U.S. researchers have developed a checklist that can accurately predict whether a person over 65 is at high risk of developing Alzheimer's disease within six years.

The checklist of risk factors like slowness of mind or movement predicted about half the cases of dementia that developed in a group of elderly people over a six year period, the researchers reported in the journal Neurology on Wednesday.

An estimated 26 million people globally have Alzheimer's disease, the most common form of dementia. The disease starts out with mild memory loss and confusion but escalates into complete memory loss and an inability to care for oneself.

Researcher Deborah Barnes of the University of California, San Francisco, said having a tool that can predict the risk of developing Alzheimer's could help doctors keep an eye on patients and help companies develop drugs to treat the early stages of the mind-robbing disease, which has no cure and few effective treatments.

"This new risk index could be very important both for research and for people at risk of developing dementia and their families," Barnes said in a statement.

The tool consists of a 15-point scale of several well-known risk factors for Alzheimer's — advanced age, low scores on tests of thinking skills, and having the ApoE4 gene, which raises the genetic risks of developing it.

It also includes some lesser-known risk factors, such as being underweight, having a history of heart bypass surgery, not drinking alcohol or being slow to do physical tasks like buttoning a shirt.

People with a score of 8 or higher are considered at high risk of developing dementia within the next six years.

To develop the index, the team studied 3,375 people with an average age of 76 and no evidence of dementia. Over six years, 480 of the people developed dementia.

The researchers then looked to see which factors best predicted who would develop dementia.

When they evaluated the same group using the checklist, they found 56 percent of those with high scores had developed dementia within six years. That compared to 23 percent with moderate scores and just four percent with low scores.

Overall, the index correctly classified 88 percent of the participants.

Barnes said the risk index will need to be confirmed by other studies. Her team is also looking to see if a simpler version could be as accurate.