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Is underdiagnosis the main pitfall when diagnosing bipolar disorder? Yes

BMJ 2010; 340 doi: (Published 22 February 2010) Cite this as: BMJ 2010;340:c854

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Bipolar depression-under diagnosed and misdiagnosed

There is a traditional misunderstanding that bipolar disorder (BD)
has an abrupt onset of mania followed by depression and such confusion has
its roots in the previous terminology of “manic depression.” Longitudinal
research and clinical studies prove otherwise: an early onset of chronic
mild depression commonly heralds BD. Diagnostic confusion between BD and
schizophrenia may occur in the early stages. A recent study revealed
that 37 per cent of bipolar patients had been initially misdiagnosed as
having unipolar depression 1. Only 9 percent of bipolar type ii patients
were accurately diagnosed2.Patients with bipolar disorder are depressed
three times as often as they are maniacal. If bipolar depression with
undeclared mania is also included under the general category of BD,
bipolar disorder is not only under diagnosed but commonly misdiagnosed.

Atypical depressive features are more noticeable in bipolar
depressives, as is psychomotor retardation 3. Patients also have a
previous history of psychotic depression. Bipolar depression is associated
with more mood lability and a relatively acute onset. When a young person
presents with psychotic depression or psychomotor retardation, bipolar
depression should be ruled out. Non-specific psychological symptoms and
behavioural disturbances may be the precursor of bipolar disorder in young
people. 4 Any patient presenting with depressive symptomatology should be
interrogated about their past history of mood elevation, and the family
history of affective disorders should be explored also. Bipolar depression
can occur with or without precipitating factors. Bipolar depression should
be especially ruled out when depressions occur without an identifiable
psychogenic stressor. A subset of patients diagnosed with unipolar
depression in fact suffers from bipolar depression. 5 When patients fail
to respond to even one antidepressant, bipolarity should be screened if
non adherence and suboptimal dosing are not the reasons for the
antidepressant failure. Non response to antidepressant medication, co-
morbid anxiety, feelings of people being unfriendly, recent depression
diagnosis, bipolar disorder in family history and legal problems may prove
useful indicators of bipolarity.

Agitated depression can simulate hypomania in the sense that there
can be
over activity and pressure of speech, but the over activity is goal
directed and
pressure of speech does not demonstrate logorrhoea. In agitated
depression, patient
complain of a disturbance in their train of thought- racing of thoughts.
This symptom
is different from the flight of ideas noticed in manic state; that is
expressed verbally, with an abundance of words, or in pressured or
obviously logorrhoeic speech. When depressed patients report racing of
thoughts, their speech is at a normal or reduced tempo. The depressed
patient will complain about their pattern of thought as a symptom of
disorder, whereas an elated manic patient never complains about their
flight of ideas. The goal directed over activity of agitated depression
must be differentiated from the unmotivated and destructive hyperactivity
of hypomania. A manic or hypomanic patient enjoys the decreased need for
sleep whereas an agitated depressed patient would be begging for sleep.
It should be remembered that most patients with bipolar disorder seek
treatment for depression, and not for mania or hypomania. In bipolar
depression the typical cognitive distortions of unipolar depression are
absent. They have the feeling of an affective vacuum or blank mood. 6
Bipolar depression is more uninhibited than unipolar depression and
behavioural symptoms predominate than cognitive symptoms.

Bipolar disorder may be essentially a depressive disorder with manic
and depressive expressions and a true biological depression unlike
unipolar depression where the biological changes are biological correlates
rather than etiological factors. Bipolar depression that has not declared
mania or hypomania is under diagnosed and misdiagnosed as unipolar
depression. What is probably needed is a new terminology that would
encompass bipolar depression with undeclared mania or hypomania in the
general category of BD. It is extremely important to diagnose bipolarity
in depression as it carries a higher suicidal risk.

1.Ghaemi SM,Boiman EE,Goodwin FK.Diagnosing bipolar
disorder and effect of antidepressants: a naturalistic study.L.Clinical
Psychiatry 2000; 61: 804-8.

2.Vieta E. Diagnosing and classification of psychiatric disorders In:
N Sussman,ed. Psychiatry. pp 3-8.Round table series 64.London:Royal
Society of Medicine Press, 1994.

3.Mitchell PB,Wilhelm K, Parker G, Austin MP, Rutgers P, Malhi
GS,(2001)The Clinical features of bipolar depression: a comparison with
matched major depressive disorder patients. J Clinical Psychiatry 62:212-

4.Goodwin G.M (2003) Evidence-based guidelines for treating bipolar
disorder: recommendations from the British Association for
Psychopharmacology. Journal of Psychopharmacology 17:2149-173.

5.Hirschfeld RM, Calabrese JR, Weissman MM(2003) Screening for
bipolar disorder in the community. J.Clin Psychiatry 64: 53-59.

6.Colom F,Vieta E. Psycho-education Manuel for Bipolar Disorder.
Cambridge: Cambridge University Press, 2006.

Competing interests:
None declared

Competing interests: No competing interests

28 March 2010
James Paul Pandarakalam
Locum Consultant Psychiatrist
5 Boroughs Partnership NHS Foundation Trust,Leigh Infirmary, Leigh WN7 1HS