Causes of bipolar disorder

This fact sheet can be on the “Black Dog Institute” website.

The information in this fact sheet is not intended as a substitute for professional medical advice, diagnosis or treatment.

What this fact sheet covers:
• Genetics
• Brain chemicals
• Environmental
• Medical illness
• Pregnancy
• What is the future for someone with bipolar disorder?
• Where can I get help for bipolar disorder?
• Key points to remember

Introduction
While we don’t yet know exactly what causes bipolar disorder, we do know that it is
primarily a biological illness. However, its onset is often linked to a stressful life event.
And while the causes of bipolar disorder are still unknown, there are a number of
factors that are believed to play a role, including genetics, brain chemicals,
environmental factors and sometimes medical illnesses. We discuss these briefly
below.

Genetics
Bipolar disorder is frequently inherited, with genetic factors accounting for
approximately 80 per cent of the cause of the condition.

If one parent has bipolar disorder, there is a 10 per cent chance that his or her child
will develop the illness. If both parents have bipolar disorder the likelihood of their
child developing the illness rises to 40 per cent.

However, just because one family member has the illness, it is not necessarily the case
that other family members will also develop the illness. Other factors also come into
play.

Brain chemicals
A recent theory about the cause of bipolar disorder is that it is related to abnormal
serotonin chemistry in the brain. Serotonin is one of the neurotransmitters in the
brain, and one that strongly affects a person’s mood. It is thought that the abnormal
serotonin chemistry causes mood swings because of its feedback effect on other brain
chemicals. It is unlikely, however, that serotonin is the only neurotransmitter
involved.

Environmental
While the onset of bipolar disorder may be linked to a stressful life event, it is unlikely
that stress itself is a cause of bipolar disorder. Notwithstanding this, people who
suffer from bipolar disorder often find it beneficial to discover ways of managing and
reducing stress in their lives (as do people without the disorder!).

Again − while not a cause − seasonal factors appear to play a role in the onset of
bipolar disorder, with onset chance increasing in spring. The rapid increase in hours of
bright sunshine is thought to trigger depression and mania by affecting the pineal
gland.

Medical illness
Medical illness is not a cause of bipolar disorder, but in some instances can cause
symptoms that could be confused with mania or hypomania. Some medications and
certain illicit stimulant drugs can also cause manic and hypomanic symptoms.

Pregnancy
For women who are genetically or otherwise biologically predisposed to developing
bipolar disorder, the postnatal period can coincide with a first episode of bipolar
disorder.

What is the future for someone with bipolar disorder?
Like any other medical condition, such as heart disease or diabetes, bipolar disorder is
an illness that requires careful management.

While there is no known cure for bipolar disorder, the good news is that its severity
and the frequency of episodes can be well controlled, reduced or prevented with
medication and other supports, such as psychological therapies.

Where can I get help for bipolar disorder?
Bipolar disorder usually requires diagnosis and treatment by a psychiatrist. However,
if you have not previously sought help for bipolar disorder, as a first step, you should
see your General Practitioner. He or she will either conduct an assessment of you to
find out if you have bipolar disorder, or refer you to a psychiatrist who will conduct
the assessment.

The psychiatrist will develop a management plan in consultation with you and possibly
also your General Practitioner. Depending on the nature of your illness, ongoing
management may be undertaken by the psychiatrist, or by your General Practitioner,
in consultation with your psychiatrist.

Key points to remember
• The causes of bipolar disorder are not conclusively known, but it is a biological
illness whose onset is often linked to a stressful life event.
• Bipolar disorder is frequently inherited.
• Seasonal factors appear to play a role in the onset of bipolar disorder.
• Pregnancy can coincide with a first episode of bipolar disorder in women who
are genetically or otherwise biologically predisposed to developing bipolar
disorder.
• There is presently no known cure for bipolar disorder but with skilled medical
management, the person with bipolar disorder can lead a stable and productive
life, with the condition well controlled.

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