As the Baby Boomers in their 40s and 50s start looking to the future, they worry whether their own aging will bring one of its most feared consequences - mental decline.

From Harvard health experts, here are nine ways to keep your mind sharp as the golden years approach:

1. Get mental stimulation. Read, draw, take classes, and explore new hobbies. Brainy activities stimulate new connections between nerve cells and may even help the brain generate new cells.

2. Get physical exercise. Exercise increases the number of blood vessels that bring blood to the region of the brain responsible for thought. It also spurs the development of new nerve cells. In one study, for every mile a woman walked each day, her risk of cognitive decline dropped by 13 percent.

3. Improve your diet. Cut the calories. Also remember your Bs: folic acid and vitamins B6 and B12 help lower levels of homocysteine, an artery-damaging amino acid, and cut the risk of dementia.

4. Improve your blood pressure. High blood pressure in midlife increases the risk of mental fuzziness.

5. Improve your cholesterol. High LDL "bad" cholesterol increases the risk of dementia, as do low levels of HDL "good" cholesterol.

6. Avoid tobacco.  According to one study, smoking doubles the risk of losing mental sharpness.

7. Don't abuse alcohol. Excessive drinking is a major risk factor for dementia. If you drink alcohol, limit yourself to two drinks per day.

8. Protect your head. Moderate to severe head injuries early in life increase the risk of an unhealthy brain.

9. Build social networks. One study linked frequent social interactions with a 42 percent reduction in the risk for dementia.