Axis II comorbidity in euthymic bipolar disorder patients: no differences between bipolar I and II subtypes

Area of Science:

• Psychiatry
• Clinical Psychology
• Neuroscience

Background:

• Bipolar disorder type II (BDII) has been historically viewed as less severe than bipolar disorder type I (BDI) based on symptom intensity.
• Longitudinal studies suggest BDII may be more chronic and impairing than previously thought.
• Limited research exists on Axis II comorbidity differences between bipolar subtypes, especially in sustained euthymic states.

Purpose of the Study:

• To investigate and compare the rates of Axis II (personality disorder) comorbidity in euthymic patients with BDI versus BDII.
• To determine if BDII is indeed a milder form of bipolar disorder concerning personality disorder comorbidity.

Main Methods:

• 186 bipolar disorder patients (71 BDI, 115 BDII) meeting DSM-IV criteria were enrolled.
• All participants were euthymic for at least two months, confirmed by HAM-D (<8) and YMRS (<6) scores.
• Axis II comorbidity was assessed using the Structured Clinical Interview for DSM-IV Axis II Personality Disorders (SCID-II).

Main Results:

• The overall prevalence of at least one personality disorder was high (42.5%) across all bipolar subjects.
• No significant differences in the rates of any specific personality disorder were found between BDI (43.7%) and BDII (41.7%) groups.
• These findings indicate comparable Axis II comorbidity burdens between the two bipolar disorder subtypes.

Conclusions:

• The study confirms high rates of personality disorder comorbidity in bipolar disorder patients.
• Evidence suggests that BDII is as severe as BDI concerning Axis II comorbidity.
• Limitations include reliance on self-report for personality disorders and a sample from a tertiary center.