Date of Award

Summer 2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Clinical Psychology

First Advisor

Nielson, Kristy

Second Advisor

Hoelzle, James

Third Advisor

Gordon, Nakia S.

Abstract

Alzheimer's disease (AD) is a neurodegenerative pathological process that is thought to begin years prior to observable symptom onset. The hippocampus appears to be particularly vulnerable to the underlying brain pathology of AD. Hippocampal volume is a sensitive measure in predicting conversion from mild cognitive impairment to AD, but less is known regarding the use of hippocampal volume in asymptomatic individuals at risk for AD who eventually decline. The inconsistent findings may, in part, be due to the chosen method of hippocampal segmentation. FreeSurfer (FS) and manual tracings (MT) are two common segmentation techniques that have unique costs and benefits. The present study directly compared hippocampal volumes generated by FS and MT in a longitudinal design assessing cognitively healthy elders, with varying degree of risk for AD, over a 4.5-year period. After 4.5 years, 15 participants demonstrated cognitive decline, while 45 remained stable. The results suggest FS consistently produced larger hippocampal volumes than MT, but neither method distinguished between groups at baseline. Longitudinally, individuals who declined experienced a more progressive pattern of atrophy compared to those who remained stable. These data suggest that hippocampal volume over time may be a useful variable in determining cognitive change over time, with the addition of other known risk factors, such as genetic risk. This study also suggests that in presymptomatic individuals, MT may not provide added benefit over the use of the more cost-effective FS.

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