Exercise may promote healthy communication between blood vessels and brain cells.
Blood-brain communication. I’m Bob Hirshon and this is Science Update.
Alzheimer’s disease is a disease of the brain, but the cardiovascular system also plays a role: active people are less likely to develop Alzheimer’s than are sedentary people. Genomic scientist Gareth Howell at The Jackson Laboratory says there’s an important connection between our brain’s blood vessels and its neurons.
This is a critical communication that makes the nerve cells work to their maximum capacity. And if you don’t have a good communication with the blood vessels, that’s going to decline.
This communication begins to falter with aging, worsens with a poor diet, and can accelerate the onset of Alzheimer’s disease. But Howell and his colleagues report that in laboratory mice, exercise was remarkably effective at maintaining communication between blood vessels and brain cells, reducing Alzheimer’s progression. I’m Bob Hirshon, for AAAS, the science society.
Making Sense of the Research
When it comes to many diseases, like cancer, diabetes, and Alzheimer's, people often wonder what they can do to prevent being afflicted. It often seems that, even when someone appears to be fit and healthy, that person still can be diagnosed with a serious disease. While we may not be able to predict who will or who won't get a critical illness, there are things that individuals can do to lessen their risk of getting them.
Research being conducted by genomic scientist Gareth Howell and others seems to indicate that exercise can have a positive effect on overall chances of developing Alzheirmer's Disease (AD). That is, when one looks at a population of people, those who are active tend to be less likely to get the disease. Howell and his fellow scientists are studying how exercise can have this positive effect on AD.
To do this research, Howell and his colleagues have been studying exercise and diet and AD as well as gene variants associated with the disease. One gene they have been focusing on is the ApoE gene, which codes for apolipoprotein E, a protein produced in the liver that packages cholesterol and other fats and carries them through the bloodstream. ApoE is also produced by the cells that form the blood-brain barrier and provide nutrients to neural cells, including the delivery of cholesterol to neurons. (The blood-brain barrier prevents some substances in the blood from entering the brain.)
The researchers have been using mice to carry out their experiments. To determine gene expression changes in response to normal aging, they studied the brain tissue of young and old mice. So far, their research has found that mice with the ApoE gene knocked out develop extremely high cholesterol levels when fed a high-fat diet, and they don’t reap the neurovascular benefits of exercise.
At least as far as mice are concerned, the presence of ApoE, combined with diet and exercise, seems to provide some benefits to mice in preventing AD. And this study meshes with other findings linking blood-brain barrier damage with age and cognitive decline in people. More research needs to be done, however, before exactly what role ApoE plays in human AD can be determined.
Now try and answer these questions:
- According to Gareth Howell, what effect does exercise have on a person's chances of developing Alzheimer's disease?
- What is the blood-brain barrier?
- What is ApoE? Why is it important in the study of Alzheimer's?
- How did the scientists carry out their research?
- How might this research be extended and applied to humans?
You can listen to Word Associations to learn more about how researchers are studying exactly what happens in the brain when it learns and remembers information.
You can visit Alzheimer's Association: Kids & Teens site to get more information about the disease.
You can help your students extend their learning in this Science Update by having them listen to Brain Sniff Test, which looks at how a simple sniff test may help doctors pick up the scent of debilitating brain diseases.
The Alzheimer's Disease Fact Sheet, from the National Institute on Aging, provides good background information about the disease.
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