822 research outputs found
Diffusion Tensor Imaging Predictors of Episodic Memory Decline in Healthy Elders at Genetic Risk for Alzheimerās Disease
Objectives: White matter (WM) integrity within the mesial temporal lobe (MTL) is important for episodic memory (EM) functioning. The current study investigated the ability of diffusion tensor imaging (DTI) in MTL WM tracts to predict 3-year changes in EM performance in healthy elders at disproportionately higher genetic risk for Alzheimerās disease (AD). Methods: Fifty-one cognitively intact elders (52% with family history (FH) of dementia and 33% possessing an Apolipoprotein E Īµ4 allelle) were administered the Rey Auditory Verbal Learning Test (RAVLT) at study entry and at 3-year follow-up. DTI scanning, conducted at study entry, examined fractional anisotropy and mean, radial and axial diffusion within three MTL WM tracts: uncinate fasciculus (UNC), cingulate-hippocampal (CHG), and fornix-stria terminalis (FxS). Correlations were performed between residualized change scores computed from RAVLT trials 1ā5, immediate recall, and delayed recall scores and baseline DTI measures; MTL gray matter (GM) and WM volumes; demographics; and AD genetic and metabolic risk factors. Results: Higher MTL mean and axial diffusivity at baseline significantly predicted 3-year changes in EM, whereas baseline MTL GM and WM volumes, FH, and metabolic risk factors did not. Both Īµ4 status and DTI correlated with change in immediate recall. Conclusions: Longitudinal EM changes in cognitively intact, healthy elders can be predicted by disruption of the MTL WM microstructure. These results are derived from a sample with a disproportionately higher genetic risk for AD, suggesting that the observed WM disruption in MTL pathways may be related to early neuropathological changes associated with the preclinical stage of AD. (JINS, 2016, 22, 1005ā1015
Interactive Effects of Physical Activity and APOE-Īµ4 On White Matter Tract Diffusivity in Healthy Elders
Older adult apolipoprotein-E epsilon 4 (APOE-Īµ4) allele carriers vary considerably in the expression of clinical symptoms of Alzheimer\u27s disease (AD), suggesting that lifestyle or other factors may offer protection from AD-related neurodegeneration. We recently reported that physically active APOE-Īµ4 allele carriers exhibit a stable cognitive trajectory and protection from hippocampal atrophy over 18 months compared to sedentary Īµ4 allele carriers. The aim of this study was to examine the interactions between genetic risk for AD and physical activity (PA) on white matter (WM) tract integrity, using diffusion tensor imaging (DTI) MRI, in this cohort of healthy older adults (ages of 65 to 89). Four groups were compared based on the presence or absence of an APOE-Īµ4 allele (High Risk; Low Risk) and self-reported frequency and intensity of leisure time physical activity (PA) (High PA; Low PA). As predicted, greater levels of PA were associated with greater fractional anisotropy (FA) and lower radial diffusivity in healthy older adults who did not possess the APOE-Īµ4 allele. However, the effects of PA were reversed in older adults who were at increased genetic risk for AD, resulting in significant interactions between PA and genetic risk in several WM tracts. In the High Risk-Low PA participants, who had exhibited episodic memory decline over the previous 18-months, radial diffusivity was lower and fractional anisotropy was higher, compared to the High Risk-High PA participants. In WM tracts that subserve learning and memory processes, radial diffusivity (DR) was negatively correlated with episodic memory performance in physically inactive APOE-Īµ4 carriers, whereas DR was positively correlated with episodic memory performance in physically active APOE-Īµ4 carriers and the two Low Risk groups. The common model of demyelination-induced increase in radial diffusivity cannot directly explain these results. Rather, we hypothesize that PA may protect APOE-Īµ4 allele carriers from selective neurodegeneration of individual fiber populations at locations of crossing fibers within projection and association WM fiber tracts
Employment and Disability Policy: the role of the psychologist
Persons with minor or major disabilities represent a significant portion of the U.S. working-age population. Based on the 1993 Survey of Income and Program Participation (SIPP), approximately 30 million (19%) men and women 18 to 64 years of age report some type of physical or mental limitation. For approximately 55% of these individuals (about 10% of those 18 to 64), the limitations are severe
Interactive Effects of Physical Activity and APOE-Īµ4 on BOLD Semantic Memory Activation in Healthy Elders
Evidence suggests that physical activity (PA) is associated with the maintenance of cognitive function across the lifespan. In contrast, the apolipoproteinE-Īµ4 (APOE-Īµ4) allele, a genetic risk factor for Alzheimer\u27s disease (AD), is associated with impaired cognitive function. The objective of this study was to examine the interactive effects of PA and APOE-Īµ4 on brain activation during memory processing in older (ages 65ā85) cognitively intact adults. A cross-sectional design was used with four groups (n = 17 each): (1) Low Risk/Low PA; (2) Low Risk/High PA; (3) High Risk/Low PA; and (4) High Risk/High PA. PA level was based on self-reported frequency and intensity. AD risk was based on presence or absence of an APOE-Īµ4 allele. Brain activation was measured using event-related functional magnetic resonance imaging (fMRI) while participants performed a famous name discrimination task. Brain activation subserving semantic memory processing occurred in 15 functional regions of interest. High PA and High Risk were associated with signiļ¬cantly greater semantic memory activation (famous\u3eunfamiliar) in 6 and 3 of the 15 regions, respectively. Signiļ¬cant interactions of PA and Risk were evident in 9 of 15 brain regions, with the High PA/High Risk group demonstrating greater semantic memory activation than the remaining three groups. These ļ¬ndings suggest that PA selectively increases memory-related brain activation in cognitively intact but genetically at-risk elders. Longitudinal studies are required to determine whether increased semantic memory processing in physically active at-risk individuals is protective against future cognitive decline
FreeSurfer vs. Manual Tracing: Distinguishing Stable from Cognitively Declining Elders Using Prospectively Measured Hippocampal Volume
Objective: Alzheimerās disease (AD) pathology is thought to begin years before symptom onset. Hippocampal volume is sensitive to age-related cognitive decline and conversion from MCI to AD. Measurement of hippocampal volumes has used either automated methods such as FreeSurfer (FS) or manual tracing (MT). We compared the ability of FS and MT in detecting baseline volume differences in cognitively intact older individuals who subsequently showed significant cognitive decline.
Participants and Methods: Seventy-five cognitively intact elders underwent baseline and 18-month follow-up structural MRI scan and neuropsychological testing. Participants were classified as Declining (n=27) or Stable (n=48) based on the baseline to 18-month changes on a listlearning task and a measure of general cognitive functioning. A 2 (left, right) x 2 (anterior, posterior) x 2 (Declining, Stable) repeated measures ANOVA was conducted for both the MT and FS hippocampal volumes derived at baseline.
Results: MT identified significantly smaller left and right hippocampal volumes and smaller anterior than posterior hippocampal volumes in Declining compared to Stable subjects. In contrast, no group differences in hippocampal volumes were observed using FS. Notably, MT included more subiculum and entorhinal cortex, while FS included more of the amygdala and the CA region of the hippocampus.
Conclusions: MT was superior to FS for detecting prospective volumetric differences associated with cognitive decline in cognitively intact older participants. MT afforded more unique coverage of the anterior hippocampus than FS. The differences in regional coverage of the mesial temporal lobe between MT and FS may account for the different findings in discriminating Stable and Declining groups
Five-Year Changes in Brain Volume and Episodic Memory in Cognitively Intact Elders with and without an Apolipoprotein Īµ4 Allele
The apolipoprotein Īµ4 allele is a risk factor for Alzheimer\u27s disease. Īµ4 carriers diagnosed with AD or MCI exhibit an increased rate of atrophy on MRI relative to non-carriers. Few longitudinal studies have examined the rate of atrophy and cognitive change in older Īµ4 carriers who were cognitively intact at study entry. In this study, structural MRI and episodic memory testing were administered on two occasions separated by 5 years to 45 cognitively intact older adults, ages 65-90 years, divided into two groups: (1) carriers with one or both Īµ4 alleles (n=24) and (2) demographically-matched non-carriers (n=21). Longitudinal analysis of whole brain gray matter, whole brain white matter, and hippocampal volumes were derived from Freesurfer software. Analysis of variance indicated a significant group x time interaction for both left and right cortical gray matter (p\u27s \u3c .05; 2% decrease) and left hippocampus (p \u3c .001; 5.6% decrease); right hippocampus showed a marginal effect (p=.086; 4.9% decrease). In all instances, the Īµ4 group showed greater atrophy over the five-year interval than non-carriers. White matter brain volume significantly decreased over retest intervals (3.5%), but did not differ between groups. Over the same retest interval, the Īµ4 group also showed significantly greater decline than non-carriers on delayed word recall and percent retention on a list-learning task. These data suggest that the presence of an Īµ4 allele carries an increased risk for cortical gray matter and hippocampal atrophy and memory loss among older participants who were cognitively intact at study entry
Prediction of Longitudinal White Matter Change in Healthy Elderly Individuals
Diffusion Tensor Imaging (DTI) studies have shown that significant alteration in white matter (WM) integrity differentiates healthy older adults from persons with Mild Cognitive Impairment (MCI) and Alzheimer\u27s disease (AD). Most studies, however, have been cross-sectional and have not related longitudinal DTI changes to cognitive change. Here we report changes in WM integrity and cognition in healthy older adults over an 18-month interval. Sixty-seven cognitively intact elders underwent neuropsychological testing and DTI at baseline to follow-up on the Rey Auditory Verbal Learning Test (recall sum across trials 1-5, delayed recall) and Mattis Dementia Rating Scale-2. Declining participants (N=21) showed a minimum of 1 SD reduction on at least one cognitive measure, while Stable participants (N=46) showed comparable scores at each time point. WM regions-of-interest were derived from Freesurfer. Hierarchical linear regression was used to predict fractional anisotropy (FA) change in regions frequently identified in DTI studies of MCI and AD including transentorhinal cortex, temporal lobe, and posterior cingulate. Groups did not differ at baseline in age, cognition, FA, or WM volume. After controlling for age and baseline FA, cognitive status (Declining, Stable) predicted the baseline to 18-month reduction in FA in the right hippocampal gyrus (p=.004) and left fusi-form gyrus (p=.01) with a trend in the left middle temporal gyrus (p=.06). Future research should examine WM changes in other brain regions and determine whether DTI diffusivity measures are related to cognitive decline
Lifestyle and Genetic Contributions to Cognitive Decline and Hippocampal Structure and Function in Healthy Aging
Background: Engagement in cognitively stimulating activities (CA) and leisure time physical activity (PA) have been associated with maintaining cognitive performance and reducing the likelihood of cognitive decline in older adults. However, neural mechanisms underlying protective effects of these lifestyle behaviors are largely unknown. In the current study, we investigated the effect of self-reported PA and CA on hippocampal volume and semantic processing activation during a fame discrimination task, as measured by functional magnetic resonance imaging (fMRI). We also examined whether possession of the apolipoprotein E (APOE) ?4 allele could moderate the effect of PA or CA on hippocampal structure or function. Methods: Seventy-eight healthy, cognitively intact older adults underwent baseline neuropsychological assessment, hippocampal volume measurement via manually-traced structural MRI, and task-activated fMRI. Results: After 18 months, 27 participants declined by one standard deviation or more on follow-up neuropsychological testing. Logistic regression analyses revealed that CA alone or in combination with baseline hippocampal structure or functional activity did not predict the probability of cognitive decline. In contrast, PA interacted with APOE 4 status such that engagement in PA reduced the risk of cognitive decline in APOE 4 carriers only. Furthermore, the benefits of PA appeared to diminish with reduced functional activity or volume in the hippocampus. Conclusions: Our findings suggest that increased leisure time PA is associated with reduced probability of cognitive decline in persons who are at high risk for AD. The beneficial effects of PA in this group may be related to enhancement of the functional and structural integrity of the hippocampus
Longitudinal Associations between Physical Activity, Cognitive Status, and Brain Function in Older Adults at Genetic Risk for Alzheimerās Disease
The apolipoproteinE epsilon4 (APOE-?4) allele is associated with cognitive decline in old age and is a risk factor for Alzheimer\u27s disease (AD). Physical activity (P A) is associated with a reduced risk of incident cognitive impairment, particularly among APOE-?4 carriers. We recently reported greater semantic memory related brain activation in cognitively intact physically active (High P A) APOE-?4 carriers compared to physically inactive (Low PA) ?4 carriers and non-carriers (Smith et al., 2011). Here, we compared longitudinal changes in semantic memory-related brain activation in High PA and Low PA APOE-?4 carriers. Thirty-two older ?4 carriers completed neuropsychological testing and a fMRI semantic memory task (famous name discrimination) at baseline and after 18 months. All participants were cognitively intact at baseline and were classified as High PA (n = 16) or Low PA (n = 16) based on self-report. After 18 months, 5 of 16 High P A and 13 of 16 Low P A were classified as cognitively declining by at least 1 SD decrease in neurocognitive performance (Group difference, p = .011, Fisher\u27s exact test). A fROI analysis of the fMRI data and repeated measures ANOV As revealed significant Group by Time interactions for intensity of semantic memory-related activation. Significantly greater activation at baseline in the High PA group was attenuated over time (no change in Low P A) and resulted in no group differences at the 18-month follow-up. These findings suggest that greater P A at baseline is associated with greater cognitive stability over 18-months in APOE-?4 carriers and reduced neural activation during fame discrimination
Reviews
The following publications have been reviewed by the mentioned authors;Beginning Graphical Communication by M. Jordan, B. Hawtin and A. Neil, reviewed by John LeesArt Related Topics by Bob Nunn and Chris Locke, reviewed by A. CharltonHandbook for Art and Design Students by Robin Jesson, reviewed by John LancasterDrawing and Cognition Descriptive and Experimental Studies of Graphic Production Processes by Peter Van Sommers, reviewed by Pamela M. SchenkThe Student's Guide to Western Calligraphy an Illustrated Survey by Joyce Irene Whalley, reviewed by John LancasterSource Directory for Authentic Indian, Eskimo and Aleut Arts and Crafts by the Indian Arts and Crafts BoardMarianne Straub by Mary Schoeser, reviewed by Kim GreerMisha Black by Avril Blake, reviewed by Kim Greer'Working inĀ Crafts' - A National Survey by the Crafts Council, reviewed by L. SayerDirectory of Design Expertise by the Design Council, reviewed by R. Smit
- ā¦