WASHINGTON (AFP) - US President Barack Obama on Saturday (March 12) praised Nancy Reagan's efforts to raise awareness about Alzheimer's and stem cell research, one day after the former first lady was buried in California next to her husband.

Former US president Ronald Reagan, whose White House tenure stretched from 1981 to 1989, suffered from Alzheimer's disease after leaving office and went into a long decline until his death 12 years ago.

"We were inspired by how, in their long goodbye, Nancy became a voice on behalf of millions of families experiencing the depleting, aching reality of Alzheimer's disease," Mr Obama said in his weekly radio address.

Mrs Nancy Reagan died on Sunday of heart failure at the age of 94 at her home in the Bel Air suburb of Los Angeles and was buried beside her husband at the Reagan presidential library.

The former first lady not only became a tireless advocate for Alzheimer's research but also stem cell research.

"When I signed an order to resume federal stem cell research, I was proud that she was one of the first phone calls I made," Mr Obama said.

While in the White House, Mrs Reagan actively participated in her husband's campaigns, approved members of the president's cabinet, and was the face of the administration's Just Say No drugs campaign.

In addition, Mr Obama called her a staunch supporter of America's veterans and an advocate for mammograms after her own battle with breast cancer and a mastectomy.

In his address, Mr Obama said that he has "never been more optimistic that we will one day find a cure for devastating diseases like Alzheimer's".

"And I can think of no better way to honor our former first lady's legacy than by working together, as one nation, toward that goal," he said.

The former first lady's funeral brought together Hollywood stars and political powerbrokers, including First Lady Michelle Obama, former first lady Hillary Clinton and former president George W. Bush.