A study involved 323 people who had no memory problems when first tested but later developed dementia. Memory tests and physical exams were then given every 18 months.

The study, published in the journal Neurology, found that after an Alzheimer's diagnosis was made, people with diabetes were twice as likely to die sooner than those without diabetes who had Alzheimer's disease. People with Alzheimer's disease who had high blood pressure were 2 1/2 times more like to die sooner than those with normal blood pressure.

"Studies show that the average lifespan of a person diagnosed with Alzheimer's can be anywhere from three to nine years. For that person and their caregiver, every minute counts," study author Yaakov Stern of Columbia University Medical Center in New York said in a statement.

"Here we have two controllable factors that may drastically affect how long that person can survive."