Caution Urged for Antidepressant Use in
Bipolar Depression

Liam Davenport

July 13, 2020

Although patients with bipolar disorder commonly experience depressive symptoms, clinicians should be very cautious about treating them with antidepressants, especially as monotherapy, experts asserted in a recent debate on the topic as part of the European Psychiatric Association (EPA) 2020 Congress.  

At the Congress, which was virtual this year because of the COVID-19 pandemic, psychiatric experts said that clinicians should also screen patients for mixed symptoms that are better treated with mood stabilizers. These same experts also raised concerns over long-term antidepressant use, recommending continued use only in patients who relapse after stopping antidepressants.

Isabella Pacchiarotti, MD, PhD, Centro de Investigación Biomédica en Red de Salud Mental, Barcelona, Spain, argued against the use of antidepressants in treating bipolar disorder; Guy Goodwin, PhD, however, took the "pro" stance.

Goodwin, a professor of psychiatry at the University of Oxford in the UK, admitted that there is a "paucity of data" on the role of antidepressants in bipolar disorder.

Nevertheless, there are "circumstances that one really has to treat with antidepressants simply because other things have been tried and have not worked," he told conference attendees.

Challenging, Controversial Topic

The debate was chaired by Eduard Vieta, MD, PhD, chair of the Department of Psychiatry and Psychology at the University of Barcelona Hospital Clinic, Spain.

Vieta said the question over whether antidepressants should be used in the depressive phase of bipolar illness is "perhaps the most challenging...especially in the area of bipolar disorder."

At the beginning of the presentation, Vieta asked the audience for their opinion in order to have a "baseline" for the debate: among 164 respondents, 73% were in favor of using antidepressants in bipolar depression.

"Clearly there is a majority, so Isabella [Dr Pacchiarotti] is going to have a hard time improving these numbers," Vieta noted.

Up first, Pacchiarotti began by noting that this topic remains "an area of big controversy." However, the real question "should not be the pros and cons of antidepressants but more when and how to use them."

Of the three phases of bipolar disorder, acute depression "poses the greatest difficulties," she added.

This is because of the relative paucity of studies in the area, the often heated debates on the specific role of antidepressants, the discrepancy in conclusions between meta-analyses, and the currently approved therapeutic options being associated with "not very high response rates," Pacchiarotti said.

The diagnostic criteria for unipolar and bipolar depression are "basically the same," she noted. However, it's important to be able to distinguish between the two conditions, as up to one fifth of patients with unipolar depression suffer from undiagnosed bipolar disorder, she explained.

Moreover, several studies have identified key symptoms in bipolar depression, such as hyperphagia and hypersomnia, increased anxiety, and psychotic and psychomotor symptoms.

As previously reported by Medscape Medical News, a task force report was released in 2013 by the International Society for Bipolar Disorder (ISBD) on antidepressant use in bipolar disorders. Pacchiarotti and Goodwin were among the report's authors, which  concluded that available evidence on this issue is methodologically weak.

This is largely because of a lack of placebo-controlled studies in this patient population (bipolar depression, alongside suicidal ideation, is often an exclusion criteria in clinical antidepressant trials).

Many guidelines consequently do not consider antidepressants to be a first-line option as monotherapy in bipolar depression, although some name the drugs as second- or third-line options.

In 2013, the ISBD recommended that antidepressant monotherapy should be "avoided" in bipolar I disorder; and in bipolar I and II depression, the treatment should be accompanied by at least two concomitant core manic symptoms.

"What Has Changed?"

Antidepressants should be used "only if there is a history of a positive response," whereas maintenance therapy should be considered if a patient relapses into a depressive episode after stopping the drugs, the report notes.

Pacchiarotti noted that since the recommendations were published nothing has changed, noting that antidepressant efficacy in bipolar depression "remains unproven."

The issue is not whether antidepressants are effective in bipolar depression but rather are there subpopulations where these medications are helpful or harmful, she added.

The key to understanding the heterogeneity of responses to antidepressants, she said, is the concept of a bipolar spectrum and a dimensional approach to distinguishing between bipolar disorder and unipolar depression.

In addition, the definition of a mixed episode in the DSM-IV-TR differs from that of an episode with mixed characteristics in the DSM-5, which Pacchiarotti said offers a better understanding of the phenomenon while seemingly disposing with the idea of mixed depression.

Based on previous research, there is some suggestion that a depressive state exists between major depressive disorder and bipolar I disorder with mixed features, and hypomania state between bipolar II and I disorder, also with mixed features.

Pacchiarotti said the role of antidepressants in the treatment of bipolar depression remains "controversial" and there is a need for both short- and long-term studies of their use in both bipolar I and bipolar II disorder with real-world inclusion criteria.

The concept of a bipolar spectrum needs to be considered a more "dimensional approach" to depression, with mixed features seen as a "transversal" contraindication for antidepressant use, she concluded.

In Favor — With Caveats

Taking the opposite position and arguing in favor of antidepressant use, albeit cautiously, Goodwin said previous work has shown that stable patients with bipolar disorder experience depression of variable severity about 50% of the time.

The truth is that patients do not have a depressive episode for extended periods but instead have depressive symptoms, he said. "So how we manage and treat depression really matters."

In an analysis, Goodwin and his colleagues estimated that the cost of bipolar disorder is approximately £12,600 ($16,000) per patient per year, of which only 30.6% is attributable to healthcare costs and 68.1% to indirect costs. This means the impact on the patient is also felt by society.

He agreed with Pacchiarotti's assertion of a bipolar spectrum and the need for a dimensional approach.

"All the patients along the spectrum have the symptoms of depression and they differ in the extent to which they show symptoms of mania, which will include irritability," he added.

Goodwin argued that there is no evidence to suggest that the depression experienced at one end of the scale is any different from that at the other. However, safety issues around antidepressant use "really relate to the additional symptoms you see with increasing evidence of bipolarity."

In addition, the whole discussion is confounded by comorbidity, "with symptoms that sometimes coalesce into our concept of borderline personality disorder" or attention deficit hyperactivity disorder, he said.

Goodwin said there is "very little doubt" that antidepressants have an effect vs placebo. "The argument is over whether the effect is large and whether we should regard it as clinically significant."

He noted that previous studies have shown a range of effect sizes with antidepressants, but the "massive" confidence intervals mean that "one is free to believe pretty much what one likes."

The only antidepressant medication that is statistically significantly different from placebo is fluoxetine combined with olanzapine. However, that conclusion is based on "little data," said Goodwin.

In terms of long-term management, there is "extremely little" randomized data for maintenance treatment with antidepressants in bipolar disorder. "So this does not support" long-term use, he added.

Still, although choice of antidepressant remains a guess, there is "just about support" for using them, Goodwin noted.

He urged clinicians not to dismiss antidepressant use, but to use them only where there is a clinical need and for as little time as possible. Patients with bipolar disorder should continue to take antidepressants if they relapse after they come off these medications.

However, all of that sits "in contrast" to how they're currently used in clinical practice, Goodwin said.

Caution Urged

After the debate, the audience was asked to vote again. This time, among 182 participants, those who voted in favor of using antidepressants in bipolar depression increased to 88%. The remaining 12% voted against the practice.

Summarizing the discussion, Vieta said that "we should be cautious" when using antidepressants in bipolar depression. However, "we should be able to use them when necessary," he added.

Although their use as monotherapy is not best practice, especially in bipolar I disorder, there may be a subset of bipolar II patients in whom monotherapy "might still be acceptable; but I don't think it's a good idea," Vieta said.

He added that clinicians should very carefully screen for mixed symptoms, which call for the prescription of other drugs, such as olanzapine and fluoxetine.

"The other important message is that we have to be even more cautious in the long term with the use of antidepressants, and we should be able to use them when there is a comorbidity" that calls for their use, Vieta concluded.

Pacchiarotti reported having received speaker fees and educational grants from Adamed, AstraZeneca, Janssen-Cilag, and Lundbeck. Goodwin reported having received honoraria from Angellini, Medscape, Pfizer, Servier, Shire, and Sun; having shares in P1vital Products; past employment as medical director of P1vital Products; and advisory board membership for Compass Pathways, Minerva, MSD, Novartis, Lundbeck, Sage, Servier, and Shire. Vieta has disclosed no relevant financial relationships.

European Psychiatric Association (EPA) 2020 Congress. Abstracts D001 and D002. Presented July 6, 2020.

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