When Nancy Reagan (search) appeared at a fund-raising gala in Los Angeles last month to promote the expansion of stem cell research, it was the latest stop in her evolution from Hollywood socialite to Alzheimer's (search) activist.

As first lady, Mrs. Reagan came under sharp criticism for focusing on designer clothes and White House parties, while sometimes ignoring important social issues.

Her husband's decade-long struggle against Alzheimer's changed all that, thrusting her into a political battle over the funding of stem cell research that is opposed by anti-abortion activists and the Bush administration.

"Ronnie's long journey has finally taken him to a distant place where I can no longer reach him," Mrs. Reagan said at the fundraiser, in her first public comments on the controversial research. "Because of this I'm determined to do whatever I can to save other families from this pain. I just don't see how we can turn our backs on this."

President Reagan was diagnosed with Alzheimer's in 1994, when he was 83 years old, and Mrs. Reagan devoted herself to his care. That dedication, as well as her fight against Alzheimer's, helped to soften her image and perhaps reshape her legacy.

"She's been an absolute model caregiver, totally committed and devoted to her husband," said Sheldon Goldberg, president of the Alzheimer's Association. "It's been a tragedy for her, but she has offered extraordinary leadership on finding a cure for this disease."

In 1998, Mrs. Reagan authorized the Alzheimer's Association to establish the Ronald and Nancy Reagan Institute for Research, which has raised about $17 million so far. More recently, she has become a prominent advocate of stem cell research.

Stem cells are the body's building blocks, which scientists believe can be coaxed into specific cell types in order to repair organs or treat diseases including Alzheimer's, Parkinson's and diabetes.

Because the cells are usually taken from embryos, which are then destroyed, the research has met fierce opposition from anti-abortion activists, who believe that life begins at conception.

While President Bush has committed some federal money toward stem cell research (search), he also ordered sharp limits on the practice, funding research only on stem cell lines created before August 2001.

That led Mrs. Reagan and others — including some anti-abortion Republicans in Congress who have had personal experience with debilitating disease — to urge Bush to reconsider his position.

"It's hard to overstate or overestimate the power of her impassioned plea for the Bush administration to reform its stem cell policy," said Daniel Perry, President of the Coalition for the Advancement of Medical Research. "She's given permission for very conservative, anti-abortion Republicans to disagree with Bush. It's a courageous stance against a president of her own party."

Much still is not known about Alzheimer's, which afflicts some 4.5 million mostly elderly Americans. The disease causes a gradual loss of brain cells, which depletes memory and thinking skills over time. Eventually, the loss of brain function can cause death.