A recently published study reported that body mass index (BMI) was independently associated with memory and changes in word-list learning in healthy middle-aged men and women. BMI is a measure of body fat based on height and weight that applies to both men and women. BMI is calculated in US units by dividing weight in pounds by height in inches squared. BMI is used to determine if a person is normal, underweight, overweight or obese. BMI ranges are normal 18.5 - 24.9, underweight below 18.5, overweight 25 - 29.9, and obese 30 and above. BMI is often used in the US to determine the risk of diabetes. Diabetes has been linked to a 65% higher risk of Alzheimer's disease. There are a few proposed mechanisms how diabetes may contribute to Alzheimer's disease. High blood sugar causes damage to blood vessels. Although vascular dementia is different than Alzheimer's, researchers believe blood vessel dementia may accelerate changes that contribute to Alzheimer's disease. A second possible mechanism involves insulin in the brain. As type 2 diabetes develops, insulin resistance develops, requiring that larger amounts are produced by the pancreas. The brain protects itself from high insulin levels by not allowing insulin to cross the blood brain barrier. The result is lower insulin levels in the brain, starving brain cells of glucose. Third, high levels of insulin in the blood stream may trigger the production of beta-amyloid, a protein responsible for plaque formation on brain cells associated with Alzheimer's disease.

Dementia is also associated with every risk factor for heart disease including smoking, overweight, abdominal obesity, and diabetes. Another study tested 460 subjects of the Scottish Mental Survey who were given general memory tests in 1932 at age 11 and again at age 79. They were also tested for physical fitness at age 79. Those who had the highest scores for physical fitness also had the highest scores for mental function. These results add evidence that physical exercise helps to protect your brain from dementia.

Studies have shown that physical exercise improves blood flow to certain areas of the brain associated with memory and learning. Animal studies have even shown the growth of new brain cells associated with physical exercise. It is this increased blood flow to the brain that is thought to be responsible for maintaining mental function. A healthy diet is also associated with reduced risk of Alzheimer's disease. Study results are best for those who do both, exercise regularly and eat a healthy diet. Regular exercise and a healthy diet are also keys to maintaining a normal BMI.

The benefits of a healthy lifestyle seem to include maintaining mental health as well as physical health. A healthy lifestyle includes daily exercise, a diet low in saturated and trans fats and rich in fruits and vegetables, no smoking, regular relaxation, and adequate sleep.

Reference: http://drmirkin.blogspot.com/2007/02/prevent-memory-loss-with-exercise.html, http://www.mayoclinic.com/health/diabetes-and-alzheimers/AZ00050, http://alzheimers.about.com/cs/research/a/diabetes_risk.htm.

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