What is the Difference Between Bipolar 1 and Bipolar 2?
Bipolar 1 vs. Bipolar 2
Navigating the complexities of bipolar disorder involves distinguishing between its two primary types: Bipolar 1 and Bipolar 2. This often causes confusion, even among mental health providers! A common misconception is that Bipolar 2 is a less severe version of Bipolar 1. While hypomanic episodes in Bipolar 2 are less severe than manic episodes in Bipolar 1, this does not mean that Bipolar 2 is less serious. Both conditions are distinct and can be equally challenging, especially due to the depressive episodes in Bipolar 2.
In this article, we’ll provide an overview of bipolar disorders and then dive into their distinguishing features.
Contents:
Types of Bipolar Disorders
Bipolar disorders as described in the DSM-5 cause extreme fluctuations in mood, energy, and ability to function. The term "bipolar" reflects the experience of shifting between two emotional poles—highs and lows—with little warning.
What are the Differences Among Bipolar 1, Bipolar 2 and Cyclothymia?
Bipolar disorders are primarily categorized into three main types:
Bipolar 1
Characteristics: Full manic episodes marked by euphoric highs, boundless energy, impulsive behaviors, and possibly depressive episodes.
Diagnosis: Requires at least one manic episode, with or without depressive episodes.
Bipolar 2
Characteristics: Longer-lasting depressive episodes and hypomania, but without full manic episodes.
Diagnosis: Requires at least one hypomanic episode and one major depressive episode.
Cyclothymic Disorder
Characteristics: Fluctuates between milder depression and hypomania, lasting at least two years but not reaching criteria of full mania or depression (NIMH).
The Episodic Nature of Bipolar Disorders
Bipolar disorder is episodic, meaning individuals experience periods of symptoms interspersed with phases of stability (referred to as euthymia). Mood cycles can vary greatly, with some persons experiencing rapid cycling and others, more prolonged phases. Mixed episodes, featuring characteristics of both mania and depression, can also occur.
Prevalence and Impact
Current figures suggest that about 2.4% of people worldwide experience bipolar spectrum disorders (Merikangas et al., 2011, Rowland et al., 2018 ). In the U.S. approximately 2.8% of adults experience bipolar disorder, and around 4.4% will encounter it at some point in their lives (NIMH).
Bipolar disorder can significantly influence both mental and physical health, reducing life expectancy by 9 to 13 years compared to the general population. On average, it takes 10 years from the onset of symptoms to acquire a diagnosis (Shen, 2018).
Age of Onset
Symptoms of bipolar disorder typically first emerge during adolescence or early adulthood, but there is often a significant delay between the initial appearance of symptoms and a formal diagnosis. The teenage years, which are marked by significant emotional and hormonal changes, complicate the diagnosis of bipolar disorder. It can be challenging to distinguish between the normal range of adolescent behaviors and the more pronounced mood fluctuations characteristic of bipolar disorder.
While there has been an increase in the recognition of bipolar disorder in younger individuals, this trend is not without controversy. The main challenge lies in differentiating between typical adolescent behavior and the symptoms of bipolar disorder. This complexity often contributes to the delay in diagnosis and appropriate treatment.
How are Bipolar 1 and 2 Different?
The primary difference between Bipolar 1 and Bipolar 2 is the presence and characteristics of manic or hypomanic episodes.
Manic Episode (Bipolar 1)
Duration: At least seven days or requires hospitalization.
Symptoms: Intense elevated mood, heightened energy, reduced need for sleep, possible loss of reality-based perceptions, high-risk behaviors.
Severity: Often disabling, possibly including psychotic symptoms (psychotic symptoms are present 50% of the time).
Hypomanic Episode (Bipolar 2)
Duration: At least four days.
Symptoms: Elevated mood and increased activity not severe enough to cause significant disruption or require hospitalization.
Severity: Less disabling than manic episodes.
Diagnostic Criteria
Bipolar 1: Characterized by at least one manic episode, which may be followed by hypomanic or depressive episodes (the presence of a depressive episode is not required for a diagnosis).
Bipolar 2: Defined by at least one hypomanic episode and one major depressive episode, without any full manic episodes.
Episode Duration and Severity
At first glance, it might seem that the primary difference between Bipolar 1 and Bipolar 2 lies solely in the presence of manic episodes. While this is indeed a defining distinction, there are other important differences in how these conditions manifest and progress.
Bipolar 2 is characterized by a dominance of depressive episodes. The ratio of depressive to hypomanic episodes in Bipolar 2 is significantly higher compared to Bipolar 1. In Bipolar 1, the ratio of major depressive episodes to manic/hypomanic episodes is about 3:1. In stark contrast, Bipolar 2 presents a 39:1 ratio of major depressive episodes to hypomanic episodes. This substantial difference underscores the predominance of depression in Bipolar 2, highlighting its significant impact on the lives of people with Bipolar 2 (Judd et al., 2002; Judd et al., 2003).
As individuals with Bipolar 2 age, they tend to experience fewer hypomanic episodes and more depressive episodes. This pattern often leads to Bipolar 2 being misdiagnosed as unipolar depression, even though bipolar depression can have distinctly different characteristics. Some atypical features of bipolar depression include:
Early Onset: Episodes of depression typically begin before the age of 25.
Physical Sensations: Individuals may experience a feeling of heaviness in their limbs, often described clinically as leaden paralysis.
Increased Appetite and Weight Gain: Unlike typical depression, bipolar depression often involves an insatiable appetite and significant weight gain.
Impact on Daily Life
A common myth is that Bipolar 1 is more severe due to its manic episodes. However, while these episodes can be more disruptive, the prolonged depressive episodes in Bipolar 2 can also be profoundly disabling and their effects often underestimated. It is inaccurate to say one form is more "severe" than the other; they are two different conditions that impact people differently.
Treatment Considerations
Both types of bipolar disorder require comprehensive treatment plans tailored to the person’s unique symptoms and life context. Treatment may include medication, psychotherapy, lifestyle adjustments, and supportive strategies. Recognizing the specific type of bipolar disorder is crucial for guiding appropriate and effective care. Additionally, treatment plans should consider any conditions or forms of neurodivergence such as ADHD, autism, OCD, or eating disorders, which co-occur with bipolar at higher rates than in the general population and which can further influence the expression of the bipolar disorders.
Conclusion
While Bipolar I and Bipolar 2 share many overlapping features, they are distinct conditions with different progressions. In the simplest terms, the difference between Bipolar I and Bipolar 2 comes down to whether or not the person has experienced a manic episode. When you dive deeper, however, you'll find that the differences don't stop there. Those with Bipolar 2 tend to experience more depressive episodes, which can be quite long and severe. Understanding these distinctions is important for anyone dealing with these complex mood disorders, ensuring that treatment is appropriately aligned with the person’s specific needs.
For those looking to deepen their understanding; further reading and resources are available to explore the nuances of each type of bipolar disorder.
For a deep dive into the diagnostic criteria for Bipolar I, see the DSM in Picture series.
For a detailed look at Bipolar 2 criteria, explore the DSM in Picture series.
Discover the overlap between ADHD and Bipolar in this informative infographic.
Learn about the overlap of autism and bipolar disorder in this infographic.
Understand the overlapping traits with ADHD vs. Bipolar in the Misdiagnosis Monday post.
Explore the diagnostic confusion between autism and bipolar in the Misdiagnosis Monday post.
References
American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.).
Judd, L. L., Akiskal, H. S., Schettler, P. J., Endicott, J., Maser, J., Solomon, D. A., et al. (2002). The long-term natural history of the weekly symptomatic status of bipolar I disorder. Archives of General Psychiatry, 59, 530-537.
Judd, L. L., Akiskal, H. S., Schettler, P. J., Coryell, W., Endicott, J., Maser, J. D., et al. (2003). A prospective investigation of the natural history of the long-term weekly symptomatic status of bipolar II disorder. Archives of General Psychiatry, 60, 261-269.
Merikangas, K. R., Akiskal, H. S., Angst, J., Greenberg, P. E., Hirschfeld, R. M. A., Petukhova, M., & Kessler, R. C. (2007). Lifetime and 12-month prevalence of bipolar spectrum disorder in the national comorbidity survey replication. Archives of General Psychiatry, 64(5), 543. https://doi.org/10.1001/archpsyc.64.5.543
Rowland, T. A., & Marwaha, S. (2018). Epidemiology and risk factors for bipolar disorder. Therapeutic Advances in Psychopharmacology, 8(9), 251–269.
Shen Y. C. (2018). Treatment of acute bipolar depression. Ci ji yi xue za zhi = Tzu-chi medical journal, 30(3), 141–147. https://doi.org/10.4103/tcmj.tcmj_71_18