The relationship between depression and Bipolar Disorder is often confusing. The answer is yes: a person with Bipolar Disorder experiences periods of depression because depression is one of the two primary mood states that define the condition. Bipolar Disorder is characterized by dramatic shifts in mood, energy, and activity levels, fluctuating between episodes of elevated or irritable mood (mania or hypomania) and episodes of major depression. The presence of depressive episodes is often why Bipolar Disorder is mistakenly identified as Major Depressive Disorder, especially when a person first seeks help during a depressive low.
The Depressive Phase of Bipolar Disorder
Depression is an inherent component of Bipolar Disorder, forming one of the two “poles” of the illness. For most individuals with Bipolar I and Bipolar II, the duration spent in a depressed state is often longer than the time spent in an elevated mood state. For example, a diagnosis of Bipolar II Disorder requires at least one episode of major depression and at least one hypomanic episode.
The depressive episodes within Bipolar Disorder, often called bipolar depression, can present with features that differ from unipolar Major Depressive Disorder. These differences are sometimes referred to as “atypical features,” even though they are common in bipolar depression. Atypical features often include sleeping excessively (hypersomnia) and a significant increase in appetite or weight gain. Another common feature is “leaden paralysis,” a heavy, weighted-down feeling in the arms and legs.
A person experiencing bipolar depression may also exhibit “mood reactivity,” meaning their mood can temporarily improve in response to positive events. Bipolar I Disorder is defined by the occurrence of at least one full manic episode; depressive episodes are common but not strictly required for diagnosis. Conversely, Bipolar II Disorder is defined by major depressive episodes alternating with less severe periods of elevated mood (hypomania). The depressive episodes in Bipolar II are often more frequent and long-lasting than those seen in Bipolar I.
Distinguishing Bipolar from Major Depressive Disorder
The difficulty in diagnosis arises because individuals with Bipolar Disorder almost always seek treatment during a depressive episode, making the presentation appear identical to Major Depressive Disorder (MDD). MDD is referred to as unipolar depression because it involves only the low mood state, without any history of elevated mood swings. The key clinical difference defining Bipolar Disorder is the history of mania or hypomania.
Bipolar Disorder requires evidence of past or current elevated mood episodes: a full manic episode for Bipolar I or a hypomanic episode for Bipolar II. Manic episodes are severe, lasting at least seven days or requiring hospitalization, and cause clear impairment in functioning. Hypomanic episodes are less severe and shorter, lasting at least four consecutive days, but still represent a noticeable change in behavior and energy. Since individuals often do not recognize hypomania as a problem, they frequently fail to report it to their doctor.
Clinicians must specifically ask about periods of unusually high energy, reduced need for sleep, rapid speech, and increased goal-directed activity to uncover a history of elevated moods. A diagnosis of MDD is only given if there has been no history of a manic or hypomanic episode. Without careful screening, a person with Bipolar Disorder can be misdiagnosed with unipolar depression for many years.
Understanding Mixed Features
A diagnostic feature unique to Bipolar Disorder is the presence of “mixed features,” which complicates the clinical picture. Mixed features occur when a person experiences symptoms of both poles of the illness simultaneously or in rapid succession. This means a person may be in a major depressive episode but also exhibit three or more symptoms of mania or hypomania.
For example, an individual might feel profoundly hopeless and sad while simultaneously experiencing racing thoughts, agitation, and high energy. This state is particularly dangerous because depressive symptoms, such as despair and suicidal thinking, are paired with the energy and impulsivity of a manic state. The risk of self-harm and suicide is higher during episodes with mixed features compared to a pure depressive episode.
The presence of mixed features serves as a strong indicator that the underlying condition is Bipolar Disorder, not unipolar depression. Mixed episodes are challenging to manage, as the conflicting symptoms create internal turmoil. This unique presentation highlights why a comprehensive assessment is necessary beyond simply identifying depression.
Why the Correct Diagnosis Matters for Treatment
The distinction between Major Depressive Disorder and Bipolar Disorder is not merely academic; it has profound consequences for treatment. Misdiagnosis is common, with nearly 70% of people with Bipolar Disorder initially receiving an incorrect diagnosis, most often MDD. The standard treatment for MDD involves traditional antidepressant medications, such as selective serotonin reuptake inhibitors (SSRIs).
Treating Bipolar Disorder solely with these antidepressants carries a significant risk of destabilizing the patient’s mood. Antidepressants, when used without a mood-stabilizing agent, can inadvertently trigger a manic or hypomanic episode. This may also lead to “rapid cycling,” where mood episodes occur more frequently, making the illness harder to manage.
In contrast, the appropriate treatment for Bipolar Disorder centers on medications designed to stabilize mood, such as mood stabilizers or atypical antipsychotics. These medications smooth out the dramatic high and low swings, reducing the frequency and severity of both manic and depressive episodes. An accurate diagnosis is the necessary first step to ensure a patient receives the proper combination of medication and psychotherapy, preventing unnecessary suffering and increased risk of suicide.