Benazzi F. Does age at onset support a dimensional relationship between Bipolar II disorder and major depressive disorder?
World J Biol Psychiatry 2007;
8:105-11. [PMID:
17455103 DOI:
10.1080/15622970601042500]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The current categorical splitting of bipolar and depressive disorders has been questioned. Age at onset is an important variable used to support such a division. Study aim was to assess the distribution of age at onset between bipolar II disorder (BP-II) and major depressive disorder (MDD), and onset age-bipolar family history, onset age-BP-II diagnosis dose-response relationships. No bi-modal distribution and no presence of dose-response relationships would not support a categorical distinction between BP-II and MDD. Consecutive 389 BP-II and 261 MDD major depressive episode (MDE) outpatients were interviewed with the DSM-IV Structured Clinical Interview and the Family History Screen, by a mood specialist psychiatrist in a private practice. Age at onset was defined as age at onset of the first MDE. Distribution of age at onset between BP-II and MDD was studied by Kernel density estimate and histogram methods, dose-response relationships by ROC analysis. BP-II, versus MDD, had significantly lower age at onset, more recurrences, and more bipolar family history. Kernel density estimate and histogram distributions of age at onset showed no bi-modality. Likelihood ratios between age at onset and bipolar family history loading, and between age at onset and BP-II diagnosis, showed dose-response relationships. The bi-modality and dose-response approaches, versus classic diagnostic validators, seem to support a dimensional relationship between BP-II and MDD.
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