose borderline personality disorder (BPD) and also completed the TEMPS-A temperament tests.

Results: The mean years of schooling was lower in the MDD group (p = 0.014). Two groups are compared in terms of affective temperament. Depressive (p < 0.0001), cyclothymic (p < 0.0001), anxious (p = 0.001), and irritable (p < 0.0001) temperament scores were statistically higher in the MDD group. Apart from the scale scores, the prevalence of affective temperament was evaluated and the same temperaments (depressive (p < 0.0001), cyclothymic (p < 0.0001), anxious (p = 0.001), and irritable (p < 0.0001)) were found to be significantly higher in the MDD group. Diagnosis of BPD is higher in the MDD group (p = 0.002). Binary logistic regression analysis revealed that the presence of cyclothymic temperament and marital status may be predictor factors for the development of MDD (p < 0.0001, CI: 0.001-0.121 and p = 0.002, CI: 1.550-7.172, respectively).

Conclusion: Notably, higher scores in cyclothymic temperament and experiencing loneliness have been identified as significantly associated with MDD. Interestingly, in patients with comorbid BPD-MDD, the presence of cyclothymic temperament appears to be a more critical factor than personality traits. This finding underscores the potential role of cyclothymic temperament in contributing to the co-occurrence of BPD and MDD.