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【medical-news】新研究：早期海马区仅轻度萎缩的
"The summary of these results is that fitness is associated with hippocampal and parahippocampal volumes in early Alzheimer's disease patients but not in nondemented subjects," Robyn A. Honea, PhD, a postdoctoral fellow in the alzheimer's and memory program at the University of Kansas Medical Center, in Kansas City, told attendees here. "This suggests that maintaining cardiorespiratory fitness may modify Alzheimer's-disease-related atrophy."
The findings were presented here at ICAD 2008: Alzheimer's Association International Conference on Alzheimer's Disease.
Separate presentations reported that AD patients who did caregiver-directed exercise had a reduction in falls and an increase in quality-of-life measures.
Whole- and Regional-Brain Atrophy
The study by Dr. Honea and colleagues follows a paper published by their group in the July 15 issue of Neurology (2008;71:210-216), showing an association between cardiorespiratory fitness in early AD patients and whole-brain volume, after controlling for factors such as age, sex, and dementia severity; no such relation was seen in healthy elderly subjects without dementia.
In this follow-up investigation, the researchers looked at the association between cardiorespiratory fitness and regional-brain volumes using an MRI-based analysis technique called voxel-based morphometry.
A total of 63 early-stage AD patients and 56 nondemented subjects underwent MRI and treadmill testing to assess peak oxygen consumption (VO2 peak), a standard measure of cardiorespiratory fitness. MRI images were then processed and segmented into gray matter, white matter, and cerebrospinal fluid.
"Basically, what we're doing is trying to correlate a measure of aerobic fitness (VO2 peak) across the whole brain, on a voxel-by-voxel basis, to look for significant relations between that measure and smaller regional changes in gray- and white-matter volumes," Dr. Honea said.
They found that in patients with early AD, there was a significant relation between higher VO2 peak and higher hippocampal and parahippocampal volumes. These regions are associated with memory and, in the precentral gyrus, are associated with motor functions, "both of which we hypothesize might be related to cardiorespiratory fitness," she told Medscape Neurology & Neurosurgery. "But what was interesting is that it was just in the Alzheimer's group, and not in the nondemented group, that it was significant."
Dr. Honea pointed out that this is a cross-sectional study, which limits us from making recommendations about the effects of exercise in AD patients, but she noted that they are planning to begin a randomized trial of exercise in AD patients to look more closely at whether this relation is actually one of cause and effect. They also plan to follow this cohort to see if better cardiorespiratory fitness modifies the progression of AD over time.
During the discussion here, Dr. Honea was asked whether they plan to look at the number of white-matter lesions in these patients, where most of the changes were. She answered that they do plan to assess whether better cardiorespiratory fitness is associated with fewer white-matter lesions, using scans that are already available.
They will also be reporting on the effect of the apolipoprotein E genotype on the relation between cardiorespiratory fitness and atrophy in the brain.
Exercise Program for AD Patients
In 2 other studies presented here, researchers, led by Megan J Wraith, PhD, and R. Arthur Criddle, MD, both from Western Medicine, in Nedlands, Western Australia, found that a home-based exercise program for demented patients delivered by caregivers resulted in fewer falls and a better quality of life for both patients and their caregivers.
One third of older people living in the community fall each year, and those with dementia fall up to 3 times more than those who have no cognitive impairment, the authors note. In these studies, they assessed a caregiver-directed home-exercise program to see whether it would improve balance and reduce falls in people with dementia and whether it would affect the daily activities and quality of life of people with dementia.
A total of 33 pairs of patients and caregivers were randomized to an exercise program (n = 42) or usual care (n = 24). Caregivers in the exercise group were taught to guide the patients through a series of exercises at home.
Pairs in the exercise group were visited by investigators 8 times in the first 6 months of the study to ensure that exercises were being done correctly and safely. In the second 6 months, the caregivers were left to carry out the program independently, keeping track of exercise sessions, other physical activities, and falls on a daily basis. This information was submitted each month to investigators. Those in the usual-care group also received 8 home visits and also recorded falls and any physical activity.
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作者:admin@医学,生命科学 2011-06-02 17:14
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