Gene E Alexander

PMID: 11809161;Abstract:

Objective: The specificity of magnetic resonance imaging (MRI)-based hippocampal measurements in detecting Alzheimer's disease (AD) pathology is reduced by an age-related reduction of the hippocampus volume. We propose an adjustment for this age effect to increase the diagnostic accuracy of hippocampal volumes in AD. Method: Using an orthogonal rotational transformation of the coordinate system, values of MRI-determined volumes of hippocampus-amygdala formation (HAF) were transformed according to the age effect in 27 AD patients and 28 age- and sex-matched healthy control subjects. Results: The age transformation increased the diagnostic accuracy of HAF volumes in the study sample and in an independent sample from the literature. The age-transformed HAF volume predicted AD in a subject with mild cognitive impairment (MCI) with later biopsy-confirmed AD. Conclusion: Age transformation may provide an easily applicable method to increase the clinical diagnostic accuracy of hippocampal measurements by considering the effect of aging on hippocampus volume. Copyright © 2002 Elsevier Science B.V.

PMID: 10828377;Abstract:

Alzheimer's disease, the most common form of dementia in the elderly, is characterized by the progressive, global and irreversible deterioration of cognitive abilities. The development of positron emission tomography (PET) methodologies has made it possible to study the in vivo brain metabolic correlates of human cognitive and behavioral functions. Moreover, as PET scan examinations can be repeated, the progression of the neuropathological process and its relation to cognitive dysfunction can be followed over time. In an effort to understand the changes in neural function that precede and accompany onset of dementia and their relation to clinical manifestations, in the last several years, we have conducted clinical, neuropsychological and brain metabolic studies in groups of Alzheimer's disease patients at different stages of dementia severity or with distinct clinical pictures and in populations at risk for developing the disease. Here, we discuss the main findings and implications obtained from these studies. Copyright (C) 2000 Elsevier Science B.V.

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PMID: 10199337;Abstract:

Background: Positron emission tomographic studies of patients with Alzheimer disease (AD) suggest a loss of metabolic functional interactions between different cortical regions. Atrophy of the corpus callosum as the major tract of intracortical connective fibers may reflect decreased cortical functional integration in AD. Objectives: To investigate whether regional atrophy of the corpus callosum is correlated with regional reductions of cortical glucose metabolism, as shown by positron emission tomography, and whether primary white matter degeneration is a possible cofactor of corpus callosum atrophy in AD. Patients and Methods: We measured total and regional cross-sectional areas of the corpus callosum on midsagittal magnetic resonance imaging scans from 12 patients with AD and 15 age-matched control subjects. Regional cerebral metabolic rates for glucose in cortical lobes were measured by positron emission tomography using fludeoxyglucose F 18. White matter hyperintensities were rated in T2-weighted magnetic resonance imaging scans. Results: The total cross-sectional area of corpus callosum was significantly reduced in patients with AD, with the most prominent changes in the rostrum and splenium and relative sparing of the body of the corpus callosum. Frontal and parietal lobe metabolism was correlated with the truncal area of the corpus callosum in AD. The ratios of frontal to parietal and of frontal to occipital metabolism were correlated with the ratio of anterior to posterior corpus callosum area in the group with AD. White matter hyperintensities did not correlate with corpus callosum atrophy in the patients with AD. Conclusion: The regional pattern of corpus callosum atrophy correlated with reduced regional glucose metabolism independently of primary white matter degeneration in the patients with AD.

PMID: 17218903;Abstract:

INTRODUCTION: Apolipoprotein E (ApoE) genotype and aerobic fitness are each associated with cognitive performance in older adults. However, their potentially interactive effects on cognitive performance have not been examined. PURPOSE: The primary purpose of this study was to determine whether ApoE genotype and aerobic fitness interact to uniquely impact memory performance and executive functioning. A secondary purpose was to examine the interactive effects on other measures of cognition to provide a more comprehensive assessment of cognitive abilities across a broad range of functions. METHODS: Community-dwelling, cognitively normal older women (N = 90) provided blood samples to allow for assessment of ApoE genotype, completed cognitive tests, and performed a maximal aerobic fitness test. Primary outcome variables were the auditory verbal learning test (AVLT), the complex figures test (CFT), and the Wisconsin card-sorting task (WCST). Secondary outcome variables were the block design test and the paced auditory serial addition task (PASAT). RESULTS: Regression analyses indicated that aerobic fitness was associated with significantly better performance on measures of the AVLT, the CFT, and the PASAT for the ApoE-ε4 homozygotes. CONCLUSION: The preliminary findings from this study support the possibility that aerobic fitness is positively associated with the memory performance of those individuals at most genetic risk for Alzheimer disease. ©2007The American College of Sports Medicine.