Exercise Slows Alzheimer's-like Brain Changes in Mice

Research demonstrated that long-term physical activity enhanced the learning ability of mice and decreased the level of plaque-forming beta-amyloid protein fragments - a hallmark characteristic of Alzheimer's disease (AD) - in their brains.29/04/2005

 
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In recent years, a number of population-based studies suggest that lifestyle interventions may help to slow the onset and progression of AD. Because of these studies, scientists are seeking to find out if and how physically or cognitively stimulating activity might delay the onset and progression of Alzheimer's disease.

To directly test the possibility that exercise, here in the form of voluntary running, may reduce the cognitive decline and brain pathology that characterizes AD, the study utilized a transgenic mouse model of AD rather than normal mice. These special mice begin to develop AD-like amyloid plaques at around 3 months of age. Initially, younger mice were placed in cages with or without running wheels for a certain period of time. Mice with access to running wheels had the opportunity to exercise any time, while those without the wheels were classified as "sedentary."

After the exercise phase, researchers placed each mouse in a Morris water maze to examine how fast it could learn the location of a hidden platform and how long it retained this information. The animals that exercised learned the task faster. Thus, the mice that used the running wheels took less time than the sedentary animals to find the escape platform. This suggests that exercise may help to offset learning/cognitive deficits present in AD patients.

Next, the investigators examined tissues from the brains of mice that had exercised. They compared the levels of plaques, beta-amyloid fragments, and amyloid precursor protein, a protein found throughout the body and from which the beta-amyloid peptide is derived. In AD, beta-amyloid fragments clump together to form plaques in the hippocampus and cerebral cortex, the brain regions used in memory, thinking, and decision making.

Compared to the sedentary animals, mice that had exercised had significantly fewer plaques and fewer beta-amyloid fragments in the cerebral cortex and hippocampus, approximately by 50 percent.

- More information on the NIH/National Institute on Aging at: www.nia.nih.gov

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