Laura Mercer woke up one night and didn't know who she was.

Her husband, Greg, heard her babbling and found her in another room, holding a phone upside down and speaking into the earpiece. It was around 2 a.m. and Laura had turned on lights throughout their house in southeast Charlotte.

Laura?

She stared up at Greg with a blank look.

She didn't recognize her husband. She didn't know where she was. Nothing made sense.

Laura was a hard-charging public relations executive capable of flawlessly managing hundreds of details at home and in the office. She paid the bills. Kept up with the children's schedules. Brought home the six-figure salary.

Greg worried she was having a mental breakdown.

First thing in the morning, he took her to the doctor, who ordered an MRI. As they waited, Laura happily chatted with the empty chairs. Greg was terrified.

Something was obviously wrong with Laura's brain. Doctors put her through tests and tried different drugs. Laura gradually regained her sense of self, but she never returned to work. She couldn't remember what people told her. She lost herself in the middle of sentences, struggling to find the words. She needed help doing simple things.

Even so, when they finally got the diagnosis after two agonizing years, it seemed unthinkable:

Laura has Alzheimer's disease. She is 50 years old.

Laura and Greg had never heard of anyone so young with Alzheimer's. Like many people, they assumed it was an old person's disease. They thought it took you after you turned gray and wrinkled, after you had made your contributions to the world and held your grandchildren.

But early-onset Alzheimer's is not unusual. Of an estimated 5 million people with the disease, half a million - one in 10 - were diagnosed before they turned 65.

Would Laura live to see their son, Cortland, graduate from college?

Would she hold on long enough to see their daughter, Sarah, fall in love and marry?

How long, she asked, before I become a vegetable?

Neurologists couldn't answer her questions. So Laura quit asking. She decided to live in the moment. When she wrote her first blog, she didn't describe her agony at learning she has Alzheimer's, her anguish over Cortland's tears or her fears about tomorrow. Instead, Laura described walking in the mountains with Greg after they told their children.

"It was a beautiful day," she wrote. "And there are many more to come."

Day by beautiful day, Laura Mercer wakes up resolved to do whatever she can to keep her memories - and herself - alive.

Some people try to hide their Alzheimer's while they can. Not Laura. She tells the woman next to her in the YMCA locker room, and the shopper at the Harris Teeter. Anyone who will listen. Laura wants to educate people about Alzheimer's. She wants to raise money to find a cure. She wants to help others succumbing to the disease.

Laura doesn't want to lose her mind.

Sporadic symptoms

A lot of us have memory lapses. That's not Alzheimer's.

Alzheimer's is why Laura remembers only certain parts of stories and only certain stories, and why she repeats those same stories day after day, sometimes several times in a day. It's why she has trouble organizing her thoughts and following conversations, why occasionally a bewildered look will pass over her face - not because she can't remember what someone just said, but because she can't make sense of the words.

It's why she hasn't worked in three years. And stops mid-sentence to ask, "What was I talking about?" And can't read a lengthy novel. And can't balance a checkbook.

Laura's brain cells are dying.

Our brains are made up of billions of nerve cells called neurons. Some help us remember. Some control muscles. Others help us hear and see. Alzheimer's destroys the neurons, and disrupts the way they connect with each other.

As the cells die, Laura's brain shrinks.

How it spreads

The area of the brain first affected is the hippocampus, which helps form and store new memories.

The reason Laura may ask her son the same question three times in half an hour is because her brain cannot physically store the memory of what he just told her.

Next affected is the cortex, which is responsible for thinking, planning and retrieving memories. As cells in the cortex die, so will Laura's memories. But in reverse order, from most recent to oldest.

That's why some Alzheimer's patients eventually don't recognize their children or their spouses. Those memories are wiped out. An 80-year-old may think he's 20 and has never married. The reason he talks to the mirror is because he sees an unfamiliar 80-year-old man staring back at him. Not only does he not recognize his family, he doesn't recognize himself.

He has moved back in time.

The prognosis

Alzheimer's is often described as "an endless funeral." In its final stages, it may take away a person's ability to talk, walk, even swallow.

"When the brain dies, so does everything else," said Teresa Hoover of the Alzheimer's Association. "It's the brain that tells our heart to beat, our lungs to breath, our liver to function. All of that eventually will shut down."

Each person experiences the disease in a different way, Hoover said, so there's no way to predict what will happen to Laura. No way to know how long she will live. Statistically, the length of time from diagnosis to death is nine years. But some people live only a year; others, 25 years. The time from diagnosis to death is a year or two shorter for people diagnosed with early-onset Alzheimer's.

"But once again that's a meaningless number," Hoover said, "because I know people who were diagnosed in their late 40s and are now in their 60s."

Laura is in an early stage of early-onset Alzheimer's. She remembers that she doesn't remember.

What she's learned

Greg asked Laura after the diagnosis what she wanted to do with the rest of her life. Take a trip around the world? Whatever she wanted, he promised they would do.

Laura had always dreamed of traveling in Europe. Not now. She had always measured her worth by her job. Not now. What matters now to Laura is being with family and friends.

Cortland, student body president at UNC Asheville, admired his mother for her successful career at Price McNabb and Eric Mower & Associates. She once told a TV reporter that "I'm a better mother when I work."

Cortland said he admires her even more for the way she has embraced this dramatic unraveling not only of her life, but of her definition of herself.

"I didn't see her as being able to find value in other things the way she can now," he said. "The little things: Watching birds on the back deck, watching her tulips growing, cooking a meal."

He said his mother told him and his sister, Sarah, a teacher in Chatham County, that she would never forget who they are. She would never forget she loved them.

Cortland knows that's one promise his mother may not be able to keep.

Memories kept

Laura can tell that she's losing memories. She still remembers her childhood on Long Island, her college years at UNC Chapel Hill, her wedding in 1982, her first job as a newspaper reporter in Wilmington, and her public relations career in Charlotte.

The problem is her short-term memory.

She forgot where she parked her car at the mall so many times, she now relies on valet parking. She ordered the same gift basket twice in the same day for the same friend. She didn't remember to open the garage door one morning and backed her car into it.

She bought a Christmas present for Greg six months ago and told a friend where she hid it - and it's a good thing because Laura forgot.

Hope in science

Laura doesn't think about one day waking up and not knowing the most important people in her life, her husband, their children, her two sisters. She doesn't think about dying young. She knows that could happen.

"I don't worry," she said. "I do get frustrated. But as healthy as I am now and with all the research going on, I believe there's a real opportunity to see, if not a cure, some real scientific advances."

She hopes to keep remembering until science catches up to her.

She believes science will catch up with her.

Laura is trying to keep her brain active, trying to slow down her Alzheimer's. She takes Aricept and Namenda, which can help delay or prevent symptoms from getting worse for a time. She works on jigsaw puzzles and sews needlepoint. She writes a blog. She takes water aerobics classes. She naps every afternoon. She eats healthy food. She drinks green tea. She tries to remember all she has to do today without thinking about tomorrow.

"I love the way Laura is approaching it," said her sister, Mary Hartley, who lives in Pittsburgh. "She has today and she's thoroughly enjoying it. It's wonderful to see that Laura, because the other Laura was always so driven."

A spouse's journey

Greg now pays the bills and remembers birthdays and files insurance claims and plans dinner parties and takes care of all the other chores Laura once handled so effortlessly. He lost 40 pounds, to be in better health to care for her. They updated their wills and took care of other legal matters.

Laura remains self-sufficient enough that Greg goes off to work as usual to Red Moon Marketing, where he is senior vice president. She has a "husband-approved driving zone," from their house west to the Harris YMCA and north to the Cotswold Harris Teeter.

When Greg gets back at night, Laura has a home-cooked meal waiting. That's the new Laura. The old Laura served takeout.

"On my best days, I feel so grateful for the 30-some years Laura and I have been together," Greg said.

"Other days, I say, 'Why me? Why us? Why at such a young age? Why Laura?'"

The hardest question is always: "What am I going to do without my partner and the love of my life?"

That is why Greg, like Laura, tries not surrender to fears about tomorrow. As best he can, he lives with her in the moment. Because, for today at least, she is still Laura.