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Editor's Note:
Surveys indicate that up to 70% of patients with bipolar disorder are incorrectly diagnosed with unipolar or major depression. Because traditional antidepressant therapy can destabilize this population, misdiagnosis thus has significant consequences. To reduce the incidence of misdiagnosis, Robert Hirschfeld, MD, and his colleagues developed the Mood Disorder Questionnaire (MDQ), a brief survey to detect past episodes of mania in patients with depression. On behalf of Medscape, Jessica Gould interviewed Dr. Hirschfeld about this instrument. Dr. Hirschfeld is the Titus Harris Chair of the Department of Psychiatry and Behavioral Sciences at the University of Texas Medical Branch in Galveston.

Medscape: What prompted you to develop the questionnaire for bipolar disorder?

Dr. Hirschfeld: A bipolar screening tool was actually prompted by a man named Sean Nolan, who worked for Avis Pharmaceuticals; he suggested that we needed a screening instrument for bipolar disorder. At the time, I thought it was foolish and that it was obvious that we didn't need it. How wrong I was!

Medscape: Why did you think it was foolish, and what led you to change your mind?

Dr. Hirschfeld: At the time we were conceptualizing the Mood Disorder Questionnaire (MDQ), I believed that mental health professionals rarely missed the diagnosis of bipolar disorder. Research findings, including those from my own studies, proved that opinion wrong.

Medscape: How did you formulate the questionnaire?

Dr. Hirschfeld: I put together a small work group. We came up with a set of questions drawn from the DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition), from our clinical experience, and from research interviews that were created to diagnose bipolar disorder. Then we compiled them and tested them in our clinics in a group of patients who had bipolar and other psychiatric disorders. We used various psychometric techniques to devise the 13 yes/no questions that are now widely in use. Since that time, we've carried out a number of validations in other populations.

We conducted the original validation in several psychiatric clinics that tended to specialize in mood disorders. We subsequently tested it in a large nationwide community survey. This was a group, not of patients, but of citizens who were part of an ongoing epidemiologic survey.

We've also tested the MDQ in several primary care clinics, and it has been translated into a number of languages throughout the world. So it's very widely used.

Medscape: When and how should providers use the questionnaire?

Dr. Hirschfeld: My recommendation is to give it to anyone who is going to be prescribed an antidepressant, especially to treat depression. Approximately 1 in 4 or 5 people who present with depression are going to have bipolar disorder in some form. You're going to find quite a few people with bipolar simply by administering the questionnaire. Then, if you get a positive screen, you'll want to evaluate the individual more carefully for bipolar disorder. Because simply getting a positive screen does not mean that you've got bipolar disorder.

Medscape: I can conceive of situations in which people without bipolar disorder might answer "yes" to several of your questions -- sleeping patterns disrupted while cramming for an exam, the stress of a new job, or perhaps the elation of falling in love. How do you distinguish these cases from someone presenting with the symptoms of bipolar disorder?

Dr. Hirschfeld: It is true that many of the symptoms of mania are emotions people can experience for a variety of reasons other than having a psychiatric disorder. That's why it's important to conduct the clinical interview. In the clinical interview, we're going to try to see whether these things co-occurred, whether they lasted for a significant period of time, and perhaps of greatest importance, whether they caused a problem.

Medscape: What constitutes a problem?

Dr. Hirschfeld: It could be a problem in a relationship, a problem in a job, a legal problem. Did they create some kind of a mess or cause dysfunction in any way? These are fundamental to the diagnosis of all psychiatric disorders, but it's particularly an issue with bipolar disorder, because people who do have the disease make very bad decisions. Their judgment is impaired, and when they are at the far end of the spectrum, they can actually be delusional.

Medscape: I know that bipolar disorder is often accompanied by a high degree of denial. I would imagine it could be difficult to get such patients to fill out the questionnaire.

Dr. Hirschfeld: It's not necessarily difficult to get them to fill out the questionnaire, but they may not regard things that happen to them to be a problem, especially if they are high at the time. An unfortunate lack of insight is really fundamental to the illness and just compounds the problems.

Medscape: How do you get around the problem of lack of insight?

Dr. Hirschfeld: The lack of insight presents a sometimes insurmountable barrier to initiating treatments and certainly to ongoing adherence to treatment. Often it is only after several episodes with devastating consequences that individuals begin to confront, in a realistic way, the fact of their illness and what they need to do to help improve their lives.

The MDQ has certainly been used by many family members to help demonstrate to individuals that they might have bipolar disorder. People may be able to see themselves in some of the answers to some of the questions raised.

Medscape: Can you envision similar questionnaires for other disorders?

Dr. Hirschfeld: Certainly the use of questionnaires, especially if they are brief and simple, can help identify problems that are frequent and that are frequently being missed.

Medscape: What kind of feedback have you received about the questionnaire within the psychiatric community of providers?

Dr. Hirschfeld: Most respond positively. There were some questions about sensitivity and specificity and so on. It is not a perfect instrument, to be sure. One of the problems with bipolar disorder is that people can answer one way today and then another way at another time.

Medscape: What are you working on now?

Dr. Hirschfeld: Well, we just completed a study that involved giving the MDQ to everyone who was arrested in Galveston County. It's part of a screen that the police do. Everyone who gets arrested gets a medical screen. One of the things that police are interested in is identifying people who might be at risk for suicide and who have very significant medical problems.

The rates of bipolar disorder were somewhat lower than we expected. I expected it to be in the range of 10% to 20%, and I think that a possible reason it was below that range is, not because there is a low incidence of bipolar disorder among people being arrested, but rather because you get a huge amount of naysaying.

We are also looking at what happens to responses over time, at the stability of the instrument. We're giving it to people at several time frames and then comparing their answers.

We just completed a version to compare the prevalence of bipolar disorder in Britain vs the United States. We came up with a slightly lower prevalence in Britain -- under 3%. Our 2 nationwide community studies using the MDQ also suggest that the prevalence of bipolar disorder in Britain may be lower than that in the United States. This may not, in fact, be true, but may reflect differences in how people in England respond to questionnaires about manic behaviors compared with how people in the United States respond. We are hoping to replicate these studies in many other countries to help elucidate this. We are working specifically on programs in France, Spain, and Canada. Furthermore, we're looking at the prevalence of bipolar disorder in adolescents. To my knowledge, this is the first look at the prevalence of bipolar in adolescents in a community study.

This interview is published in collaboration with NARSAD, The Mental Health Research Association, and is supported by an educational grant from GlaxoSmithKline.