There is an urgent need to understand the biological and functional changes associated with brain aging, particularly when considering that age is the most potent risk factor for developing Alzheimer's disease (AD). Myelination and speed of mental processing both improve up to the mid-30's then breakdown or deteriorate progressively with advancing age. The similarity in trajectory between these two processes leads to the hypothesis that myelin breakdown may underlie the age-related slowing in cognitive speed. Apolipoprotein E4 (ApoE4) genotype increases the likelihood of developing AD and decreases age of onset. In healthy adults, presence of ApoE4 allele is associated with more rapid age-related cognitive deterioration while ApoE2 allele mitigates against cognitive decline. Cross-sectional data has demonstrated differential myelin breakdown in association with ApoE genotype with ApoE4 carriers manifesting more severe myelin breakdown. This proposal aims to investigate 1) the prospective change in myelin breakdown with age, 2) the relationship between prospective changes in myelin breakdown and processing speed, and 3) the effects of genetic markers on the prospective changes in biological and cognitive processes. We hypothesize that myelin will breakdown significantly with age;that myelin breakdown will be related to a decline in cognitive speed, and genetic status will modulate this structural-functional relationship. A cohort of 152 healthy elderly subjects underwent MRI and neuropsychological testing, producing some of the results summarized above. We plan to re-contact these subjects to repeat the imaging and cognitive testing using the same imaging protocol and test battery as the baseline evaluation. The inter-assessment interval will be about 6 years. This project will provide a rich source of longitudinal data that can be used to address questions beyond its major focus, such as predicting progression into clinically significant cognitive deficits (i.e., mild cognitive impairment;MCI).

Public Health Relevance

LAY LANGUAGE SUMMARY: By the time that a patient is diagnosed with MCI, they already have significant cognitive deficits and a substantial portion of such patients will develop Alzheimer's disease, which affects millions of people in the US and costs the healthcare system over $100 billion annually. This project has the potential to identify the interaction of imaging and genetic factors in predicting age-related cognitive decline leading to earlier implementation of clinical intervention or preventive efforts.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Mentored Patient-Oriented Research Career Development Award (K23)
Project #
5K23AG028727-05
Application #
8263039
Study Section
National Institute on Aging Initial Review Group (NIA)
Program Officer
Wagster, Molly V
Project Start
2008-05-15
Project End
2014-01-30
Budget Start
2012-05-01
Budget End
2014-01-30
Support Year
5
Fiscal Year
2012
Total Cost
$165,231
Indirect Cost
$11,731
Name
University of California Los Angeles
Department
Neurology
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Hsiao, Julia J; Lu, Po H; Grill, Joshua D et al. (2015) Longitudinal declines in instrumental activities of daily living in stable and progressive mild cognitive impairment. Dement Geriatr Cogn Disord 39:24-Dec
Lu, Po H; Lee, Grace J; Shapira, Jill et al. (2014) Regional differences in white matter breakdown between frontotemporal dementia and early-onset Alzheimer's disease. J Alzheimers Dis 39:261-9
Lee, Grace J; Lu, Po H; Mather, Michelle J et al. (2014) Neuroanatomical correlates of emotional blunting in behavioral variant frontotemporal dementia and early-onset Alzheimer's disease. J Alzheimers Dis 41:793-800
Lee, Grace J; Lu, Po H; Medina, Luis D et al. (2013) Regional brain volume differences in symptomatic and presymptomatic carriers of familial Alzheimer's disease mutations. J Neurol Neurosurg Psychiatry 84:154-62
Lu, Po H; Lee, Grace J; Tishler, Todd A et al. (2013) Myelin breakdown mediates age-related slowing in cognitive processing speed in healthy elderly men. Brain Cogn 81:131-8
Kang, Christine; Lee, Grace J; Yi, Dahyun et al. (2013) Normative data for healthy older adults and an abbreviated version of the Stroop test. Clin Neuropsychol 27:276-89
Lee, Grace J; Lu, Po H; Hua, Xue et al. (2012) Depressive symptoms in mild cognitive impairment predict greater atrophy in Alzheimer's disease-related regions. Biol Psychiatry 71:814-21
Lu, Po H; Thompson, Paul M; Leow, Alex et al. (2011) Apolipoprotein E genotype is associated with temporal and hippocampal atrophy rates in healthy elderly adults: a tensor-based morphometry study. J Alzheimers Dis 23:433-42
Lu, Po H; Lee, Grace J; Raven, Erika P et al. (2011) Age-related slowing in cognitive processing speed is associated with myelin integrity in a very healthy elderly sample. J Clin Exp Neuropsychol 33:1059-68
Lu, P H; Edland, S D; Teng, E et al. (2009) Donepezil delays progression to AD in MCI subjects with depressive symptoms. Neurology 72:2115-21