How Your Body Mass Index (BMI) May Indicate Your Alzheimers Risk

A recent study suggests that if you're carrying a few extra pounds, you may significantly reduce your chances of developing Alzheimer's disease (AD) by working off those pounds and keeping them off.

And the key is your body mass index.

The new maths

You've probably heard of body mass index (BMI), but do you know what yours is?

BMI is calculated as weight in kilograms divided by the square of height in metres. But wait - don't let that scare you off. For those of us who are not metric savvy, there's another easy way to figure BMI. Just pull up a calculator and follow along:

First, figure your height in inches, then multiply that number by itself. So if you're 5' 5', for instance, you're 65 inches tall; 65 x 65 equals 4,225.

Next, divide your weight by that number. So if you weigh 150 pounds, divided by 4,225, that equals .0355.

Still with me? Now, one last step: Multiply that last number by 703. In the case of our example that equals 24.95, and that's your BMI. And if that really IS your BMI, then you're at the high end of the 'normal' zone.

A BMI of 18.5 to 24.9 is normal. Overweight is 25.0 to 29.9. And a BMI of 30.0 or above is considered obese.

These BMI ranges are used to determine relative risk for certain diseases such as type 2 diabetes. And according to recent research from Utah State University (USU), women who have BMIs in the obese range or the upper end of the overweight range may be at considerably higher risk of developing Alzheimer's disease as they age.

Men get a pass

Because previous trials have shown that vascular factors may contribute to Alzheimer's risk, and because obesity puts a strain on the vascular system, USU researchers wanted to examine the association between Alzheimer's disease (AD) and obesity.

Almost 400 subjects with no signs of dementia, aged 70 to 80, were followed for 18 years. During that time, neuropsychiatric tests were conducted and BMI was routinely measured.

At the end of the test period, researchers found there was no statistical correlation between BMI and Alzheimer's risk for men. In women, however, the association was significant. On average, women who developed dementia tended to have a BMI about two to three points higher than the women who remained mentally healthy.

The researchers concluded with this rule of thumb: At age 70, each 1.0 increase of BMI may raise Alzheimer's disease (AD) risk by 36 percent.

The results of this study are significant in light of the obesity crisis in Western countries. The Alzheimer's Association projects that by 2025 more than 22 million people worldwide may be diagnosed with Alzheimer's disease (AD). And if the USU research is correct, the current obesity trends will rise hand in hand with upward Alzheimer's disease (AD) trends.

Staying with the programme

Needless to say, regular exercise is essential to keep BMI in check. So it's probably no coincidence that exercise may also be an effective method of managing Alzheimer's symptoms for patients who have already been diagnosed with the disease.

Researchers at the University of Washington divided 153 Alzheimer's patients into two groups; one to receive 'routine' care, and the other to receive 30 minutes of light exercise each day in addition to routine care. Family caregivers for the latter group were also trained in behavioural management techniques to encourage the exercise regimen.

Two years later, researchers found that most of the patients in the exercise group remained physically active, experienced less depression than the 'routine care' group, and were in better physical shape with fewer indications of frailty.

The lead author of the UW study, Dr. Linda Teri, told the New York Times that the intervention significantly changed the patients' day-to-day functions. She said, 'They spend less time in bed and more time being active.'

This study didn't track changes in BMI, but I think it's safe to assume that following even a light exercise regimen over a two-year period will improve BMI. And once again we see how regular physical activity can improve the health of the mind as well as the body.