Wednesday, May 4, 2016

The Invisible Disease

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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