Executive functions and dual-task ability in healthy ageing and in Parkinson's disease
Sanderson Rebecca Dissertation 2011.pdf (392.9Kb)
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Abstract Objectives: First, to assess memory and executive ability in healthy older adults, relative to young controls, in order to determine the pattern of normal age-related decline. Second, to compare this healthy ageing profile with the pathological ageing profile of Parkinson’s disease (PD) patients. Methods: A between-subjects quasi-experimental design was used to explore performance on a comprehensive range of memory, executive and dual-tasking (DT) measures in 14 PD patients, 27 younger healthy controls and 29 older healthy controls. All older participants were screened for dementia using the Mini-Mental Status Examination, and PD patients were rated on a number of disease-specific variables, such as severity, medication and age of onset. Results: Relative to the younger healthy adults, older healthy adults performed significantly worse on two out of three executive measures: updating and inhibition, but not on switching. PD patients also performed significantly worse than younger adults on updating and inhibition, but not switching. PD patients did not score significantly different from older controls on any measure, even when the effect of age was partialled out, and DT ability did not differ significantly between any of the three groups. Disease severity was unrelated to all measures, although age of onset interacted with memory and updating. Conclusion: The cognitive profile of healthy ageing was broadly in line with expectation, as it shows evidence of robust DT ability despite decline in other executive functions. However, the profile of executive decline in PD was found to be no different to that of healthy ageing. Moreover, there was no evidence for DT impairment in PD. Some of these results must be treated with caution, partly due to methodological concerns, but also because there appears to be a certain amount of heterogeneity in the Parkinson’s cognitive profile. In particular, the size of this patient sample may have been better suited to an in-depth case-study approach, to build up a more detailed profile of deficits and patterns in each individual.