Anne, Michele
(2021)
Autobiographical memory differences among individuals with subclinical depression and PTSD.
PhD thesis, University of Nottingham.
Abstract
Autobiographical memories are complex multidimensional memories an individual has about their past, which are used for bonding, problem solving, creating self-concepts, and emotion regulation. Previous research has found differences in autobiographical memory recall among individuals with clinical levels of depression and post-traumatic stress disorder (PTSD) in comparison to psychological healthy individuals. However, the extent of these differences among individuals with subclinical levels of depression and PTSD, and the mechanisms that may underlie or influence these differences have not been established clearly. These gaps in the knowledge limit our understanding into the type of memory-related difficulties experienced, and whether subclinical samples will likely benefit from similar memory-related interventions as clinical samples.
The current thesis aimed to investigate whether there are differences in various facets of autobiographical memory recall in individuals with subclinical levels of depression and PTSD as compared to psychologically healthy individuals. Investigating different facets of autobiographical memory enables a holistic overview of memory recall to be established for the subclinical populations. In addition, the current thesis also aimed to investigate whether potential mechanisms and factors associated with those differences could explain, strengthen, or weaken the differences and associations observed.
Each chapter in this thesis investigated a different area of autobiographical memory recall. Chapter 2 focused on the retrieval of semantic and episodic components of memory recall. Study 1 in this chapter investigated differences in the characteristics of Cultural Life Scripts (CLS) and Individual Life Stories (ILS) recalled among individuals with subclinical depression and PTSD symptoms, and the role of societal identification. Participants generated events expected to be experienced by a prototypical infant from their culture, as well as events they had (or expect to) experienced themselves, and rated these events on importance, emotional valence, pressure, and perceived ability. They then completed questionnaires measuring levels of depression, trauma, collectivism, and individualism. Results from Study 1 showed that when compared to psychologically healthy individuals, individuals with subclinical depression generated CLS that were less typical, whereas individuals with subclinical PTSD did not have differences in the CLS. Individuals with subclinical depression did not retrieve different ILS, whereas individuals with subclinical PTSD retrieved ILS that were more negative and have higher pressure to achieve. In addition, collectivism moderated the relations of depression with CLS typicality, and depression and trauma with ILS pressure.
Study 2 in this chapter studied whether the differences in CLS typicality observed among people with subclinical depression in Study 1 was linked to differences in knowledge of CLS events or differences in selection of typical CLS events. To examine differences in the knowledge, participants decided whether the events from a list were CLS events or not. To examine difference in the selection, participants also generated events expected to be experienced by a prototypical infant from their culture. They then answered questionnaires measuring depression and trauma symptoms. Results from Study 2 showed that there were differences in the knowledge of CLS events for individuals with subclinical levels of depression, which may explain the differences in typicality of the CLS observed in the previous study.
Chapter 3 examined the type of autobiographical memories retrieved. Differences in recalled memory specificity among individuals with subclinical depression and PTSD symptoms, and whether the CaR-FA-X model (i.e., capture and rumination, functional avoidance, and executive functioning) would underlie those differences were studied. Study 3 in this chapter used minimal instructions to elicit autobiographical memories, whereas Study 4 used specific instructions. Participants retrieved memories in response to emotional cue words and categorized them based on specificity. They then completed executive functioning tasks measuring verbal working memory and inhibition and answered questionnaires measuring depression, trauma, rumination, and avoidant coping levels. For both studies, there were no differences in memory specificity for people with subclinical depression and PTSD as compared to psychological healthy people, regardless of the valence and intensity of the cues. Trauma severity predicted the development of semantic associations in Study 3, and overgeneral memory in Study 4. Components of the CaR-FA-X model did not function as mediators for both studies and as moderators for Study 4, but rumination and inhibition strengthened the relations of depression and trauma with semantic associations in Study 3.
Chapter 4 looked at subjective feelings towards autobiographical memories. Differences in psychological distance among individuals with subclinical depression and PTSD symptoms, and whether memory phenomenology and emotion regulation strategies would underlie those differences were examined in Study 5 in this chapter. Participants described their most positive and negative memories that occurred within the last three years and that occurred more than three years ago and rated these four memories on recollective experience, vantage perspective, emotional intensity, and centrality. They then answered questionnaires measuring levels of depression, trauma, cognitive reappraisal, and expressive suppression. The results showed that there were no differences in psychological distance for those with subclinical depression and PTSD as compared to those who are psychological healthy, regardless of the age or valence of the memory, but depression severity predicted feeling closer to recent negative memories. Recollective experience was shown to explain the associations of depression and trauma with psychological distance of recent negative memories, whereas the other memory phenomenology and emotion regulation strategies did not function as mediators. Emotional intensity moderated the relations of depression with psychological distance of remote positive events, and field perspective moderated the relations of depression and trauma with psychological distance of remote negative events, whereas other memory phenomenology and emotion regulation strategies did not function as moderators.
The findings from the current thesis showed that individuals with subclinical depression symptoms display small differences in the semantic aspects of their memories but not the episodic aspects of their memories, the types of memories they recalled, and how they felt towards the memories. Individuals with subclinical PTSD symptoms, on the other hand, show small differences in the episodic aspects of their memories but not the semantic aspects of their memories, the types of memories they recalled, and how they felt towards the memories. The differences in memory observed from the current thesis were small, and could be attributed to small differences in cognitive areas associated with memory recall. The findings from this thesis improve our understanding into memory recall in subclinical populations, and indicate that memory should be studied in a holistic manner. Possible clinical applications that can be hypothesised from the current theoratical findings are also discussed.
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