Bipolar disorder is often diagnosed as major
depression
It is retrospectively reported that approximately one-third
of patients with bipolar disorder will have been initially
diagnosed as having major depression; this is because:2
1. Depression is more common
2. Depression is the most frequent symptom experienced
by people with bipolar disorder and during an episode
of mania people are less likely to consider themselves
unwell and therefore will not present for treatment
3. The criteria for a diagnosis of major depression is the
same as the diagnosis of depression in patients with
bipolar disorder
4. Patients may not remember, or may be embarrassed
about, manic episodes and therefore be reluctant to
report them
Treatment for depression with antidepressants can have
serious consequences for patients with bipolar disorder.2 If an
antidepressant is prescribed to a patient with bipolar disorder
it is usually in combination with a mood stabiliser, e.g. lithium,
to reduce the risk of a swing to mania (Page 13).9 Increased
mood cycling has been reported in patients with bipolar
disorder taking antidepressant monotherapy.11 A study of
over 3000 patients with bipolar disorder treated with either
an antidepressant alone, or an antidepressant with a mood
stabiliser found that the risk of patients requiring treatment
for mania was increased almost three-fold by antidepressant
monotherapy.11 The risk of mania requiring treatment was
significantly decreased after three to nine months of concurrent
treatment with a mood stabiliser and an antidepressant.