Research on Depression and Working Memory

Introduction

Depression is an illness that can affect all aspects of daily life because of its negative impact on thoughts, emotions, energy level, and the focus of this paper, working memory. Depression can have many causes, including the stress generated by a demanding job and other common life activities, challenging family situations and events, hormones, genetics, drug and alcohol use, and personal loss and the resulting grief. Working memory briefly stores information that may be of immediate use during our waking hours. All of us, regardless of age, use working memory to carry out routine daily tasks. For example, a student uses working memory to complete a long division problem. A cook needs working memory to correctly prioritize and mix the ingredients of a recipe. Depression, however, can have a significantly harmful impact on the working memory required for these activities by diverting our focus to negative thoughts and emotions often unrelated to what we are trying to do. This paper will review research on the effect depression has on working memory and will propose research that would assess its specific impact on the working memory of children who experience bullying at school.

Literature Review

Greenwald and Carr (2018) studied the relationship between anxiety, depression, learning problems, and attention problems by administering a variety of tests. Researchers had predicted that anxiety and depression scale scores on the Behavioral Assessment System for Children- Second Edition (BASC-II) and Teacher Rating Scales (TRS) would have a negative correlation with working memory and IQ scores on the Wechsler Intelligence Scale for Children- Fourth Edition (WISC-IV). Questionnaires were filled out by children, teachers, parents/guardians, and school psychologists. The follow-up tests assessed externalizing problems, internalizing problems, school problems, and adaptive skills. Greenwald and Carr found that learning problems were a significant factor in working memory scores. However, as learning problems scores increased, working memory performance scores decreased. The hypothesis of the researchers was deemed correct because anxiety, depression, learning problems, and attention problems scores did not have a negative relationship with IQ scores.

Another term for experiencing mental discomfort or feelings of anxiety or misery is dysphoria. Dysphoric individuals are known to have deficits in their working memory compared to individuals without dysphoria when depressive symptoms are current. Hubbard, Hutchison, Hambrick, and Rypma (2015) studied whether a working memory task with depressive symptoms can result in a decreased performance on a consequent working memory task without depressive symptoms for dysphoric individuals compared to non-dysphoric individuals. They hypothesized that individuals with dysphoria in a working memory task and reading span task would perform poorer on the reading span task compared to individuals with dysphoria in the reading span task and working memory task condition and non-dysphoric individuals in either condition. Participants were asked to complete a reading span task and an effective working memory task back to back to assess whether or not receiving the effective working memory task could affect the performance on the reading span tasks for dysphoric individuals compared to non-dysphoric individuals. Following that, participants were required to complete another set of tests. The tests included a Center for epidemiological studies for depression inventory, Ruminative responses scale, Raven's advanced progressive matrices, Effective working memory task, and Reading span task. Researchers found the results supported their hypothesis. Individuals with dysphoria responded more depressively than individuals without dysphoria. Furthermore, results also showed that individuals with dysphoria scored lower on the working memory tasks compared to people without dysphoria.

Zhang, Xie, He, Wei, and Gu (2018) studied working memory updating on positive, negative, and neutral levels in patients who suffer from depression utilizing the 2-back task. Using the 2-back task, researchers studied working memory of emotional words in depression. However, because this was a pilot study, no specific hypothesis was given. Participants were put into two groups, depressive patients and non-depressive patients. A word would be presented to the participants for eight hundred milliseconds in each trial. Participants were then asked to indicate whether the current word matched another word had been presented two trials earlier. Researchers found that participants with depression had a lower rate and a longer response time for identifying positive words compared to participants who did not suffer from depression. Furthermore, people with depression showed low sensitivity to positive stimuli; meaning, they pay less attention to positive material and have a more difficult time remembering positive events in their lives.

To extend the study, Li, Lu, Wang, and Zhong (2015) studied the difference between emotional working memory and emotional experiences in male and female participants who suffer from depression. Since there are a lot of studies on the effects of sex hormones between males and females, researchers wanted to study the cognitive differences between males and females who suffer from depression. Researchers predicted that female emotional working memory would score higher than in males. In the study, there were pictures of positive, negative, and neutral emotions to examine mood and emotional working memory. During the experiment, pictures appeared for one hundred thousand milliseconds to let participants remember all of the pictures that were being presented. This was followed by, a five thousand millisecond memory retention time. Next, participants were presented with another picture and were asked to respond if the picture appeared in the previous trial. As expected, researchers found that both genders who suffer from depression have memory effects of mood congruence; meaning, the only remember information that is consistent with their particular mood. Also, researchers found that participants with a negative emotional state remember more negative information than positive information, which led to the conclusion that both genders’ working memory for negative emotions was higher than positive emotions. All in all, researchers concluded that there were no significant differences in emotional working memory among participants with depression. However, the female’s level of emotional experience turned out to be higher than in men.

Christopher and MacDonald (2005) studied the impact of depression on working memory performance and to examine which components were affected. The main questions that the researchers had were,

1. 'Is there an impairment of working memory in depression and which elements does it affect,
2. Is another major clinical group also affected and in what ways,
3. How do these groups vary when compared with each other and with normals?' (Christopher et al., 2005).

Researchers hypothesized that there would be a greater difference between depressed and non-depressed group performance in working memory. They also hypothesized that the performance in depressed participants would be more impaired under single-task conditions than the other group. Lastly, researchers hypothesized that the performance gap between the depressed group and the two comparison groups would decrease as a function of increasing task difficulty (Christopher et al., 2005). Participants were asked to complete a set of questionnaires to measure general ability. Next, participants were asked to complete a subset of tasks. These sets consisted of phonological similarity effect, grid recognition, backward letter span, word length effect, consonant trigrams, running memory, and verbal reasoning. However, throughout these tasks, researchers also monitored the participant’s suppression activity. Overall, researchers found that the depressed group showed decrements in all of the tasks. However, researchers said the depressed group performed better under difficult suppression conditions when being compared to easy task instructions (Christopher et al., 2005). Researchers concluded that there was evidence of differences between depressed and non-depressed participants on working memory tasks. Also, the performance in the depressed group showed more impairment under no suppression tasks. Lastly, results showed that performance differed between the depressed group and the two comparison groups as tasks increased.

A significant amount of research has shown that depression has a significant impact on working memory, such as studies by Hubbard et al., 2015; Christopher et al., 2005. In addition, Li et al., 2015 in a related study focused on gender differences and emotional working memory. Other studies focused on the impairment of working memory for emotional stimuli (Zhang et al., 2018). However, only one study focused on the effects of working memory in children (Greenwald et al., 2018). Consequently, more studies are needed on how depression affects children and their working memory. As children grow and develop, they experience difficult situations such as bullying or parental divorce. This research would seek to determine how working memory is affected by depression in children who are bullied. It is hypothesized that working memory is negatively affected more in such children than those who have been diagnosed as clinically depressed.

For this particular research, 40 children would be recruited from middle schools in Maryland’s Prince George’s County and Baltimore County. Incidents of bullying in middle schools are higher than in other grades, possibly because children are forming cliques, “finding themselves”, and simply growing up. The participating middle schools would be Baltimore’s Pine Grove and Walker Mill in Capitol Heights. In addition, 25 clinically depressed children who are getting bullied and are undergoing treatment at an outpatient facility would be recruited with parental permission. Researchers would meet with both parents and students to provide information about the study, explain the goals and benefits, and encourage full participation. Researchers would attempt to select a diverse racial and gender mix of children for participation, with middle school status, exposure to bullying, and clinical depression essential requirements. All participants would be compensated with a $20 VISA gift card.

Conclusion

Considerable research shows clearly that depression harms working memory and can affect emotional working memory (Li et al., 2015). (Zhang et al., 2018) also finds that one aspect of impairment in working memory is depression. Being depressed or having depressive thoughts affects your thought process as well (Hubbard et al., 2015; Christopher et al., 2005). However, there has not been a lot of research on the effects of depression and working memory in children. This current proposed research intends to further examine how depression can affect children who are being bullied. Additionally, this current research may also support the findings on the effects of depression and working memory. It is hypothesized that children who are currently being bullied will have a higher level of impairment in working memory compared to children who are clinically depressed. Researching children who are depressed from being bullied in schools will create awareness of this tragic issue and will also allow other researchers to create more useful programs for young children who are being bullied.