Dementia is the loss of mental abilities severe enough to interfere with your daily life. The symptoms include language difficulty, loss of recent memory and poor judgment. It generally takes hold after age 80.

Alzheimer’s disease (AD) accounts for 60% to 80% of dementia cases, and can strike as early as age 45. It is caused by progressive nerve damage to the brain that leads to memory loss, impaired thinking and verbal communication, as well as personality changes. A person who is suspected of having AD may live for 2 to 20 years with the condition. Alzheimer’s can only be diagnosed by autopsy after death.

Can we prevent AD? Short of effective medicines to come, scientists recommend we focus on related factors we have some control over: cardiovascular health, diabetes, obesity and exercise. Here are some recent findings:

Cardiovascular disease:

It has declined in the U.S. along with the rate of dementia since 1982, according to a 30-year Framingham Heart study. Primary reasons are better control of blood pressure and heart disease. Yet, even as heart failure and stroke dropped during this time, 2 risk factors for dementia have increased: diabetes and obesity.

BEST DEFENSE: Reduce your heart risks to also protect your brain.

Diabetes:

Studies show type 2 diabetes increases the rate of mental decline, based on memory test scores and likely due to elevated insulin levels. One theory is that the same enzyme needed to break down excess insulin (in type 2) can also degrade beta-amyloid, a protein related to AD brain damage.

BEST DEFENSE: Start watching your blood sugar to help prevent or control type 2 diabetes.

Obesity:

How can a big belly damage your brain? It may be the deep layer of visceral fat cells in the abdomen that’s at fault. This fat produces hormones that can raise insulin levels and diabetes risk. A 36-year study of 6,500 Kaiser Permanente members ages 40 to 45 found that people who were overweight and had large bellies were 2.3 times more likely to get dementia than those who had a normal weight and belly size.

BEST DEFENSE: Ask your health care provider for a healthy weight-loss program that trims your waist.

Exercise:

Staying physically active is good for mental health. New studies detail these effects on brain health, suggesting that vigorous exercise may be 1 of the most powerful protections against AD. Among older adults with increased genetic risk for Alzheimer’s, those who exercised regularly maintained normal healthy brains; when they began sitting too much, the positive effects began to reverse.

BEST DEFENSE: These results required at least 3 hours per week of strenuous physical activity, the kind that produces some sweating and heart pumping at 70% to 80% of your maximum heart rate.

Dementia is a widespread concern. Based on a survey of 2,700 people age 18-plus in the U.S. and Europe, Alzheimer’s is the most feared disease, after cancer, in their future. And with good reason when you know its far-reaching effects: Many years of dependence take a staggering emotional, physical and economic toll on families and health care. The prevalence of dementia is large and will rise sharply as baby boomers age.

By Diane McReynolds, Personal Best Healthlines Founder