Bipolar disorder, historically called manic depression, is a mood disorder defined by extreme shifts in mood, energy, and activity levels. These mood swings cycle between periods of emotional highs and lows. The emotional lows experienced in bipolar disorder are major depressive episodes, which meet the full clinical criteria for depression. The presence of these depressive episodes alongside periods of elevated mood is the central characteristic that defines the condition.
The Depressive Component of Bipolar Disorder
The depressive phases of bipolar disorder are clinically similar to episodes of Major Depressive Disorder (MDD) in their core symptoms. Individuals experience intense sadness, a loss of interest or pleasure, and feelings of hopelessness. These episodes also involve physical symptoms like changes in appetite and weight, altered sleep patterns, and persistent fatigue.
For most people with bipolar disorder, the depressive episodes are the most frequent and enduring aspect of the illness. In Bipolar II disorder, a diagnosis requires at least one major depressive episode along with at least one period of elevated mood. While Bipolar I disorder requires at least one manic episode, depression often precedes or follows this high, and depressive episodes tend to dominate the overall course of the illness.
The depressive symptoms experienced within the context of bipolar disorder are often indistinguishable from MDD, making diagnosis challenging. However, bipolar depression may feature certain signs more often, such as excessive sleeping, greater motor slowing, and the presence of mood instability within the episode itself. Because the depressive phase is so distressing, patients are far more likely to seek treatment when they are experiencing a low mood.
Identifying the Defining Feature: Mania and Hypomania
What separates bipolar disorder from a diagnosis of Major Depressive Disorder is the occurrence of an elevated mood state, known as mania or hypomania. These episodes represent the “up” pole of the mood spectrum and are characterized by abnormally and persistently increased energy and activity. The presence of these high mood states is the determining factor in diagnosing bipolar disorder.
Mania is the defining feature of Bipolar I disorder, representing a severe elevation of mood that lasts for at least one week and significantly impairs daily functioning. Symptoms include a reduced need for sleep, rapid, pressured speech, racing thoughts, and an inflated sense of self-esteem. Individuals in a manic episode may also engage in risky, impulsive behaviors like excessive spending or reckless driving.
Hypomania, which defines Bipolar II disorder, is a less severe form of elevated mood that must last for at least four consecutive days. While hypomania involves similar symptoms to mania, such as increased energy and talkativeness, the episode is not severe enough to cause a marked disruption in work or social life. Unlike full mania, hypomania never involves a break from reality, such as psychosis, which can occur during severe manic episodes in Bipolar I.
Why Accurate Diagnosis Is Often Complex
Accurately diagnosing bipolar disorder is often complicated because patients frequently present for help only during a depressive episode. The distressing nature of depression drives people to seek treatment, while hypomanic episodes may be perceived as positive or highly productive. This tendency means clinicians initially see only the symptoms of depression, leading to a common misdiagnosis of Major Depressive Disorder.
Individuals experiencing hypomania or mania often lack insight into the severity of their behavior. They may not recognize or report these elevated moods during a clinical interview, making it challenging to gather a complete history. This difficulty is especially common in Bipolar II disorder, where hypomanic episodes are milder and may be easily overlooked or downplayed.
Diagnosis relies on a comprehensive lifetime history, which can be difficult to obtain if the patient is reluctant to report past manic or hypomanic symptoms. Receiving an incorrect diagnosis can lead to inappropriate treatment, which can worsen the condition. For instance, treating bipolar depression with an antidepressant alone, without a mood stabilizer, carries the risk of triggering a manic episode or accelerating the cycling between moods.
Treatment Paths for Bipolar Depression
The distinction between bipolar depression and Major Depressive Disorder is important because the treatment strategies differ significantly. For Major Depressive Disorder, the first-line pharmacological treatment typically involves an antidepressant medication, such as a Selective Serotonin Reuptake Inhibitor (SSRI). This approach is often insufficient and potentially destabilizing for a person with bipolar disorder.
The primary focus for managing bipolar disorder, even during a depressive episode, is the use of mood stabilizers. Medications like lithium, lamotrigine, and valproate are foundational treatments that help regulate the extreme mood swings. Atypical antipsychotics are also frequently used, as some have proven efficacy for treating the depressive phase of both Bipolar I and Bipolar II disorder.
If an antidepressant is used in bipolar depression, it is generally prescribed cautiously and must be used in combination with a mood stabilizer to mitigate the risk of inducing mania or hypomania. This combined approach prioritizes stabilizing the overall mood while also addressing the depressive symptoms.