|
|
Letters to the Editor Borderline Personality Disorder Comorbidity in Early- and Late-Onset Bipolar II Disorder Dear Editor: Early-onset (EO) and late-onset (LO) mood disorders may have different etiology, clinical picture, family history, outcome, and treatment response (1,2). EO (that is, before age 21 years) and LO bipolar II disorder are understudied (3). Borderline personality disorder (BPD) is a severe disorder, and BPD comorbidity would suggest bad bipolar II outcome. I report a study that investigated whether EO bipolar II disorder had more BPD than LO bipolar II disorder, which would support EO and LO bipolar II subtyping. Methods The study was conducted by a senior clinical research psychiatrist (see Benazzi F on Medline) in his outpatient private practice. In Italy, this setting is more representative of patients with bipolar disorder because, after the family doctor, private practice is the first or second line of treatment for mood disorders. Patients with the most severe mood disorders are treated in the national psychiatric health service or in university centers (3,4). I interviewed a consecutive sample of 78 outpatients with bipolar II disorder who presented for major depressive episode (MDE) treatment over 10 months. I used the Structured Clinical Interview for DSM-IV Axis I Disorders-Clinician Version (SCID-CV) (5) and Axis II Personality Disorders (SCID-II) (6). I fully explained the procedure and obtained informed consent. Often, family members or close friends supplemented clinical information during the interview. EO-LO age cutoff was the median age at onset of the first MDE, because the median age at onset was generally used as the cutoff in mixed age samples (7). Means were compared using Student’s t-test, and frequencies with Fisher’s exact test (STATA 5) (8). Two-tailed P-values were < 0.05. Results Sample features were as follows: female sex, 58.9%; mean age, 39.5 years (SD 14.8); mean age at onset, 24.4 years (SD 12.6); and median age at onset, 21 years. BPD was present in 11.5% of the subjects (n = 9; women, n = 7). Mean (SD) ages at onset of bipolar II disorder with BPD, compared with bipolar II disorder without BPD, were 15.3 (3.2) years vs 25.7 (12.9) years (t = 2.3, df = 76, P = 0.019). Of the patients with EO bipolar II disorder (n = 38), 8 had BPD, and of the patients with LO bipolar II disorder (n = 40), 1 had BPD (2-tailed Fisher’s exact test, P = 0.013). Discussion Patients with bipolar II disorder and BPD had significantly lower age
at onset than those with bipolar II disorder without BPD, and those with
EO bipolar II disorder had significantly more BPD than those without LO
bipolar II disorder. Because BPD is a severe disorder, these findings
suggest that EO bipolar II disorder may have a worse outcome than LO bipolar
II disorder. This supports the subtyping of bipolar II disorder according
to age at onset. Age at onset has been reported as significantly lower
in patients with bipolar II disorder and different personality disorders
than in those with bipolar II disorder without personality disorders (9).
This study’s small sample of patients with bipolar II disorder and
BPD limits the findings’ validity. It needs replication in larger
samples: in primary care psychiatry, the prevalence of BPD in patients
with bipolar II disorder is low (4,9)
1. McMahon FJ, Stine C, Chase GA, Meyers DA, Simpson SG,
Depaulo JR. Influence of clinical subtype, sex, and lineality on age at
onset of major depressive disorder in a family sample. Am J Psychiatry
1994;151:210–5. Franco Benazzi, MD
|
