According to research by Dahyeon Kim and K. Lira Yoon (2020), a cognitive bias might keep a negative mood amongst individuals with depression. Individuals with major depressive disorder (MDD) reported less happiness when remembering positive memories but more sadness when recalling negative memories than healthy controls.
A previous study pointed out differences in the emotional responses to personal memories when comparing people with elevated depressive symptoms to healthy individuals. In the second group of people, the intensity of the positive feelings when remembering pleasant memories outdid the negative emotions when remembering unpleasant memories. When considering individuals with depressive symptoms, the intensity of the emotional responses was the same whether they remembered happy or unhappy memories from their personal histories.
Kim and Yoon interviewed 76 people, and 30 of them were diagnosed with major depressive disorder. The other 46 populated the control group. The study involved the participants in recalling three events from their past (their happiest, saddest, and most anxious moments) and answering two key questions after completing the description of each memory.
The researchers invited them to rate the level of happiness when the event initially took place and reflect on it during the interview. They used the same approach for evaluating sad memories. For the anxious memory, they rated the intensity of their anxiety then and now.
The MDD group expressed more sadness when reflecting on negative memories and less happiness when reflecting on pleasant memories. This effect did not emerge when recalling the anxious memories, suggesting that this differential fading of emotional responses to memories was specific to sad memories.
According to Beck‘s cognitive model of depression, people with depression show a bias when processing negative over positive information about themselves (Beck, 2002). Considering the negative schemas (Beck, 2002) of people with MDD, the saddest autobiographical memories may align with their current worldview (Kim & Yoon, 2020). The authors stated that the saddest autobiographical memories might seem more relevant, resulting in more intense emotional responses in the MDD group. On the other side, the happiest autobiographical memories may contradict their current negative worldview, impeding the experience of more intense happiness in individuals with MDD (Kim & Yoon, 2020).
Kim, D., & Yoon, K. L. (2020). Emotional response to autobiographical memories in depression: less happiness to positive and more sadness to negative memories. Cognitive Behaviour Therapy, 49(6), 475-485.