A Longtitudinal Analysis of Cognitive and Eye Movement Deficits in Alzheimer's Disease.

Higham, Stephen (2006) A Longtitudinal Analysis of Cognitive and Eye Movement Deficits in Alzheimer's Disease. PhD thesis, UNSPECIFIED.

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Abstract

The main purpose of this thesis was to investigate longitudinally, cognitive and eye movement deficits in Alzheimer's disease. A key aspect of the work was to examine the potential utility of saccadic eye movements in the diagnosis of Alzheimer's disease. Study I investigated saccadic error rates and error correction in Alzheimer's disease, other dementias and healthy elderly control participants using reflexive and voluntary saccade paradigms, to identify salient findings for further analysis. Study II explored the fixation offset effect in Alzheimer's disease, other dementias and healthy elderly control participants, to study the attention (fixation) disengagement deficit previously reported in Alzheimer's disease. Study III examined the effects of normal aging and disease, comparing Alzheimer's disease patients and other dementia types with healthy young adult control participants, healthy elderly control participants and Parkinson's disease patients. Study IV assessed the potential effects of acetylcholinesterase inhibitors on baseline data to eliminate medication effects. Study V investigated repeated measures data for salient observations from Studies I and II in Alzheimer's disease patients and healthy elderly control participants over an 18 month period. Study VI evaluated salient saccadic eye movement and neuropsychological assessment variables, with a view to generating regression models that could predict dementia. Alzheimer's disease patients were found to commit inhibition errors that increased in proportion according to the demands of the voluntary saccade task. Error-correction analysis, revealed that a high proportion of errors remain uncorrected in the antisaccade task, a finding apparently specific to dementia. The results were found to be consistent with the notion that the voluntary saccade tasks require selective attention, the facilitation of which is dependent on task goals being sufficiently activated in working memory. The magnitude of fixation offset effect was greater for Alzheimer's disease patients than controls and Parkinson's disease patients at baseline, but the longitudinal analysis showed that this magnitude decreased over subsequent test sessions. The large initial magnitude of fixation offset effect is believed to have been caused by over compensation of volitional compensation strategies at baseline, when the Alzheimer's disease patients had mild dementia. Regression models using antisaccade variables and neuropsychological assessment scores as predictors both performed well. It is feasible that models could be developed that would enable a reduced set of neuropsychological assessments to be used and three predictors from one antisaccade task. The results confirm that the antisaccade task is a useful model paradigm for the study of oculomotor dysfunction in dementia.

Item Type:
Thesis (PhD)
Additional Information:
Thesis (Ph.D.)--Lancaster University (United Kingdom), 2006.
Subjects:
ID Code:
133548
Deposited By:
Deposited On:
02 May 2019 16:35
Refereed?:
No
Published?:
Unpublished
Last Modified:
26 Nov 2020 07:40