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.

Purpose To examine regional cerebral blood flow (rCBF) in incident mild cognitive impairment (MCI) and Alzheimer disease (AD) by using continuous arterial spin-labeling (CASL) magnetic resonance (MR) imaging. Materials and Methods This study was approved by the local institutional review board and was compliant with HIPAA regulations. Informed consent was obtained. rCBF was measured in 38 control subjects, 29 MCI patients, and 37 AD patients who were participating in a longitudinal epidemiologic study. Multisection CASL MR imaging with alternating single and double adiabatic inversion pulses and ramp-sampled echo-planar imaging were performed to acquire 19 contiguous axial sections. Voxel-level rCBF was compared among groups by using an analysis of variance design; clusters of voxels with significant group differences were identified. Multiple regression models controlled for age, sex, and presence of hypertension and related the mean rCBF in those clusters to the presence of MCI and AD. Results MCI and AD patients had decreased rCBF in the posterior cingulate gyrus (P =.01) with extension to the medial precuneus compared with that in control subjects. MCI patients had increased rCBF in the left hippocampus (P <.001), right amygdala (P =.007), and rostral head of the right caudate nucleus and ventral putamen and globus pallidus (P =.003) compared with that in control subjects. AD patients had decreased rCBF relative to that in control subjects and MCI patients in the left inferior parietal (P =.005), left lateral frontal (P <.001), left superior temporal (P =.001), and left orbitofrontal (P =.003) cortices. AD patients had increased rCBF in the right anterior cingulate gyrus (P =.02) compared with that in control subjects. Conclusion The transition from normal cognition to AD is associated with dynamic pathologic processes in the brain, and this is reflected by both decreases and increases in rCBF. Increases in rCBF suggest a cellular and vascular compensatory process associated with incipient AD.

Objectives This study aimed at developing technical recommendations for the acquisition, processing and analysis of renal ASL data in the human kidney at 1.5 T and 3 T field strengths that can promote standardization of renal perfusion measurements and facilitate the comparability of results across scanners and in multi-centre clinical studies. Methods An international panel of 23 renal ASL experts followed a modified Delphi process, including on-line surveys and two in-person meetings, to formulate a series of consensus statements regarding patient preparation, hardware, acquisition protocol, analysis steps and data reporting. Results Fifty-nine statements achieved consensus, while agreement could not be reached on two statements related to patient preparation. As a default protocol, the panel recommends pseudo-continuous (PCASL) or flow-sensitive alternating inversion recovery (FAIR) labelling with a single-slice spin-echo EPI readout with background suppression and a simple but robust quantification model. Discussion This approach is considered robust and reproducible and can provide renal perfusion images of adequate quality and SNR for most applications. If extended kidney coverage is desirable, a 2D multislice readout is recommended. These recommendations are based on current available evidence and expert opinion. Nonetheless they are expected to be updated as more data become available, since the renal ASL literature is rapidly expanding.

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.