Depression is a life altering mental illness that is characterized by feelings of hopelessness and dejection, due to which individuals are not able to feel pleasure or happiness in their lives. According to statistics from the Anxiety and Depression Association of America, Major Depressive Disorder affects 14.8 million American adults in the U.S. every year, which is a significant amount of the population. The concept of high negative activity and low positive affectivity in individuals affected by depression was studied by a researcher and professor at Loyola University Chicago: Dr. Rebecca Silton. Dr. Silton presented her research by first defining what depression is because it has negative connotations associated with it as it is thrown around so loosely. She began her lecture by showing a TED talk given by an American author and lecturer, Andrew Soloman, who stated that "the opposite of depression is not happiness, but vitality." Dr. Silton used this definition of depression to introduce her research because it shows that depression doesn't just affect one's emotions or mood temporarily, but affects their life as a whole.
In relation to her research, Dr. Silton had postulated that anhedonia, which is a distinct feature of depression, is characterized by high negative affectivity and low positive affectivity. In order to examine the interrelation between low positive affectivity and activity in the brain, she performed a study consisting of participants with remitting depression as well as a controlled group of participants without depression. The participants were first asked to fill out a MASQ questionnaire in order to measure whether they presented symptoms of negative or positive affectivity. Afterwards, the participants' brain activity was observed in their resting state as they had electrodes placed on them hooked up to an EEG, which tracked their brain wave patterns. The results from this study indicated that participants with remitted depression exhibited low left prefrontal cortical activity due to high alpha wave activity. From this, they were able to conclude that depressed individuals with low positive affectivity presented low prefrontal cortical activity and high alpha wave activity, which provides implications to how depression may be caused by low activity in the prefrontal cortex.
Similar to this study, another study was recently performed by PhD student, Yael Millgram, and her lab at the Hebrew University in regards to depression. People with depression experience negative emotions and one would think that given the chance, those experiencing depression would let go of their negative emotions; however, this did not appear to be the case. In this study, individuals with depression were studied to find that when given the opportunity to manipulate their emotions, they did not let go of their negative emotions and held onto their depressive thoughts, which prevented them from being "cured" of depression. This study was performed by first screening the participants for symptoms of depression. They were then divided into two categories of depressed and non-depressed individuals, similar to Dr. Silton's study. All of the participants were then asked to complete an image selection task in which pictures were flashed for a few seconds in front of each participant and they were asked to press a button if they wished to view the image again or press a different button if they wished to see a black screen instead. The images that were flashed before the participants consisted of 10 happy images, 10 sad images, and 10 images that were emotionally neutral. These images were each supposed to induce a certain emotion with respect to the emotion conveyed by the image. From the results it was observed that the participants displaying symptoms of depression chose to view and re-view sad images more often than those without depressive symptoms. This study was repeated more than once with a different variables, such as music, and they achieved the same result. This indicated that the individuals with depression themselves were not motivated to decrease their negative emotions, as they denied the strategies that were presented to them to decrease their emotional response to positive stimuli, which kept them from escaping their depression.
The Millgram study relates to that of Dr. Silton's in that it acknowledges the idea that high negative affectivity and low positive affectivity are what cause depression. The Millgram study builds upon that of Dr. Silton's in that it points out why certain forms of treatment may not work for treating depression due to the fact that the depressed subjects are not able to accept positive emotions into their lives, which prevents them from getting "cured" of depression in a sense. In addition, according to Dr. Silton's study, the activity in the prefrontal cortex, which is a region in the brain that is associated with executive functions (I.e. decision making), is observed to be low in individuals with depression, which explains why the depressed participants in the Milgram study chose the negative stimuli that induced unhappiness. The Milgram study, equipped with studies such as Dr. Silton's on positive affectivity, provide great implications to further studies regarding depression in the future, which may ultimately lead to finding a cure for such a debilitating mental illness.
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