Bipolar disorder (BD) is a serious mental health condition defined by significant shifts in mood, energy, activity, and thought patterns. It is characterized by alternating episodes of elevated or irritable mood (mania or hypomania) and periods of profound depression. While BD affects an estimated 0.5% to 1.6% of the global population, the question of whether its diagnosis is increasing beyond its true prevalence remains a central debate in modern psychiatry. This discussion centers on the complexity of symptom presentation and external factors that may lead to the incorrect application of the diagnosis, often referred to as overdiagnosis.
The Core Diagnostic Challenge
The inherent difficulty in diagnosing bipolar disorder accurately stems from its clinical presentation. Most individuals with BD, particularly those with Bipolar II, seek treatment during a depressive episode, not a manic or hypomanic one. Since the diagnostic criteria for a major depressive episode are identical for both unipolar depression and bipolar depression, differentiation is challenging for clinicians.
The full course of bipolar disorder is dominated by depressive symptoms. This pattern often leads to an initial misdiagnosis of Major Depressive Disorder (MDD), which can delay a correct diagnosis by an average of five to ten years. The mild nature of hypomania in Bipolar II disorder is particularly difficult to identify, as patients may not recognize it as an illness state or may not report it during a depressive episode.
Complicating the diagnosis further is the existence of mixed features, where an individual experiences both depressive and manic or hypomanic symptoms simultaneously. The presence of subthreshold symptoms, which do not meet the full criteria for a mood episode but still impact functioning, also adds complexity to accurately identifying the disorder.
Conditions Frequently Mistaken for Bipolar Disorder
The symptomatic overlap between bipolar disorder and other psychiatric conditions is a major reason for diagnostic confusion and potential overdiagnosis. Major Depressive Disorder (MDD) is the most common misdiagnosis for individuals who actually have bipolar disorder, especially Bipolar II, because the depressive phases are virtually indistinguishable based on presentation alone. Clinicians must rely heavily on a detailed history of past mood elevations to distinguish MDD from BD.
Borderline Personality Disorder (BPD) is frequently confused with BD due to shared features like mood instability, impulsivity, and intense emotional shifts. A key differentiator is the duration of mood changes; mood swings in BPD are often abrupt, situational, and last a few hours, whereas bipolar mood episodes are distinct, sustained periods lasting days or weeks.
Attention-Deficit/Hyperactivity Disorder (ADHD) shares symptoms of impulsivity, hyperactivity, and distractibility with hypomania. However, ADHD is characterized by a persistent disturbance in attention and activity that begins in childhood and follows a chronic course. In contrast, bipolar symptoms are episodic, representing a change from a person’s typical baseline, though the disorders often co-occur.
Factors Contributing to Increased Diagnosis Rates
The perception that bipolar disorder is being overdiagnosed is fueled by several systemic factors. Changes in the diagnostic criteria have broadened the definition of the disorder over time, increasing the number of people who meet the threshold for a diagnosis. For example, the recognition of Bipolar II disorder, which includes less severe hypomanic episodes, significantly expanded the bipolar spectrum.
The introduction of categories like “Other Specified Bipolar and Related Disorders” allows for a diagnosis in cases with insufficient duration or symptom severity, further extending the spectrum. While the fifth edition of the diagnostic manual attempted to counteract this trend by requiring “increased energy or activity” for a diagnosis of mania or hypomania, the overall effect of these changes has been a widening of the diagnostic net.
Another contributing factor is the influence of pharmaceutical marketing, which has promoted the idea that bipolar disorder is widely underdiagnosed. This marketing encourages a lower threshold for diagnosis, particularly for conditions that respond to profitable mood stabilizers and antipsychotic medications. Clinical settings with limited time for comprehensive assessment also contribute to misdiagnosis, as brief screenings may lead to a quick, incorrect label instead of a thorough clinical interview.
Implications of Diagnostic Error
The consequences of an incorrect diagnosis of bipolar disorder can be substantial. When a person with underlying bipolar disorder is mistakenly diagnosed with Major Depressive Disorder, they are often treated with antidepressant monotherapy. This practice risks triggering a manic episode or accelerating mood cycling, which can worsen the illness course and lead to rapid cycling.
Conversely, an overdiagnosis of BD can result in patients being prescribed mood stabilizers and antipsychotics unnecessarily. These medications carry a risk of side effects, including metabolic changes and weight gain, without the benefit of treating the actual underlying condition. The misdiagnosis also delays the initiation of effective treatment for the patient’s true disorder, whether it is BPD, MDD, or ADHD.
Receiving a serious, chronic diagnosis like bipolar disorder carries significant psychological and social weight, including potential stigma and altered self-perception. When the diagnosis is incorrect, the individual faces unnecessary emotional burden and may experience increased healthcare costs and a prolonged course of instability. Diagnostic accuracy is paramount to ensure patients receive the appropriate pharmacological and psychosocial interventions needed to achieve stability.