All ETDs from UAB

Advisory Committee Chair

Rex Wright

Advisory Committee Members

Randall Griffith

David Clark

Michael Crowe

Virginia Wadley

Document Type

Dissertation

Date of Award

2010

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

This study examined the effect of challenge difficulty on cardiovascular responses in patients with Alzheimer's disease and amnestic mild cognitive impairment. It extended from a model characterizing the determinants and cardiovascular consequences of effort in people confronted with performance challenges. One component of this model holds that ability has the potential to accentuate, attenuate, or have no effect on cardiovascular responses. Specifically, lower ability should accentuate cardiovascular responses so long as performers' view a challenge possible and worthwhile. However, lower ability should attenuate cardiovascular responses when it leads to the perception that a challenge is excessively difficult or impossible. The third outcome is that ability should have no effect on cardiovascular responses when it leaves unaltered the perception that a challenge is excessively difficult or impossible. The current study extended this analysis to Alzheimer's disease and mild cogni-tive impairment under the premise that their neuropsychological deficits would affect cardiovascular responses analogously to lower ability. Cardiovascular responses and performance (accuracy) measures were collected as participants performed cognitive challenges of low, medium, and high difficulty. Participants also rated the subjective dif-ficulty of each challenge. Unfortunately, data collection on the Alzheimer's disease group was discontinued due to low recruitment rate. Contrary to expectations, challenge difficulty did not significantly influence blood pressure responses in patients with mild cognitive impairment. Controls, however, showed the expected increase in blood pressure responses as challenge difficulty in-creased. Subjective ratings of challenge difficulty increased across the low, medium, and high difficulty challenges and were comparable between patients with mild cognitive im-pairment and controls. Accuracy decreased as challenge difficulty increased, and patients with mild cognitive impairment were less accurate than controls. One tentative interpretation of the results is that patients with mild cognitive im-pairment can accurately appraise relative differences in challenge difficulty but have problems adjusting their difficulty appraisals to account for their neuropsychological weaknesses, even when their performance suffers. The cardiovascular response data suggest that patients with mild cognitive impairment may not deploy compensatory effort, perhaps because they may not appreciate challenges as more difficult than their cog-nitively intact counterparts. Other alternative explanations are presented and discussed.

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