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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