What is the distinction between Bipolar Disorder Type 2 (BD-II) and Borderline Personality Disorder (BPD)?

From the Guidelines

Bipolar Disorder Type 2 (BD-II) and Borderline Personality Disorder (BPD) are distinct conditions with different diagnostic criteria.

Key Differences

• Bipolar II Disorder is defined by the occurrence of at least one hypomanic episode and at least one depressive episode 1.
• Borderline Personality Disorder, on the other hand, is characterized by problems in functioning of aspects of the self and/or interpersonal dysfunction, with optional specification of maladaptive personality traits such as Negative affectivity, detachment, dissociality, disinhibition, anankastia, and Borderline pattern 1.

Diagnostic Criteria

• Bipolar II Disorder requires periods of major depression and hypomania, with no full manic or mixed manic episodes 1.
• Borderline Personality Disorder is diagnosed based on a pattern of instability in interpersonal relationships, self-image, and affects, and marked impulsivity 1.

Clinical Distinctions

• Bipolar II Disorder is primarily characterized by mood episodes, whereas Borderline Personality Disorder is characterized by pervasive patterns of instability and impulsivity.
• The diagnosis of Borderline Personality Disorder in ICD-11 is further differentiated according to severity into mild, moderate, and severe, and may be specified by the presence of one or multiple maladaptive personality traits 1.

From the Research

Distinction between Bipolar Disorder Type 2 (BD-II) and Borderline Personality Disorder (BPD)

The distinction between BD-II and BPD is a common diagnostic dilemma due to their similar characteristics and co-morbidity 2, 3, 4, 5, 6.

• Key differentiating factors:
  • Family history
  • Developmental antecedents
  • Illness course
  • Phenomenological differences in mood states
  • Personality style
  • Relationship factors 2, 5
• Less differentiating factors:
  • Impulsivity
  • Neuropsychological profiles
  • Gender distribution
  • Comorbidity
  • Treatment response 2, 3, 5
• Similarities:
  • Affective instability
  • Impulsivity
  • Alterations in the limbic system
  • Heritability
  • Alterations in the dopaminergic and serotonergic system 3, 4
• Differences in symptoms:
  • Patients with BPD reported higher levels of impulsiveness and hostility
  • Patients with BPD reported higher levels of cognitive and anxiety-related symptoms
  • Different types of impulsivity in the two disorders 3
• Neuroanatomy:
  • Increase in size of the amygdala in BD
  • Decrease in size of the amygdala in BPD 4
• Treatment:
  • Antidepressants are considered effective in BPD
  • Mood stabilizers are the main treatment of choice in BD 4