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09-01-2012 | Mental health | Article

Study results support predominant polarity in bipolar disorder


Free abstract

MedWire News: Certain demographic and clinical factors are associated with predominant polarity in patients with bipolar disorder (BD), research suggests.

"The concept of predominant polarity in BDs was proposed by Colom et alto define discrete subgroups of patients who mainly experience recurrences of depression or of mania-like episodes (manic, hypomanic, or mixed)," explain Ross Baldessarini (Harvard Medical School, Boston, Massachusetts, USA) and team.

To further investigate the concept of predominant polarity, and the association between predominant polarity and specificdemographic and clinical factors, the researchers studied 928 patients, aged at least 18 years, with type I BD from Spain, Argentina, Italy, Korea, and the USA.

Predominant polarity was defined as a ratio of depressive to manic (manic, hypomanic, or mixed) episodes of at least 2:1,and vice versa.

In total, 199 (21.4%) patients met criteria for predominantly depressive polarity and 290 (31.3%) met criteria for predominantly manic polarity.

The researchers found that patients with predominantlydepressive or manic polarity had differential patterns of demographic and clinical variables.

Specifically, factors associated with predominantly depressive versus manic polarity included electroconvulsive treatment (risk ratio=3.95), increased delay before diagnosis (RR=3.37), depression or mixed mania/depression as a first mood episode (RR=3.02), suicideattempts (RR=2.65), and Axis-II comorbidity (RR=2.41).

The researchers also note that being married and female gender were associated with predominantly depressive polarity, at RRs of 1.49and 1.24, respectively.

Predominantly manic versus depressive polarity was associated with mania or psychosis as the first mood episode (RR=3.89), drug abuse (RR=2.66), a higher education level (RR=1.53), and a family history of affectivedisorders (RR=1.37).

Including mixed states under predominantly depressive, rather than manic, polarity significantly increased the risk ratio for suicide, the researchers observe.

Baldessariniand team conclude in the journal Acta Psychiatrica Scandinavica: "The present findings support and extend the proposal that patients diagnosed by DSM-IV criteria with type-I BD can usefully be subdivided by predominant-polarity of recurrent major episodes, based on at least a two-fold excess of one polarity type."

They add: "Subtyping by predominant polarity may have value for future research as well as prognostic and potential therapeutic clinical implications."

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012

By Mark Cowen

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