The Diagnostic and Treatment Challenges of Bipolar Depression
Bipolar disorder (BD) is a complex, chronic, progressive and ranks among the leading causes of disability worldwide. The underlying feature of BPD is mood instability, with alternation of manic/hypomanic and depressive episodes and, commonly, significant subsyndromal symptoms between distinct mood episodes. Depressive episodes (and residual depressive symptoms in times of remission) are responsible for much of the disability, suicidal behaviors, and exacerbation of comorbid conditions in BD. Although depression is the predominant presentation and the leading cause of morbidity in BD, it is poorly understood, and the treatment options are limited. Inadequate treatment of bipolar depression leads to residual symptoms which may drive relapse. Effective treatment is of great importance, but it depends on accurate diagnosis and appropriate pharmacotherapy. However, barriers to prompt diagnosis and treatment persist.
Research data suggest that BD is not uncommon among patients with a diagnosis of depression. In a primary care clinic, 21% of patients screened positive for BD and among these, 2/3 had not received a diagnosis of BD before. The frequency of BD is believed to be even higher among patients receiving specialty psychiatric care. In a NIMH study which followed clinical course for at least a year, 25% of participants initially diagnosed with MDD experienced a manic/hypomanic episode which led to a revision in diagnosis to BPD. These findings suggest that figures may be underestimating true prevalence of BD in the population. Differentiating between unipolar and bipolar depression is difficult for both primary care and psychiatric providers. There are no substantial differences in the presentation of depressive episodes between individuals with bipolar disorder and those with unipolar depression. Misdiagnosis is common due to lack of thorough screening and comprehensive evaluation and history to rule out BD in patients presenting with depression.
Misdiagnosis is a significant barrier to recovery because response to treatment and clinical course largely depends on the selection of appropriate pharmacotherapy that addresses the mood instability underlying bipolar depression. Antidepressant therapy- in the absence of mood stabilizing medication- has not demonstrated efficacy in bipolar depression. Current treatment guidelines recommend antidepressant use only as an adjunct to mood stabilizing agents. In general, data show that antidepressants are not particularly effective in bipolar depression (either as single or adjunctive therapy) and there are safety concerns for cycle acceleration and induction of mania among some patients. In addition, initiation of ineffective treatments can prolong the time the patient is symptomatic, with impaired function and lower quality of life.
The diagnosis of BD in depressed patients presents unique challenges to healthcare providers. The depressive phase of bipolar disorder presents many similarities with unipolar depression, and the correct diagnosis can only be made after careful screening and history. Although there are several validated instruments to diagnose major depressive episodes, the options available to primary care providers remain limited. The Mood Disorder Questionnaire (MDQ) is a screening questionnaire that can be used in combination with a thorough history, can improve the chances of identifying individuals with BD if used in combination with a through history. Clinicians should be alert to features suggestive of underlying bipolar disorder such as the presence of subthreshold hypomanic symptoms, a history of multiple failed antidepressant trials, symptoms of ADHD, or comorbid substance abuse (particularly when early in onset). Validating information from the patients’ family members can aid in accurate diagnosis.
Depressed patients with BD have significant unmet needs. Residual morbidity and symptoms are quite common, even among treated patients. The treatment of BD often requires complex pharmacotherapeutic regimens. Most effective mood stabilizing medications are associated with challenging adverse events, which limits their tolerability and requires watchful monitoring. In addition to the burden of adverse events, patients with BD can experience loss of response or depressive symptoms that fail to improve after multiple medication trials. Additional medication options are needed. Research for novel pharmacotherapies should focus on developing potential, better-tolerated treatments for Bipolar depression.
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