The Relationship Between Mild Cognitive Impairment and Mood in Older People

Abstract

Mild cognitive impairment (MCI) has received increasing attention since the early 1990s. However, considerable controversy exists over exactly how the concept of MCI is defined and measured, and the implications of assigning or receiving a diagnosis of MCI. There is evidence of a link between MCI and mood, but empirical work remains conflicted and inconclusive. The first chapter provides an overview of the MCI concept and highlights some of the issues surrounding its definition. Chapter 2 provides a detailed description of the methodology and background to the empirical work presented in Chapters 4-6. A systematic review of the literature forms the third chapter of this thesis and establishes the need for further study into the relationship between MCI and mood. Chapter 4 makes use of data from the first Cognitive Function and Ageing Study (MRC-CFAS I) to investigate the role of subjective memory complaints (SMC) in the relationship between MCI and mood over a two year period. The results indicated that SMC may be related more strongly to mood than to objective cognitive performance, which raises questions about whether SMC should be included as a criterion in the MCI definition. Chapter 5 clarifies these findings using data from a contemporary cohort in the Cognitive Function and Ageing Study Wales (CFAS Wales). Chapter 6 investigates the role of health in the relationship between MCI and mood, again using data from CFAS Wales. The findings suggest that health problems constitute a risk factor for developing depression and anxiety, which may in turn affect cognitive functioning. This presents a useful opportunity for intervention to improve the quality of life for older people by improving their physical health, or improving the management of long-term conditions. Social networks were investigated as an influential factor in the relationship between MCI and mood, using data from CFAS Wales. Whilst increases in social network size were associated with fewer mood problems and increased cognitive functioning, they did not moderate the relationship between the two. However, this finding still showed that having more social contacts is beneficial and important to the quality of life of older people. The last chapter presents a discussion of the findings in relation to each of the research questions outlined in Chapter 1. The chapter also includes a commentary on the methodological considerations that were faced when developing this thesis, the implications of the findings and directions for future research.