More times than not, people tend to say the phrase “I’m so
depressed” without really understanding what the term really means. There is so
much more to depression than just feeling immensely sad. Depression is one of
the most common mental health disorders in the United States. Depression can be
caused by many different factors; these can be anywhere from genetics to environmental
factors such as stress or trauma. Repeated exposure to stressful situations can
increase the risk of developing depression, especially if the stress is not
dealt with in the proper way. Everyone has dealt with stress in some way shape
or form, in fact the right amount of stress is actually healthy in one’s daily
life.
Dr. Rebecca Silton, professor at Loyola University Chicago
recently spoke about how depression is affected by low positive affect (PA). In
order to diagnose someone with depression, they must experience five of the
nine criteria listed in the DSM V, for at least two weeks. She discussed how individuals with depression
lack experiencing and savoring pleasure. This is commonly referred to as
anhedonia. According to Dr. Silton, anhedonia is the reduced ability to
experience pleasure in day to day life. In her study, she assessed how PA and
prefrontal brain activity is associated with remitted depression. She concluded
from her findings that low levels of PA and high levels of prefrontal alpha
produce a diathesis for depression. Her study suggests that high levels of frontal
alpha illustrate a risk for depressive episodes.
Recently I encountered an article written by Robert Sapolsky
in the Wall Street Journal titled, “Stress Starts Up the Machinery of Major
Depression.” This article discussed how stress induces anhedonia which is a
classic hallmark of depression. The ability for one to feel and pursue pleasure
is reflected by the neurotransmitter dopamine. Researchers studied this using
mice by putting them in a cage with an unfamiliar object such as a ball. When
the mouse initially encounters the ball it arouses the nucleus accumbens to
release a molecule called CRF. CRF then boosts dopamine release. When the
researchers exposed the mouse with sustained stress over the course of a few
days they noticed a few changes. The CRF no longer boosted dopamine release,
and the mouse avoided the object. This stress led to an anhedonic state which
lasted in the mice for three months.
All in all, I have learned a lot form both Dr. Silton’s
lecture as well as the article by Robert Sapolsky. It’s really interesting to
see how different factors such as low PA and stress can lead anhedonia which
overall leads to depression.
References:
Sapolsky, Robert
M. "Stress Starts Up The Machinery of Major Depression." The
Wall Street Journal. N.p., 28 Apr. 2014. Web. 03 May 2016.
<http://www.wsj.com/articles/SB10001424052702304734304579517953987157822#:TL-COKP6eG8XKA>.
Silton, L. R.,
Polnaszek, K. L., Dickson, A. D, Miller, A. G., Heller, W. Low positive affect
is associated with reduced prefrontal cortical activity in remitted depression. Psychophysiology, 1-31.
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