The TRUE story behind The Notebook as star Gena Rowlands' own battle with dementia is laid bare in devastating echo of her on-screen role

The Notebook starring Rachel McAdams and Ryan Gosling is perhaps one of the most romantic films of all time.

But it's not just McAdams and Gosling who captured our hearts two decades ago as Allie and Noah, but also Gena Rowlands and James Garner who play the couple in their twilight years.

On Tuesday, 20 years after The Notebook was released, the director and Rowlands' son Nick Cassavetes revealed that his mother had been living with Alzheimer's for the past five years, mirroring the storyline of her character in the hit film, based on the Nicholas Sparks novel.

But many fans may not be aware that the movie, which grossed more than $117 million worldwide, was actually inspired by a true story.

Sparks revealed that he took inspiration from his ex-wife's grandparents and their epic love story when writing the story of characters Noah Calhoun and Allie Hamilton.

The Notebook starring Ryan Gosling and Rachel McAdams was released 20 years ago and was based on a novel by Nicholas Sparks

Sparks has revealed that the story of Noah and Allie was based on a real-life couple. Pictured here are James Garner and Gena Rowlands in the 2004 film

The Notebook tells the poignant love story between working-class Noah (played by Gosling) and wealthy Allie (McAdams), who fall deeply in love while defying societal differences. 

The 2004 film cuts between the unlikely couple's passionate youth and the present day, where an elderly Noah, disguised as 'Duke,' reads their story from a notebook to a fellow nursing home resident – his wife, Allie (played by Gena Rowlands), who has dementia. 

Sparks revealed that the tale was inspired by former wife Cathy's grandparents, who also enjoyed a passionate summer romance, only to be separated by her grandmother's strict parents.

Cathy's grandmother went on to be engaged to another man - just like Allie does in the movie - but she never forgot about Noah and eventually returned to him and the pair got married.

'Cathy's grandparents, they were this great couple and in many ways, their story [is The Notebook],' Sparks told The Wall Street Journal back in 2016. 

A few years later in 2021, the Herald-Tribune reported that Sparks told a crowd in Bradenton, Florida, that his former spouse's grandparents met as teenagers and enjoyed a romance one summer.

'As I'm trying to figure out what story to write, I got this one story but I didn't know if anyone was going to like it,' Sparks said. 

'I thought it was kind of sweet and it was a story that I thought I could write... that story eventually became The Notebook.'

Rachel played the role of Allie Hamilton while Ryan portrayed Noah Calhoun in the blockbuster film

Ryan, who is now a father-of-two, was just 23 years old when fans fell in love with him as Noah

Sparks revealed that the tale was inspired by former wife Cathy's grandparents. Sparks and ex-wife Cathy pictured in 2013

According to Sparks, Cathy's great-grandparents separated their daughter from her newfound love at the end of the summer they had met.

However, just like the character of Noah, Cathy's grandfather didn't give up and continued to write letters of affection to her grandmother every day.

'They were separated for years and she [got] engaged and she [came] back and they [fell] in love,' Sparks added to the WSJ.

Sparks has never revealed the real names of his ex-wife's grandparents but he did confirm that Noah's devotion to reading Allie the story of their lives to help bring back her memory was also inspired by his ex-grandfather-in-law.

'Toward the end of her life, she [got] dementia... and he's with her, and showing her... drawings and photographs,' he explained.

'He didn't have a notebook, but it was an album that he would walk her through and tell her about their lives together. I just thought there was something really beautiful about that entire concept and so I tried to do it in The Notebook,' Sparks added.

It's unknown exactly how long Cathy's grandparents were together, but they were in a relationship for more than 60 years. 

Gena Rowlands, who played an older Allie in the film, has revealed that she has Alzheimer's  

The Notebook was released in the US on June 25, 2004, and grossed more than $117 million worldwide

Sparks wrote of the real-life couple on his website: 'What I most remember... is the way they were treating each other. The way his eyes shined when he looked at her, the way he held her hand, the way he got her tea and took care of her.

'I remember watching them together and thinking to myself that after sixty years of marriage, these two people were treating each other exactly the same as my wife and I were treating each other after twelve hours [of marriage].'

As the movie marked 20 years since it was first released, the family of 94-year-old Rowlands revealed that - just like her character - she had been suffering from Alzheimer's for the past five years and was now 'in full dementia.'

The heartbreaking health update was announced by her son, Cassavetes, to Entertainment Weekly. 

Cassavetes said: 'I got my mom to play older Allie, and we spent a lot of time talking about Alzheimer's and wanting to be authentic with it, and now, for the last five years, she's had Alzheimer's.

'She's in full dementia. And it's so crazy — we lived it, she acted it, and now it's on us.'

In a 2004 interview with O Magazine, Rowlands opened up about how her mother's struggle with the disease impacted her decision to play Allie.

'I went through that with my mother, and if Nick hadn't directed the film, I don't think I would have gone for it — it's just too hard. It was a tough but wonderful movie.'