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Bipolar
Disorder is commonly categorized
as either Type I, when
there are full-blown manic
episodes (not triggered
by medication), or Type
II, when the episodes do
not go beyond ‘hypomanic’.
In addition there are ‘rapid
cycling’ subtypes.
Because there is so much
variation in the severity
and nature of mood-related
problems, the concept of
a bipolar spectrum of subtypes
is often employed, and
sometimes the concept of
a continuum of mood variation
merging in to the ‘normal’ range.
Bipolar disorder is considered
to be a result of complex
interactions between genes
and environment. The disorder
runs in families, with
over two thirds of people
with bipolar disorder having
at least one close relative
with the disorder or with
unipolar major depression,
indicating that the disease
has a genetic component.
Researchers
suggest that abnormalities
in the structure or function
of certain brain circuits
could underlie bipolar
and other mood disorders,
and studies have found
anatomical differences
in areas such as the prefrontal
cortex and hippocampus.
The
nature of personality and
temperament may play a
role.
Some studies suggest
that bipolar patients were
significantly more extroverted,
intuitive, and perceiving,
and less introverted, sensing,
and judging than were unipolar
patients. The “kindling” theory
asserts that people who
are genetically predisposed
toward bipolar disorder
can experience a series
of stressful events, each
of which lowers the threshold
at which mood changes occur.
Eventually, a mood episode
can start (and becomes
recurrent) by itself. Not
all individuals experience
subsequent mood episodes
in the absence of positive
or negative life events,
however.
Individuals
with late-adolescent/early
adult onset of the disorder
will very likely have experienced
childhood anxiety and depression.
Some argue that childhood-onset
bipolar disorder should
be treated early.
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