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Abstract
A rising interest in Quality of Life (QoL) research has occurred in the context of increasing numbers of older adults, projections of dementia prevalence, policy interest to reduce health expenditure, and the desire for positive ageing. Coupled with this has been the advancement of early interventions as a means to preserve independence, improve cognition and promote QoL. Evidence from epidemiological studies and clinical trials suggests that the introduction of cognitive and physical interventions in adults with mild cognitive impairment (MCI) may improve cognition. However, to date there has been limited investigation of QoL and psychological wellbeing (PWB) outcomes in these studies.
The objective of this thesis was therefore to investigate PWB and QoL in adults with MCI. This research is based upon published literature as well as data from the Study of Mental Activity and Regular Training (SMART) Trial, a randomised cognitive and resistance training trial on 100 community-dwelling adults with MCI. Four investigations were performed. Firstly, meta-analyses of QoL and PWB outcomes from randomised controlled trials of physical exercise and cognitive training in MCI indicated limited benefit for QoL and PWB outcomes. Secondly, empirical analyses of a theoretical model of PWB, using cross sectional baseline data from the SMART trial, predicted 61% of the variance of PWB in MCI. Memory concern and cognitive deficits were identified as significant predictors of PWB, along with negative affect and QoL. Thirdly, linear mixed model analyses of SMART physical and cognitive intervention found that mental health-related QoL and Purpose in Life subscale within PWB domain improved following combined intervention. By contrast, isolated cognitive or physical interventions had no significant benefit on any component of QoL or PWB. Lastly, regression analyses indicated that improvement in cognitive function after the interventions was not associated with a reduction in memory concern or improvement in QoL or PWB. Overall, this thesis demonstrated that QoL and PWB in MCI have multiple influences, and that interventions designed to improve cognition do not necessarily improve PWB. Clinical implications from this research are discussed in terms of the development of early intervention programmes in MCI and future research studies.