Risk factors for bipolar disorder | Mental health | NCLEX-RN | Khan Academy


– [Voiceover] There are a
number of different theories about the cause of Bipolar Disorder. As with everything else though, there is probably no one cause. Instead there are many
causes that interact with each other in complicated ways. And I even think that the term cause is problematic in this situation,
because it kind of implies that everyone who is
exposed to X, Y and Z causes will definitely wind
up with this disorder, but that isn’t the case either. Think about seasonal allergies. Multiple people might
be exposed to pollen, but not everyone has them. It depends on certain factors like your individual immune system. And also behavioral things,
like where you live. So while in certain
situations pollen might be required for certain
seasonal allergies to exist there are many things that
can increase or decrease the likelihood that you’ll feel sick. And so in this case, it
might be more appropriate to talk about risk factors
than to talk about causes. And that’s true of
bipolar disorder as well. So we are going to be
talking about things that increase the likelihood that someone will develop bipolar disorder,
but aren’t guaranteed causes. We’ll specifically be looking
at biological risk factors, psychological risk factors,
and environmental risk factors. And in terms of these
biological risk factors I’m going to further divide them into genetic risk factors,
neurochemical imbalances, and differences in brain
structure and function. In terms of genetics, family
studies, twin studies, and adoption studies have
all shown that there is a very strong genetic
component to bipolar disorder. Even more so than for depression. In fact, someone who has a family member with bipolar disorder is actually 10 times as likely to have the disorder themselves as compared to the general population. We know that adopted
children are more similar to their biological parents
than their adoptive parents in terms of bipolar
rates, and this indicates a genetic cause rather
than an environmental one. We also know that identical
twins have more similar rates of the disorder than fraternal
twins or other siblings. But once again, this isn’t a guarantee. Rates are higher for identical twins, but they are not identical. One identical twin having
bipolar disorder does not 100% guarantee that the other
twin will have it as well. It just increases the likelihood of it. So while genes certainly do play a role, the situation is pretty complicated. There isn’t just one
bipolar gene that guarantees that someone will wind
up with bipolar disorder. In terms of neurochemical imbalances, we know that individuals
with a related disorder, major depressive disorder,
we know that they show decreased levels of certain
monoamine neurotransmitters. And this includes serotonin,
norepinephrine, and dopamine. And so it’s been hypothesized
that increased levels of these neurotransmitters
might be related to mania. However, other researchers disagree and think that this
model is too simplistic. So this is an area of active research, and knowledge about the
neurochemical underpinnings of bipolar disorder will
continue to evolve over time. We may not be totally sure what’s going on at the neurochemical level,
but we can use structural and functional imaging to look
at neurological differences between individuals with bipolar disorder and individuals without it. For example, some studies
have found differences in functioning in the prefrontal cortex, which is the area of the brain that deals with higher order cognition. Other studies also look at
changes in the lymbic system, or the area of our brain
that process emotion. There is also some evidence
that individuals with bipolar disorder show
an increase in volume in the ventricles in their brain. These are the cavities toward
the center of the brain where cerebral spinal fluid
is produced and stored. Another biological factor might be disturbances in circadian rhythms. During a manic episode an
individual has a ton of energy and they feel a decreased need for sleep. And while we tend to think
of these things as symptoms of bipolar disorder, it is possible that these circadian rhythm
disturbances might somehow be a cause of the disorder
rather than a symptom. Now lets move on to talk about
psychological risk factors. One thing that scientists
have noticed is that individuals with bipolar
disorder tend to have other psychological disorders as well. So it’s comorbid with other conditions. This includes things like
anxiety disorders, like generalized anxiety disorder
and social anxiety disorder. These individuals are
also more likely to have substance use disorders, to
abuse drugs and alcohol, but it’s unclear if that’s something
that naturally co-occurs with bipolar disorder or
something that is caused by it. Because it’s possible that
individuals with bipolar disorder might use substances more because they’re trying to self-medicate. So that, rather than any kind
of biological predisposition, could be driving the effect. This is kind of true for
all of these disorders. We might see them at the same time, but we don’t really know
if one triggers the other. And we don’t know if there’s any kind of common biological cause. In general though,
researchers believe that these psychological factors aren’t
the most important triggers for bipolar disorder, and that
environmental risk factors might play a much larger role. Going through a major
life stressor is one of the greatest predictors
for a manic episode, and this seems to be especially true for stressors related
to social interactions. But please note that this does not mean that going through something
stressful like a divorce will suddenly cause someone
to develop bipolar disorder. Instead we’re saying that they
can trigger manic episodes for individuals who are already at risk. Another thing I want to note is that these stressful life events
aren’t just the things that you might normally think of when
you think about stressors. So it might be helpful
when you see this word to mentally replace it
with major life changes. So these stressors could
include losing a job, but they could also
include starting a new one, or going to college, or getting married. There also seem to be a number of other environmental factors that
can lead to manic episodes in people who are already at risk. For example, taking
certain antidepressants can actually trigger a manic episode. This is one of the many
reasons why people who go on antidepressants, specifically SSRIs, are carefully monitored
by their physicians. So I’ve separated these risk factors into biological, psychological,
and environmental factors, but in order to really have a
comprehensive picture of this you need to think of all
of them as being related to each other, or building on each other. So if I had to give you one kind of take-away line for this video, if I had to give you some
kind of hard and fast cause, I would say that bipolar
disorder is caused by a biological predisposition
in combination with specific psychological
and environmental factors.

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