Personality disorders (PD) and Affective temperaments (AT) have been considered vulnerability factors for the development of mood disorder (MD).

To study the simultaneous presence of PD and AT in patients with DU and differences between unipolar depression (DD) and bipolar disorder BD.

An observational study was conducted. Patients were administered the Temperament Evaluation of Memphis, Pisa, Paris and San Diego questionnaire (TEMPS-A) for AT and the Structured Clinical Interview for DSM IV Axis II Disorders (SCID-II) for PD. The interrelationships of the different PD and AT were studied by factor analysis (principal component analysis, PCA) (orthogonal rotation, Varimax).

Participants were 156 adult patients with MD, 37.1% with DD and 62.9% with BD. DD patients presented with significantly more paranoid PD (P = 0.009), depressive (P = 0.029), anxious (P = 0.009) and irritable temperament (P = 0.006) compared to BD. PCA results showed four significant factors, explaining the 63.1% of total variance, corresponding to four potential groups of patients with specific PD and AT associations.

The comorbidity between MD and PD and AT may differentiate DD from BD. Specific patterns of comorbidity may be useful as they may substantially influence the course of the mood disorders and how patients respond to treatment.

The authors have not supplied their declaration of competing interest.