Grandmother with Alzheimer's recalls childhood song while comforting newborn

It happened when Setsuko Harmon was comforting her granddaughter.

— -- One first-time grandmother living with Alzheimer's disease was able to recall a childhood Japanese song when comforting her newborn granddaughter.

Setsuko Harmon was diagnosed with Alzheimer's eight years ago, her daughter Christine Stone told ABC News.

"She just started showing signs," Stone, an office manager living in Florence, South Carolina, continued. "She would drive places and forget where she was going. She'd drive the car until she was out of gas."

It was then that she and her father, Bob Harmon, discovered that Setsuko Harmon, 77, had short-term memory loss.

So when Stone, 39, and her husband of five years discovered they were expecting they couldn't wait to tell their families. It didn't matter that Setsuko Harmon wouldn't remember and she'd have to tell her mother multiple times.

Stone even created a video compilation of all of the times, which was in the hundreds, she told her mother she was expecting.

"It was a fun time. It was exciting to watch her reaction every time I'd tell her," the new mother recalled.

Stone gave birth to her first child, Sadie Mae Stone, on Oct. 11.

The new mom said she feels the new baby has motivated her mother to do more.

"Sometimes my dad would have a hard time getting her here [to South Carolina.] But now they've been coming here every week," Stone said. "My dad will say, 'Let's go see Christine's baby!' And she comes excited.'"

In fact, on a recent visit last month Setsuko Harmon sang a childhood Japanese song, "Donguri Korokoro," to Sadie Mae when comforting her.

"It really is special to watch her sing it to Sadie because I remember her singing it to me," Stone said. "She would sing all these Japanese songs ... when she would wash my hair in the shower."

"I thought it was pretty special that she can remember songs from way back when; over 30 years ago," she added.

Setsuko Harmon's husband of 46 years, Bob Harmon, told ABC News in a statement that he often encourages his wife to "sing a song or tell [me] a story" before bed.

Stone said she shares videos of her mother to raise awareness on the effects of Alzheimer's disease. "More research and funding can be done," she added.