Alzheimer's now affects some 5.4 million Americans; and it is a disease for which there is not only no cure, but no meaningful treatment. That said, it's fundamentally important to embrace the notion that Alzheimer's is a preventable disease.

If you live to be age 85 years, or have already reached that milestone, statistically your risk for Alzheimer's is a breathtaking 50/50. That's a flip of a coin.

The good news is that recent scientific research is revealing that we can choose to change those odds for the better—dramatically!

Exercise is key to keeping your brain healthy

In upcoming articles, I'll be focusing on important dietary changes that can protect your brain, but for now I want to discuss the incredibly powerful role of aerobic exercise. While we all know that exercise makes for a healthier heart and may strengthen our bones, aerobics may well be the most powerful tonic for preserving, and even enhancing, brain health and function.

In a recent report in the prestigious scientific journal, "Proceedings of the National Academy of Science," researchers from the University of Pittsburgh described their results in comparing two groups of people. Each group of contained 60 similarly aged adults. One group was given a stretching program to perform each day, while the second group was given an aerobics program. At the beginning of the study, all participants had an MRI scan of their brains and a memory test. After one year, the MRI scans that were actually dedicated to evaluating the brain's memory center, as well as the memory test, were repeated in all the participants.

The results were astounding. The individuals who merely did the stretching showed progressive shrinking of their memory centers on the MRI scans, along with a decline in memory function. But, this was not observed in the group that did the aerobics. In fact, the MRI scans showed that there was an actual increase in the size of their memory centers, as well as improvement in memory function!

Lead researcher of the study, Dr. Kirk Erikson, stated in the conclusion of the report, "These results clearly indicate that aerobic exercise is neuroprotective and that starting an exercise regimen later in life is not futile for either enhancing cognition or augmenting brain volume."

If only there were a pill that we could take that could accomplish this! As of this writing, no pharmaceutical remedy for Alzheimer's disease exists. And Alzheimer's begins with both shrinkage of the brain's memory center, as well as progressive failure of memory function.

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So, the take home message is to dust off your sneakers and get back in the game. I recommend about 20 minutes of some form of aerobic exercise each day. Whether you choose to walk, bike, jog or swim, the key is to keep your heart rate up for the entire duration of your program.

As always, check with your healthcare provider before starting any new exercise program.