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Exploring Different Models for Bipolar Disorder

My bipolar disorder went undiagnosed for years, and predictably, became more severe with time. . Without meticulous mood tracking and intentional awareness of the impairments in my life, I likely would not have been diagnosed at all.. . I am so grateful I eventually made it to the shrink’s office: medication has significantly improved my life. And my personal journey with the illness cultivated an interest in the classification of bipolar disorders; I hope that my story will help people with similar experiences to get the treatment they need.


The Diagnostic and Statistical Manual for Mental Disorders (DSM) was written by the American Psychiatric Association to provide mental health professionals, researchers, and insurance companies with a common language in conceptualizing and diagnosing mental health disorders (Gitlin & Malhi, 2020). This desk reference is currently on its fifth edition. Over time, bipolar disorder and other mental illnesses reviewed in the text have been treated with increasing complexity and comprehensiveness, with the inclusion of more detailed criteria and related disorders. In the DSM-IV, published in 1994 and directly preceding the current edition, the criteria listed for Bipolar Disorder centered on episode length and number of symptoms. These are a couple of ways to think of bipolar disorder but by no means necessarily the best. Indeed, beyond the DSM, there have historically been many ways of conceptualizing bipolar disorder.

Models for Bipolar Disorder

Historical Models

In this section, I will summarize the historical discussion around bipolar disorder, particularly as it relates to key figures, to provide a background for modern models of the illness. I rely heavily on the work of Brittany L. Mason, PhD and Gin S. Mahli, M.D.


Karl Ludwig Kahlbaum was a 19th century German psychiatrist. He placed an emphasis on the recurrence of symptoms and lifelong course of bipolar disorder, noting "mood, intellect, and behavior as the principal domains” impacted in the illness (Malhi et al, 2018). By discussing the correlation between in motion activity and cognition, Kahlbaum effectively captured the nuances of mood episodes.


Emil Kraepelin was another German psychiatrist and a contemporary of Kahlbaum’s. He argued that “mania…, melancholia and... amentia (confusional or delirious insanity)” were tied together. He also noted the “gradual transitions“ between these states, thereby acknowledging the complexity of bipolar symptoms. Mason believes that this properly captures “depressive and manic states, psychosis, mixed states, and the subdromal expressions” (Mason, 2016) of bipolar disorder. He states that “all of these [are] manifestations of a single morbid process that [is] expressed in a variety of clinical forms and that [is] linked by common temperamental and familial-genetic factors” (Akiskal & Pinto, 1999).


A third German psychiatrist, Wilhelm Weygandt, had a unique take on mixed episodes. (In a mixed episode, a person experiences symptoms of mania and depression, simultaneously or in rapid sequence.) He held that those episodes come in a wide variety and the “excitation of mania [does] not always affect mood, activity, and cognition at once, and that some domains could in fact be inhibited as in depression” (Malhi et al, 2018).

Modern Models

With that historical background out of the way, readers should now have a foundation to understand the modern models that I will now discuss. I will also offer my personal opinions on those models.


Hagop S. Akiskal, MD proposes a very particular treatment of bipolar disorder to capture the range of experiences patients have. In his paper, “The evolving bipolar spectrum: Prototypes I, II, III, and IV,” he and Olavo Pinto, M.D. describe levels of the disorder (1, 2, 2.5, 3, 3.5, and 4) through the application of case studies. Aside from Bipolar I and II, he also documents cyclothymic disorder and drug-induced bipolarity. Despite his employment of the word "spectrum," his definitions of the different types of bipolar disorder still confine symptoms to categories. While this model does effectively capture the varying presentations and etiologies of bipolar, I believe it’s restrictive. In its ranking of the proposed levels of the disorder by presentation and cause, Akiskal’s model complicates the diagnostic process and makes it difficult to offer novel or interesting insights on the disorder.


In the paper “Modeling mood disorders: An ACE solution?” Gin S. Mahli, M.D. and colleagues propose the ACE Model and argue for a focus on recurrence, lifetime course, and mixed states. The ACE Model comprises a three-dimensional scale with axes of activity, cognition, and emotion. Among other states, the scale includes pure mania and pure depression, the extremes of all three axes. Like a two-axis graph has quadrants, this one has octants (refer to the photo included at the bottom of this article). The remaining six octants are home to mixed states, such as agitated depression (low mood and cognition, and high activity) and unproductive mania (high mood and activity, and low cognition). ​​Significantly, this model invalidates the “with mixed features” specifier in the DSM-V. Also of note, psychosis is measured independently because of its suggested association with schizophrenia.

While Malhi’s model conflicts with other researchers’, I believe his model is meritful, as it captures nuances that other models leave out. Namely, it attends to less severe episodes and explains how symptoms can converge in a single patient to result in widely varying episodes across time. Similarly, the model explains differences between bipolar patients and their episodes.

Usefulness of a Bipolar Spectrum

The models discussed above point to a scope and complexity beyond those presented in the DSM-V categories, demonstrating the potential existence of a more nuanced bipolar spectrum, beyond the currently accepted labels of Bipolar I, Bipolar II, Cyclothymic disorder, and Bipolar Not Otherwise Specified (NOS). I’ll now discuss a spectral approach which considers a range from Depressive Disorder with Mixed Features and Cyclothymia, at the low end, to Bipolar I, at the highest. These disorders or states would no longer be viewed as separate, and severity would be the only distinguishing factor. While this approach might not fully capture the disorder, it is a step in the right direction.

Although the transition to a spectral classification of bipolar would be a significant shift, it is beneficial in many ways. First, it would challenge the limiting criteria in the DSM-V and be more inclusive, rendering it easier to diagnose people with Bipolar II and Bipolar NOS. These people are often overlooked because mental health professionals focus most on Bipolar I. This is unfortunate because misdiagnoses and missing diagnoses can lead to the worsening of symptoms. In better capturing differing presentations, a spectral approach would benefit not only wrongly diagnosed patients but also patients who have already been diagnosed. In “The existential crisis of bipolar II disorder,” the authors use the analogy of an auto-immune disorder to demonstrate that bipolar disorder presents with different levels of severity, stating that there can be “milder or a more severe flareup” (Gitlin & Malhi, 2020).

Figure 5 of “Modeling mood disorders: An ACE solution?”


Akiskal, H. S., & Pinto, O. (1999). The evolving bipolar spectrum. Prototypes I, II, III, and IV. The

Psychiatric clinics of North America, 22(3), 517–vII .

Angst J. (2013). Bipolar disorders in DSM-5: strengths, problems and perspectives. International

journal of bipolar disorders, 1, 12.

Bauer, M., Glenn, T., Rasgon, N., Marsh, W., Sagduyu, K., Grof, P., Alda, M., Murray, G.,

Munoz, R., Quiroz, D., Bauer, R., Jabs, B., & Whybrow, P. C. (2011). Decreasing the minimum length criterion for an episode of hypomania: evaluation using self-reported data from patients with bipolar disorder. European archives of psychiatry and clinical neuroscience, 261(5), 341–347.

Gitlin, & Malhi, G. S. (2020). The existential crisis of bipolar II disorder. International Journal of

Bipolar Disorders, 8(1), 5–5.

Mason, B. L., Brown, E. S., & Croarkin, P. E. (2016). Historical Underpinnings of Bipolar

Disorder Diagnostic Criteria. Behavioral sciences (Basel, Switzerland), 6(3), 14.

Malhi, Irwin, L., Hamilton, A., Morris, G., Boyce, P., Mulder, R., & Porter, R. J. (2018). Modelling

mood disorders: An ACE solution? Bipolar Disorders, 20(S2), 4–16.

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