New research claims that moderate exercise is not only good for memory as people age, but also appears to help prevent the development of physical signs of Alzheimer’ in those who are at risk for the disease. “Our research shows that, in a late-middle-age population at risk for Alzheimer’s disease, physically active individuals experience fewer age-related alterations in biomarkers associated with the disease, as well as memory and cognitive functioning,” says Ozioma Okonkwo, Ph.D., an assistant professor of medicine at the University of Wisconsin School of Medicine and Public Health. The findings were presented from multiple studies at the recent American Psychological Association convention. Researchers examined 317 participants enrolled in the Wisconsin Registry for Alzheimer’s Prevention, an ongoing observational study of more than 1,500 people with a history of parents with probable Alzheimer’s dementia.
The researchers compared data from individuals younger than 60 years with older adults and found a decrease in cognitive abilities as well as an increase in biomarkers associated with the disease in the older individuals. However, the effects were significantly weaker in older adults who reported engaging in the equivalent of at least 30 minutes of moderate exercise five days a week. “The most interesting part of our research is that we now show evidence that lifestyle habits – in this case regular, moderate exercise – can modify the effect of what is commonly considered a non-modifiable risk factor for Alzheimer’s, in this case aging,” Okonkwo continued.
Researchers also studied 95 people from the registry who were given scores called polygenic risk scores, based on whether they possessed certain genes associated with Alzheimer’s. They looked at how biomarkers changed with genetic risk and what role, if any, aerobic fitness might play. People with higher risk scores also showed increased biomarkers for the disease. They found that the effect was weaker in people with greater aerobic fitness, a score incorporating age, sex, body mass index, resting heart rate and self-reported physical activity.
They also examined MRIs from 107 individuals from the registry who were asked to run on a treadmill to determine their oxygen uptake efficiency slope, a measure of aerobic fitness. Again they found an indicator of the Alzheimer’s - white matter hyperintensities - significantly increased in the brain with age, but not so much in participants with high levels of aerobic fitness. “Overall, these studies suggest that the negative effect of aging and genetic risk on Alzheimer’s’ disease biomarkers and cognition can be lessened in physically active, older adults at risk for the disease compared with their less active peers,” Okonkwo added. “If these findings are supported by more prospective, controlled studies, it would provide compelling evidence for physical activity as an effective approach to prevention, particularly in at-risk populations.”
Exercise And Long-Lasting Benefits
Researchers from the Liggins Institute at the University of Auckland discovered that bone retains a "memory" of exercise's effects long after the exercise is ceased. They say this bone memory continues to change the way the body metabolizes a high-fat diet. The research - in Frontiers in Physiology - compared the bone health and metabolism of rats across different diet and exercise conditions, zeroing in on messenger molecules that signal the activity of genes in bone marrow. Rats were either given a high-fat diet and a wheel for extra exercise in their cage, a high-fat diet but no wheel, or a regular diet and no wheel. In the rats given a high-fat diet and an exercise wheel, the early extra physical activity caused inflammation-linked genes to be turned down.
Inflammation is the body's natural self-protective response to acute infection or injury, but the ongoing, low-grade inflammation linked to high-fat diets can harm cells and tissues and raise the risk of obesity, heart disease, cancer and other diseases. High-fat diets early in life are known to turn up, or increase the activity of other genes that cause inflammation. Exercise also altered the way the rats' bones metabolized energy from food, changing energy pathways that disrupt the body's response to a high-calorie diet. "What was remarkable was that these changes lasted long after the rats stopped doing that extra exercise into their mid-life," says molecular geneticist Dr. Justin O'Sullivan. "The bone marrow carried a 'memory' of the effects of exercise. This is the first demonstration of a long-lasting effect of exercise past puberty. The rats still got fat, but that early extra exercise basically set them up so that even though they put on weight they didn't have the same profile of negative effects that is common with a high-fat diet."
This may help scientists understand why, even though obesity and diabetes are often linked, some people with obesity do not develop diabetes. "It also strongly emphasizes the health benefits of exercise for children," O'Sullivan added. “With rising rates of overweight and obesity in children, it is important to understand the effects of these conditions on bone health,” added Professor Mark Vickers. "Obesity is governed by many genes. This work highlights the utility of small animal models in teasing out gene-environment interactions in health and disease."
Childhood and adolescence are periods of rapid bone growth, added Professor Elwyn Firth. "If you reach optimal bone mass early in life, you're less likely to suffer from broken bones or other bone-related problems as an adult. Load-bearing from exercise and higher bodyweight is good for growing bones, but this and other evidence shows that if the extra weight comes from higher body fat mass, bone development may be subnormal. Bone metabolism strongly influences energy metabolism in the body, and metabolism - what you do with energy from diet - is the central crux of why some children and adults become obese."
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