Developing dementia is a common fear, especially for those who have seen a loved one go through the agonizing and progressive mental decline that Alzheimer's brings. We all want to maintain great memory, mental clarity and brain power throughout our life. Given that, here are three studies on Alzheimer's recently in the news:

High cholesterol in your 40's may increase your risk of developing Alzheimer's. A study researching the link between middle-age cholesterol and Alzheimer's risk looked at more than 9,000 people in northern California. It found that those with high cholesterol levels between ages 40 and 45 were about 50 percent more likely to develop Alzheimer's disease decades later.

This study highlights why prevention is so important - and that it is never too early to start thinking about making lifestyle changes. Forty-year-olds with elevated cholesterol may not feel that it is terribly important to decrease their cholesterol - especially if they are in otherwise good health. But the young age of 40 may be exactly the time to start preventing Alzheimer's disease.

Exercising in your 50s and 60s can reduce the risk of Alzheimer's. Mayo researchers looked at more than 800 people as part of the Mayo Clinic Study of Aging. They found that moderate physical exercise between the ages of 50 and 65 was associated with a reduced risk of cognitive impairment.

It is unknown why exercise seems to help prevent dementia. It could be due to certain chemicals released into the brain during exercise or other healthy effects of exercise on the body such as decreased fat and increased muscle mass. It can also be because those who exercise are also likely to have an overall healthy lifestyle. We think that this is a good enough reason for couch potatoes in their 50's to embrace a lifestyle change. You can start by enjoying the beautiful spring weather in a daily walk, 30 minutes a day five days a week.

Big bellies lead to an increased risk of Alzheimer's. A study by the Kaiser Permanente Division of Research involving more than 6,000 people was published in the Journal of Neurology. It found that the more belly fat people had in their early to mid-40s, the greater their chances of developing cognitive impairment. How big is big? Interestingly enough, for all weight ranges from normal to morbidly obese, those who carried their weight around their midsection had a significantly higher risk of dementia. The dementia risk increased as weight increased. Those with a belly of more than 39 inches had the greatest risk of developing dementia.

So what does the average person make of this? Getting into good health in your middle adulthood years can make a big change in how healthy you are in later years. If you are in your 40's or older, and have high cholesterol, are sedentary, and/or have a large belly, consider changing these risk factors. If you have not had your cholesterol checked, do so at your next doctor's visit. Working on your lifestyle now may be a valuable investment in your future brain health.

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(Drs. Kay Judge and Maxine Barish-Wreden are medical directors of Sutter Downtown Integrative Medicine program in Sacramento, Calif. Have a question related to alternative medicine? E-mail adrenaline@sacbee.com.)