Researchers are finding evidence that the type of personality you have may determine how likely you are to develop Alzheimer's disease.

A study of elderly people indicates that those who see themselves as self-disciplined, organized achievers have a lower risk than those who are less conscientious.

A co-author of the study says it could be that a purposeful personality can somehow protect the brain. Robert Wilson of Chicago's Rush University Medical Center says that type of personality could increase neural connections that act as a reserve against mental decline.

Some of the go-getters in the study were examined after their deaths. And they were found to have lesions that ordinarily would meet the accepted criteria for Alzheimer's. But they had shown no signs of dementia.

The findings appear in the Archives of General Psychiatry.