"I remember saying to my sister, 'Are we going to get it? Is Mom?' " says Daisy, now 39, who lives in Springfield, Missouri.
But it wasn't until after her mother, Sonia Cardona, now 59, tested positive for one of the three genes that causes early-onset familial Alzheimer's that she found out how prevalent it really was.
In August 2013, one of her mom's sisters came from Puerto Rico to lay out their family history to Dr. Beau Ances, her mother's neurologist at the Washington University School of Medicine in St. Louis.
"I didn't know how bad it was until then – how many people in our whole family," she tells PEOPLE. "We knew it was bad in our family, but we didn't know it was that bad. It was like, 'Okay. It's the luck of the draw. Some have it, some don't.'
"But as my aunt kept talking, I'm like, 'Oh my God! Everybody's died from Alzheimer's on my mother's side,' " says Duarte who has been caring for her mother full time for nearly four years.
"I cried," she says.
She also made a gut-wrenching decision: to enroll in the Dominantly Inherited Alzheimer Network, an observational study spearheaded by the Washington University School of Medicine, and get tested to find out if she carries one of the genes herself.
"Seventy-five percent from my mom's side have it," she says. "It's been an ongoing situation for generations, and now I'm willing to get tested just because I want to know for myself."
If she tests positive, she hopes to be enrolled in the clinical trial run by the DIAN Trials Unit, which is testing two promising drugs.
An Incredible MotherIt's the intensity of Duarte's love for her mother that made the decision to get tested even harder.
"I worry about what will happen to her if I get it and she's still alive," she says.
Cardona, a teacher's aide for kindergarten through 8th graders in Chicago for 29 years, was a tough but loving mom who moved her children to the suburbs when they were young to get them away from the bad influences in their old neighborhood.
"She took two buses and two trains to go to work everyday so we could have a better life," says Duarte, the second of three children.
Though Cardona had been becoming increasingly forgetful over the years, it wasn't until she retired that the family realized how much of her decline she'd been hiding.
"She finally decided to tell me the reason she retired was because she was being forgetful," her son Juan Duarte, 38, a police officer outside Chicago, tells PEOPLE.
Concerned, he took her to a doctor.
"They had her go through a battery of tests and that was rough," he says. "They'd give her a couple of names, then have her repeat it a couple more times, and she couldn't."
The doctors diagnosed her with dementia, he says.
After a neighbor found Cardona wandering in the snow in her nightgown with no shoes on, it was clear she could no longer live alone – which is how she eventually ended up in Duarte's care in the summer of 2011.
Though a self-described "party animal" who owned her own sports bar, she didn't hesitate to take her mother in.
"My mom has been there for me since day one," says Duarte, who is single and has no children. "Why would I turn my back on her when she needs me the most?"
Life with MomThe two women quickly became inseparable with, Duarte building her life – and her schedule – around her mother's needs.
She makes sure Cardona has plenty of fun as well – from happy hours and dinners out with her friends to shooting pool and seeing her beloved Cubs play in Chicago.
"I would love to take her to see her show live," she says.
She's also been trying to make her mother's dreams come true with the time she has left.
"There's three places my mom said she wanted to go," Duarte says. "She always said this when we were growing up – Las Vegas, Disney in Florida and Hawaii."
Courtesy Daisy Duarte
"That's too expensive," she says. "I'll never make it there."
In October 2012, Cardona took a turn for the worse – which landed her in the hospital for three weeks. Doctors told Duarte she had Creutzfeld-Jacob disease, which is similar to mad cow disease
"They told me she had six to nine months to live," she says. "I shut my bar down because I did not want to put my mother in a home."
She frantically searched the Internet for a possible treatment or cure – which led her to Dr. Ances, who finally managed to give the family the correct diagnosis.
"After our first meeting I said, 'I have good news and bad news,' " Dr. Ances tells PEOPLE. " 'The good news is it's not CJD, which is a rapidly fatal disease. The bad news is I think it's something else that is potentially not treatable, but I need to do some more tests.' "
Genetic tests confirmed Cardona had one of the three genes known to cause early-onset familial Alzheimer's – which is when Duarte decided to get tested herself.
Duarte worries about positive results not for herself, but for her mom should she have the disease and become symptomatic while her mother is still alive.
"I promised her – 'You will never go in a home,' " she says. "To me, this is what I live for. She's my world. The only time I get really emotional is to think of anything happening to my mom."
To find out the results of Daisy Duarte's genetic testing, pick up this week's PEOPLE, on newsstands Friday
Courtesy: Daisy Duarte