A new study has found a dramatic rise in the number of cases of Alzheimer's disease and other forms of dementia in the United States over the past five years.

A report released by the Alzheimer's Association Tuesday, says more than five million Americans are now living with the degenerative brain disease. That is a 10 percent increase since the last such study, which was released five years ago.

The association says increasing age is the greatest risk factor for Alzheimer's, and that the prevalence of the disease will only rise at a similarly rapid rate as the general population ages.

The vast majority of those diagnosed with Alzheimer's are older than 65.

Early symptoms include confusion and memory loss. As the disease progresses and brain damage spreads, individuals need help with daily functions and eventually lose all ability to communicate. It is ultimately fatal.

Scientists have not yet determined a cause for the disease and related dementias, but Tuesday's report says there is increasing evidence that the health of the brain is linked to the health of the heart and blood vessels.

Some information for this report was provided by AP and Reuters.