Five factors describe most of the acute mood episodes in bipolar I disorders

Bipolar disorder is characterized by the alternation of manic, depressive and mixed episodes. The nature of mixed mood episodes is still a matter of controversy amongst experts. Currently, the approach to this syndrome is mainly categorical and very restrictive. Mood episodes tend to cluster together within different symptom complexes, which can co-exist in individual patients. This approach is termed dimensional or factorial. While the factor structure of scales assessing schizophrenia has been thoroughly investigated, the factor-structure of bipolar mood episodes has not been studied yet.

Investigators from the Bipolar Disorders Programme at IDIBAPS - Hospital Clínic published recently in the Journal of Affective Disorders (1) a dimensional analysis of the structure of bipolar episodes aimed at identifying a factor deconstructing mixed episodes. Dr. Eduard Vieta and Dr. Francesc Colom are the last authors of the article, while Dr. Isabella Pacchiarotti is the first one. The team led by Dr. Vieta is an influential international group, as reflected in the fact that he participated in the Editorial commenting the update of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) in The American Journal of Psychiatry (2). According to Nature (3), this update is one of the 10 key findings and events that may emerge in 2013.

In this work, 187 consecutive bipolar I inpatients hospitalized at Hospital Clínic of Barcelona for depressive, manic or mixed acute mood episodes underwent a standardized assessment. The analysis of the this data revealed five significant factors corresponding to "psychosis", "euphoric mania", "mixity", "dysphoria" and "inhibited depression". Thus the factor-structure of an acute episode of any type is pentafactorial. Each factor represents a major clinical dimension of different symptom sets that may be present across different mood episodes of bipolar illness.

The purpose of the dimensional approach to bipolar disorder is not simply descriptive, but aims at improving its treatment and outcome. In fact, the new results should prompt reconsideration of proposals for DSM-5 diagnostic criteria for the mixed features specifier. DSM-5 is a new version of the reference test for psychiatric diagnosis. This is the first major update in 19 years to the standard reference guide for diagnosing mental illnesses. A recent Editorial published in The American Journal of Psychiatry, with Dr. Eduard Vieta among the authors, underlined that the new test meant progress for many patients for whom the benefits of diagnoses and treatment were previously unrealized. Nevertheless, like the IDIBAPS - Hospital Clínic researchers point in their new article, it needs constant revision to establish improved, clinically sound, real-world diagnostic criteria.

References: (1) Pacchiarotti I, Nivoli AM, Mazzarini L, Kotzalidis GD, Sani G, Koukopoulos A, Scott J, Strejilevich S, Sánchez-Moreno J, Murru A, Valentí M, Girardi P, Vieta E, Colom F. The symptom structure of bipolar acute episodes: In search for the mixing link. J Affect Disord. 2013 Feb 7. doi:pii: S0165-0327(13)00035-9. 10.1016/j.jad.2013.01.003. [Epub ahead of print]

(2) Freedman R, Lewis DA, Michels R, Pine DS, Schultz SK, Tamminga CA, Gabbard GO, Gau SS, Javitt DC, Oquendo MA, Shrout PE, Vieta E, Yager J. The initial field trials of DSM-5: new blooms and old thorns. Am J Psychiatry. 2013 Jan 1;170(1):1-5. doi: 10.1176/appi.ajp.2012.12091189.

(3) Richard Van Noorden. New year, new science. Nature looks ahead to the key findings and events that may emerge in 2013. Nature. January 2013; 493: 11