@article {1025, title = {Plasma amyloid levels and the risk of AD in normal subjects in the Cardiovascular Health Study.}, journal = {Neurology}, volume = {70}, year = {2008}, month = {2008 May 06}, pages = {1664-71}, abstract = {

OBJECTIVES: To examine the association between incident Alzheimer disease (AD), and plasma A beta 1-40 and A beta 1-42 levels in normal and mild cognitive impairment (MCI) subjects in a subgroup of participants of the Cardiovascular Health Study Cognition Study.

METHODS: We determined the plasma A beta 1-40 and A beta 1-42 levels of 274 nondemented subjects (232 normals and 42 with MCI) in 1998-1999 and repeated the measurements in 2002-2003. The mean age of the subjects at baseline was 79.3 +/- 3.6 years. We examined the association between A beta levels and incident AD over the ensuing 4.5 years, controlling for age, cystatin C level (marker of glomerular function), apolipoprotein E-4 allele, Modified-Mini-Mental State Examination scores, and MRI-identified infarcts.

RESULTS: In an unadjusted prospective model in normal subjects, both A beta 1-40 and A beta 1-42 levels in 1998-1999 were associated with incident AD (n = 55) in 2002-2003 (longitudinal analysis). In the fully adjusted multivariate model, neither A beta 1-42 nor A beta 1-40 nor their ratio was associated with incident AD. However, adjustment had a very small effect on point estimates for A beta 1-42, from an odds ratio (OR) of 1.61 (p = 0.007) in the unadjusted model to an OR of 1.46 (p = 0.08) in the fully adjusted model. In 2002-2003 (cross-sectional analysis), only the unadjusted models showed that both peptides were associated with AD.

CONCLUSIONS: Plasma A beta levels are affected by age and by systemic and CNS vascular risk factors. After controlling for these conditions, A beta-40 and A beta 1-42 are weak predictors of conversion to Alzheimer disease (AD) in normal subjects and are only weakly associated with AD in cross-sectional analysis. Consequently, plasma levels of A beta do not seem to be useful biomarkers for AD.

}, keywords = {Age Factors, Aged, Aged, 80 and over, Alzheimer Disease, Amyloid beta-Peptides, Apolipoprotein E4, Biomarkers, Brain, Cerebrovascular Disorders, Comorbidity, Cross-Sectional Studies, Cystatin C, Cystatins, Female, Humans, Incidence, Longitudinal Studies, Magnetic Resonance Imaging, Male, Models, Statistical, Neuropsychological Tests, Peptide Fragments, Predictive Value of Tests, Prospective Studies, Reference Values, Risk Factors}, issn = {1526-632X}, doi = {10.1212/01.wnl.0000306696.82017.66}, author = {Lopez, O L and Kuller, L H and Mehta, P D and Becker, J T and Gach, H M and Sweet, R A and Chang, Y F and Tracy, R and DeKosky, S T} } @article {1239, title = {Physical activity predicts gray matter volume in late adulthood: the Cardiovascular Health Study.}, journal = {Neurology}, volume = {75}, year = {2010}, month = {2010 Oct 19}, pages = {1415-22}, abstract = {

OBJECTIVES: Physical activity (PA) has been hypothesized to spare gray matter volume in late adulthood, but longitudinal data testing an association has been lacking. Here we tested whether PA would be associated with greater gray matter volume after a 9-year follow-up, a threshold could be identified for the amount of walking necessary to spare gray matter volume, and greater gray matter volume associated with PA would be associated with a reduced risk for cognitive impairment 13 years after the PA evaluation.

METHODS: In 299 adults (mean age 78 years) from the Cardiovascular Health Cognition Study, we examined the association between gray matter volume, PA, and cognitive impairment. Physical activity was quantified as the number of blocks walked over 1 week. High-resolution brain scans were acquired 9 years after the PA assessment on cognitively normal adults. White matter hyperintensities, ventricular grade, and other health variables at baseline were used as covariates. Clinical adjudication for cognitive impairment occurred 13 years after baseline.

RESULTS: Walking amounts ranged from 0 to 300 blocks (mean 56.3; SD 69.7). Greater PA predicted greater volumes of frontal, occipital, entorhinal, and hippocampal regions 9 years later. Walking 72 blocks was necessary to detect increased gray matter volume but walking more than 72 blocks did not spare additional volume. Greater gray matter volume with PA reduced the risk for cognitive impairment 2-fold.

CONCLUSION: Greater amounts of walking are associated with greater gray matter volume, which is in turn associated with a reduced risk of cognitive impairment.

}, keywords = {Aged, Aged, 80 and over, Brain, Brain Mapping, Cardiovascular Diseases, Cognition Disorders, Female, Humans, Longitudinal Studies, Magnetic Resonance Imaging, Male, Mental Status Schedule, Motor Activity, Neuropsychological Tests, Odds Ratio, Predictive Value of Tests, Surveys and Questionnaires}, issn = {1526-632X}, doi = {10.1212/WNL.0b013e3181f88359}, author = {Erickson, K I and Raji, C A and Lopez, O L and Becker, J T and Rosano, C and Newman, A B and Gach, H M and Thompson, P M and Ho, A J and Kuller, L H} }