Cognition in Major Depressive Disorder: Perceptions of Ability, Depressive Thinking, and Performance in Daily Life

Abstract

Individuals living with major depressive disorder experience functional disability and cognitive difficulties in the mild to moderate range. These impairments are associated with functional disability, worsen with repeated episodes of depression, and persist outside of depressive episodes. While cognitive deficits are important in depression, we have several gaps in our understanding of these deficits. Individuals with depression tend to overestimate the degree of their cognitive impairment and this is associated with difficulties with everyday functioning and lower quality of life. However, we do not currently understand why individuals with depression overestimate impairments and what the consequences of this may be. Traditional assessment methods may not capture the nuance in cognitive performance in depression and novel assessment tools may help us to better understand how these constructs manifest in daily life. The objective of this dissertation was to explore the predictors of the discrepancy between subjective and objective cognitive ability, and to explore cognitive performance and its predictors in daily life in individuals with depression. In Chapter 2, we explored why individuals with depression overestimate their cognitive impairments and found that depressive thinking predicted the tendency to overestimate cognitive impairments. We also found that despite no significant differences in objective performance, individuals with depression underestimated their ability to perform on the easiest level of a cognitive task relative to healthy controls. Further, we found that the tendency to overestimate how cognitively impaired one is mediates the relationship between objective cognitive ability and withdrawal from cognitive challenge in daily life. Chapter 3 presents longitudinal data exploring cognitive performance in the context of daily life using novel cognitive tasks developed to use with Experience Sampling Methods (ESM). Findings were contrary to hypotheses and demonstrated that higher negative affect was associated with better cognitive performance and participants were accurate in perceiving their performance on cognitive tasks. These results highlight the importance of exploring perceptions of ability in depression, even if they are discrepant from objective assessments, and highlights the potential utility of novel ESM cognitive tasks to explore these constructs in daily life for individuals experiencing depression.