All ETDs from UAB

Advisory Committee Chair

Michael Crowe

Advisory Committee Members

Virginia Wadley

H Randall Griffith

Ross Andel

David Clark

Document Type

Dissertation

Date of Award

2012

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

Mild Cognitive Impairment (MCI) is thought to represent the preclinical stage of Alzheimer's disease. Current criteria for amnestic-MCI do not specify the nature of memory impairments, which could be in learning or retrieval of information in verbal or visual domains. While 1.5 standard deviations (SD) below normative samples has been accepted to define cognitive impairment, this standard may be relatively stringent, or may lack specificity to identify mild functional impairment. Baseline data for 71 individuals with consensus-diagnosed MCI enrolled in the Measuring Independent Living in the Elderly Study (MILES) was utilized to investigate patterns of verbal and visual learning and memory, as well as cognitive predictors of functional abilities in MCI. In this sample, verbal memory deficits were the most common learning/memory impairment (62% of the sample), followed by visual learning (49%), visual memory (40%), and verbal learning (38%). A cluster analysis using these measures revealed two groups that were differentiated based on overall severity of memory deficits rather than verbal/visual or learning/recall distinctions. Further, the more impaired group exhibited worse performance on measures of attention and executive functions when compared to the less impaired group. Of note, the mean learning and memory scores for both groups identified were above 1.5 SD cutoffs for MCI. Hierarchical multiple regression modeling was used to investigated cognitive predictors of time to complete Instrumental Activities of Daily Living (IADLs) and accuracy of IADL completion. Although memory and attention predicted overall accuracy of IADLs, Useful Field of View (UFOV) performance was associated with speed of IADL completion. For driving performance, logistic regression analyses revealed that memory severity was not significantly associated with any driving skills. Lower executive functions predicted suboptimal driving skills, whereas lower attention predicted decreased smoothness of driving, speed adjustments, and overall driving performance. Finally, performance-based measures of functional abilities predicted overall driving performance independent of attention and executive functions. The current findings suggest that performance on non-memory tasks is crucial to assess individuals with MCI, particularly in regard to functional abilities. A variety of cognitive and functional measures may be necessary to fully evaluate the functional status of individuals with MCI.

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