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Zealously over or under?

26th Oct 2011
Lynnette Hoffman   all articles by this author

Has the effort to correct the problem of underdiagnosis of bipolar disorder shifted too far in the opposite direction?

LAST spring two parents in a seaside village in Massachusetts were convicted of murdering their four-year-old daughter by administering a lethal combination of a high dose of clonidine and an antihistamine.1,2

The little girl, Rebecca Riley, had been diagnosed with bipolar disorder at the age of two, and along with clonidine, she’d also been taking the antipsychotic quetiapine and the mood stabiliser divalproex sodium (not available in Australia).

But as details of the case emerged, it wasn’t just the actions of the girl’s parents that had people concerned.

Earlier this year the psychiatrist who made the diagnosis and prescribed the medications settled a medical malpractice case for $2.5 million, which will go to the girl’s two siblings, who had also been diagnosed with bipolar disorder.3

Court testimony portrayed the psychiatrist as having been duped into a diagnosis of bipolar disorder by cunning parents who wanted to silence their children. After the girl’s death the psychiatrist voluntarily stopped practising, but the licensing board permitted her to resume practice and she is now back at work.

It’s an extreme example of a diagnosis gone wrong, and so far no such cases have cropped up in Australia. But some psychiatrists say that while we haven’t reached those extremes, there is a worrying trend toward doctors being persuaded by patients’ own self-diagnosis of bipolar disorder, or desire for immediate treatment – even if there’s not sufficient evidence to support it. 

Historically, the biggest concern has been underdiagnosis of bipolar disorder. But Professor Gin Malhi, head of psychological medicine at the University of Sydney and editor of the Australian and New Zealand Journal of Psychiatry, says while cases of bipolar disorder do continue to go unrecognised, overdiagnosis is becoming a problem of equal or possibly even greater proportions. 

“I think the threshold for diagnosing bipolar II disorder, in particular, has dropped,” Professor Malhi says.

“The zeal for the underdiagnosis of bipolar disorder has led to overdiagnosis in certain circumstances… It just reflects really that we don’t have a very good mechanism to diagnose, hence we’re losing at both ends.

“People who have clear mania, clearly are bipolar, but there are other kinds of symptoms that can look like mania or overlap with mania.

“The temptation is to define people with depression and very occasional periods of feeling high or elated as having bipolar disorder.” 

Another prominent psychiatrist who shares Professor Malhi’s concerns is University of New South Wales professor of psychiatry Philip Mitchell, who articulated the complexities of balancing early but accurate diagnosis in a paper he co-wrote for the MJA last year.4

Professor Mitchell points to an American study published in 2008 in which 700 psychiatric outpatients at a hospital in Rhode Island were interviewed with the Structured Clinical Interview for DSM-IV (SCID).5

Less than half the patients who had previously been diagnosed with bipolar disorder by a health professional received that diagnosis based on the SCID test.

Data collected about their family history (which those diagnosing were blinded to) showed that patients with SCID-diagnosed bipolar disorder had a significantly higher morbid risk of bipolar disorder than patients who self-reported a previous diagnosis of bipolar disorder not confirmed by the SCID.

In fact, patients who told doctors they had bipolar disorder, which was not diagnosed using SCID, had the same morbid risk for bipolar disorder as those patients without bipolar disorder.

Like Professor Malhi, Professor Mitchell believes that patients are being diagnosed who don’t fulfil the criteria, “even broad criteria”. 

Whereas traditionally the criteria for diagnosing a hypomanic episode consisted of at least 2–4 days of elevated mood, that has been expanded to encompass a few hours or a day of elevated mood, Professor Mitchell says. 

“A number of websites around the world have these checklists based on the Mood Disorder Questionnaire, so patients are incorrectly labelling periods of normal enthusiasm and excitement as hypomania. 

“They’re coming to their doctors saying ‘I have bipolar disorder’, so I think the problem is patients are self-diagnosing and I think medical practitioners need to be much more critical… Clinicians need to use their own skills and judgement,” he says.

Both experts say more context is needed to diagnose bipolar disorder and doctors need to use their clinical judgement and be critical, rather than treating the DSM-IV as an authoritative checklist.

They say that while certain characteristics may indeed raise the risk of bipolar disorder, they should be treated as such – and monitored closely with a longitudinal approach rather than jumping into treatment prematurely.

However, it would be misleading to claim the views of specialists such as Professors Mitchell and Malhi are unanimous in the field.

Professor Gordon Parker, executive director of the Black Dog Institute, has written numerous papers about the dangers and prevalence of unrecognised bipolar disorder, and he is among those who say the broader criteria still produces accurate results. 

“The current duration of mandated highs in the DSM does not accord with clinical observation, and many studies are showing that brief highs of a day or so do not differ by severity or clinical features from highs lasting a week or longer,” Professor Parker says, pointing out that the DSM-5 is set to reduce the criteria for minimum duration as well.

Along with distinctive highs, above and beyond normal happiness, Professor Parker says features such as a ‘bulletproof’ lack of anxiety, as well as the patient’s retrospective awareness of the consequences – such as spending large amounts of money or major sexual indiscretions – and the feelings of guilt and shame that follow, are among the features that differentiate hypomania.

As for the Mood Disorders Questionnaire and Mood Swings Questionnaire screen tests, when used in patients with depression (as opposed to the general community) their accuracy for bipolar disorder is about 80%, Professor Parker says. 

“Bipolar II disorder possesses categorical mood-related features that are distinct from normal happiness and unhappiness. 

“It is associated with the highest suicide rate of all psychiatric conditions – largely reflecting failures to diagnose.”

Professors Malhi and Mitchell don’t dispute the importance of timely and accurate diagnosis of bipolar disorder.

But they say the problems associated with overdiagnosis are not merely academic.“Bipolar disorder is a serious diagnosis with stigma attached, and the side effects of medications can be quite severe – so you want to be sure that only those patients who need them, get them,” Professor Mitchell says.

“Patients [with broadly defined mania symptoms] will be given the same medications as patients are given for clear bipolar disorder. The difficulty with these lower thresholds is there’s no evidence that these patients actually benefit from the mood stabilisers.”

Making a bipolar disorder diagnosis*

For patients experiencing a major depressive episode with no clear prior episodes of hypomania or mania, Professor Mitchell and his colleagues recommend doctors forgo making an immediate diagnosis and instead take a “probabilistic approach” looking at specific features that indicate greater risk of developing bipolar disorder. These include:

- Depressed patients with an ambiguous past history of hypomanic or manic episodes

- ‘Unipolar depressed’ patients with a family history of bipolar disorder

- Young patients presenting with recurrent depressive episodes only (where it is unclear whether this represents a first presentation of bipolar disorder or unipolar depression)

- “At present, we do not recommend that clinicians immediately diagnose and treat depressed patients with these features as definitely having bipolar disorder, but commend practitioners to seriously consider this possibility for such individuals as treatment progresses,” the authors write.

Further, they recommend watching closely for early warning signs of manic or depressive episodes.

Possible warning signs for manic episodes:

- Increased activity and busyness

- Reduced need for sleep

- Impulsive behaviour

- Speaking in a caustic manner

- Telephoning friends indiscriminately.

Possible warning signs for depressive episodes:

- Feeling tearful, moody, withdrawn, snappy, slowed down, negative, stubborn, pessimistic, hopeless or excessively self-doubting

*MJA 2010; 193: S10–S13

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