Wednesday, May 4, 2016

Examining the Relationship between Cannabis Use & Depression

With increasing rates of clinical depression and the recent changes in legislation regarding marijuana, scientists have gained increased access to conducting research involving cannabis in order to better understand its short and long term effects on the brain. Depression has been historically considered as one of the many long-term negative effects associated with individuals who abuse cannabis. As we continue to better understand how depression affects the brain, this opens the door to gaining greater insight of the relationship it has with cannabis abuse. For example, a recent study published in Journal of the American Medical Association of Psychiatry (JAMA Psychiatry) challenges prior research that associates depression with individuals who heavily abuse marijuana.  
            On May 3, 2016, Loyola students had the opportunity to attend a neuroscience seminar by Dr. Rebecca Silton, a psychology professor at the university. In her lecture, Dr. Silton discussed the research conducted in her lab regarding low positive affect and the association it has with reduced prefrontal cortical activity in the brain and clinical depression. Positive affect refers to the extent to which one can experience positive or happy emotions. Dr. Silton’s lab conducted a mood and anxiety questionnaire to paid research volunteers to determine the relationship between positive affect levels and left prefrontal alpha activity. The goal of this study was to determine how positive affect plays out with depression and its remittance.
Depression, according to the DSM V, has 9 qualifying symptoms for diagnosis. Any 5 of these symptoms can be met in order to get diagnosed with clinical depression. One of these conditions, as described by Dr. Silton, is anhedonia, which refers to the inability or lack of experiencing pleasure from things that were previously rewarding or pleasurable. Low positive affect has been associated with anhedonia and Dr. Silton’s particular study found that low positive affect was associated with people diagnosed with depression due to the high left prefrontal alpha activity observed in the brain of these individuals.
With increasing support for legislation and rising number of individuals using cannabis both recreationally and medicinally, it is important for us to gain accurate and reliable information about the effects of cannabis abuse and its relationship with depression through research studies on the brain. Cannabis is a drug that causes the user to feel euphoric by increasing dopamine levels in the brain. Contrary to the traditional understanding of depression as being associated to individuals who regularly abuse cannabis, a recent study published in JAMA Psychiatry challenges this idea. The study published in April 2016 examined 35,000 U.S. adults who participated in this study. The researchers recorded the participant’s marijuana use over a 3 year time frame and noted any mental health issues. Using statistical analysis, the study found no significant relationship with cannabis use and depression or anxiety disorders. However, the study did find an association between marijuana use and later substance-use disorders. In other words, someone who uses the drug will generally become more inclined to try more drugs whether it’s alcohol, tobacco or more cannabis.
With anhedonia and depression being linked to low positive affect, one may wonder if marijuana use, on the other hand, can be associated with high positive affect. Since low positive affect refers to reduced pleasure and sad emotions and is associated with depression due to low prefrontal alpha activity, one may wonder if attributes of high positive affect, which refers to euphoria and happy emotions, can be seen in brain activity associated with cannabis use. Just like how low positive affect is associated, not only with depression, but also future depressive episodes, cannabis use has been found to increase the likelihood of future abuse. While cannabis use may make a user perceive elevated positive affect while under the influence, the relationship it has with the left prefrontal brain activity remains unclear. Since high prefrontal alpha activity is associated with depression and low positive affect, one may question if low prefrontal alpha activity is associated with cannabis use and high positive affect. While the answer to this question remains unclear, with recent changes in legislation in favor of marijuana legalization increasing access to the drug, one can only expect us to gain a better understanding of how marijuana affects the brain and its relationship with depression.

Works Cited:

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.

Ingraham, Christopher. "Study: Smoking Pot Doesn’t Make You Anxious or Depressed." Washington Post. The Washington Post, 17 Feb. 2016. Web. 04 May 2016. https://www.washingtonpost.com/news/wonk/wp/2016/02/17/study-smoking-pot-doesnt-make-you-anxious-or-depressed/


Blanco C, Hasin DS, Wall MM, et al. Cannabis Use and Risk of Psychiatric Disorders: Prospective Evidence From a US National Longitudinal Study. JAMA Psychiatry. 2016;73(4):388-395. doi:10.1001/jamapsychiatry.2015.3229.

Images: 
http://www.treatment4addiction.com/blog/wp-content/uploads/Weed-and-Depression-300x210.jpg
http://img.medscape.com/thumbnail_library/dt_150608_brain_marijuana_cannabis_800x600jpg.jpg

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