According to the World Health Organization, Depression, also known as Major Depressive Disorder (MDD), is a leading cause of disability worldwide and a major contributor to the global burden of disease. Affecting more than 264 million people worldwide, depression is more than sadness in response to life events and usual mood changes. In order to be diagnosed, the DSM-5 states that the affected person must experience 5 or more symptoms during a consecutive 2-week period, and cause clinically significant distress or impairment in social, occupational, or other area of functioning. In the United States alone, MDD is one of the most common mental disorders, affecting 17.3 million adults in the U.S as of 2017 (NSDUH). While heavily studied, depression has various aspects that have yet to be confirmed, including models depicting emotional reactivity and risk factors, both of which will be discussed later on.
In “Abnormal emotional reactivity in depression: Contrasting theoretical models using neurophysiological data,” Hill et al. look into the emotional responses of those who are diagnosed with MDD. The 3 most prominent models for emotion reactivity depression are as follow: negative potentiation hypothesis, the positive attenuation hypothesis, and the emotion context insensitivity (ECI) hypothesis. The negative potentiation hypothesis states that MDD causes enhanced emotional reactivity to negative stimuli. The positive attenuation hypothesis states MDD causes reduced emotional reactivity to positive stimuli. Lastly, the emotion context insensitivity (ECI) hypothesis states that MDD causes dampening of reactivity to emotional stimuli in the environment broadly, meaning positive or negative. The researchers used structural equation modeling (SEM) techniques on event related potentials (ERPs) to see if ECI is specific to depression or also linked to anxiety by comparing the models through the LPP. The LPP, or late positive potential, is a reliable measure of ERPs, tracking attention to emotionally arousing stimuli. They found that people with MDD but not anxiety experience reduced emotional reactivity to all stimuli, supporting the ECI hypothesis.
While Hill’s research looked at the models for emotional reactivity and supports the ECI hypothesis, it is important to note that no one model has been confirmed. There is much that is still unknown about depression, including risk factors. Depression is influenced by many things, from genetics to life stressors. One thing that was unexpected was the value of happiness as a risk factor for depression. Culturally, the United States places a big emphasis on the pursuit of happiness, and strongly values happiness. Previous studies have already established that highly valuing happiness is associated with lower well-being and decreased happiness. In “Desperately Seeking Happiness: Valuing Happiness is associated with Symptoms and Diagnosis of Depression” Ford et al. test to see if that association translates over to the clinical setting. The researchers used a variety of scales to assess subjects in remission from MDD and healthy controls. The MDD groups reported higher levels of valuing happiness than the control groups, even when controlled for all demographic factors. This also held true when the researchers controlled for current depressive symptoms, indicating that valuing happiness is characteristic of MDD, not associated with its negative symptoms. They also controlled for the general valuing of positive and negative affect and extreme goal pursuit, indicating that valuing happiness is not due to subjects’ wanting to feel missing emotions or any extreme goal pursuit. To simplify, Ford et al., found that valuing happiness is associated with the symptoms and a history of MDD. This study shows that extreme valuing of happiness is a risk factor for MDD.
Personally, I chose these studies because I was surprised by the link between the value of happiness and depression, a particularly melancholic risk factor for a disorder that reduces emotional reactivity for all stimuli. Affected individuals value happiness so heavily, yet react to all stimuli at a reduced level, not feeling happiness to the same extent as healthy individuals. However, the ECI hypothesis is still a hypothesis. More research in depression could lead to a confirmed model, and better treatment. This is an excellent direction for the future, especially considering that only 35-55% patients who undergo treatment ever reach remission, and of those patients, 29% relapse after a single year.
Bibliography:
Ford, Brett Q. et al. “Desperately Seeking Happiness: Valuing Happiness is Associated with Symptoms and Diagnosis of Depression.” Journal of social and clinical psychology vol. 33,10 (2014): 890-905. doi:10.1521/jscp.2014.33.10.890
Hill, Kaylin E. et al. “Abnormal emotional reactivity in depression: Contrasting theoretical models using neurophysiological data” Journal of Biological Psychology, vol. 141 (2019): 35-43
World Health Organization. “Depression.” 30 Jan 2020, https://www.who.int/news-room/fact-sheets/detail/depression
Truschel, Jessica. Depression Definition and DSM-5 Diagnostic Criteria. 25 Sept 2020, https://www.psycom.net/depression-definition-dsm-5-diagnostic-criteria/
(NSDUH) National Survey on Drug Use and Health, “Major Depression.” Feb 2019, https://www.nimh.nih.gov/health/statistics/major-depression
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