Doctors say exercise can help slow early onset of the disease.
Susan Harvell was diagnosed with Alzheimer's at the age of 53.
Harvell describes herself as a type A go-getter, a Human Resources executive in Silicon Valley who is always active.
Recently her husband noticed some changes in her.
"She would ask questions repeatedly," Dave Baker said.
After a series of brain scans and memory tests at Stanford Hospital and Clinics Center for Memory Disorders, Harvell was diagnosed with Alzheimer's disease.
She can no longer work or drive.
"I cried on the way home" said Harvell, who lives in San Jose. "It was turning my life upside down."
"It is a difficult diagnosis that things are not going to get better, we were both in shock quite awhile," Baker said.
Of the 5.4 million Americans living with Alzheimer's, the Alzheimer's association estimated that 400,000 people were diagnosed before age 65, and the number is growing.
Harvell's doctor, Stanford behavioral neurologist Dr. Geoffrey Kerchner, said however difficult, an early diagnosis can offer patients an advantage.
"The useful aspects of the medications can help treat symptoms of memory today, these are benefits encountered in earlier stages of the illness," Kerchner said.
He says current medications will not slow the progression of the disease, but something simple might.
"The one thing we've identified so far that does seem to slow down the disease process is aerobic exercise. As old fashioned as it sounds it is more effective than any medication that's been invented," Kerchner said.
Harvell has always loved to walk, so this prescription isn't a hard one for her to swallow.
He also said research indicates exercise may also be able to help delay the age you develop the disease if you're at risk.
As she shares memories with her daughter Claire, Harvell said she considers her early diagnosis a gift.
"I have more time to make decisions about how I want to do things," she said.
She also wants to make a difference by volunteering for the Alzheimer's Association to raise money for research and participating in a clinical trial at Stanford to test a new Alzheimer's drug.
She wants to do what she can to make sure
Future patients will have more options.
"I have to take things day by day, I feel great now," Harvell said. "I feel I can do anything."