The aim of the present study was to thoroughly investigate the existing comorbidity between Axis II and Bipolar Disorder (BD) pointing out as well the meaningful existing comorbidity between Personality Disorders and Cyclothymia.

A study group composed of 70 patients affected by Bipolar Disorder (Type I, Type II, and Cyclothymia) was enrolled at the Bipolar Disorders Unit of the Catholic University of the Sacred Heart of Rome. Axis I diagnosis was made by SCID-I; Axis II diagnosis was made by SCID-II.

In a sample of 70 patients in euthymic phase, 39 patients (55.7%) showed comorbidity with Axis II Disorders. Clusters were represented as follows: 2 patients (5.1%) fell within cluster A; 24 patients (61.5%) within cluster B; 9 patients (23%) within cluster C; and 4 patients (10.4%) turned out to be affected by NAS Personality Disorders. On the whole 39 patients - 24 patients (61.5%) affected by BD I, 6 patients (15.3%) affected by BD II, and 9 patients (23.0%) affected by Cyclothymia were found to have comorbidity with Axis II Disorders. Besides, in our sample there was a significant comorbidity between Cyclothymia and Personality Disorders.

More than half of patients (55.7%) showed comorbidity with Axis II Disorders. Moreover most of patients turned out to be affected by Personality Disorders falling within cluster B while 23% of Cyclothymic patients were found to have comorbidity with Axis II Disorders.