Riverdance's annual dance-a-thon took place on Thursday outside Dublin's Gaiety Theatre, with all proceeds going to this year's charity partner, the Alzheimer's Society of Ireland.

The professional Riverdance team performed in the dance-a-thon at lunchtime and returned later in the evening, with dancers of all ages also taking part throughout the 12-hour Irish dancing event that began at 10am on Thursday morning.

The cause is particularly close to the Riverdance team following their former manager Ronan Smith's diagnosis with early onset Alzheimer's a number of years ago.

Speaking about the decision to support the Alzheimer's Society of Ireland (ASI) this year, Riverdance executive producer Julian Erskine said it had a "really personal" meaning for the team.

"This year it's really personal because our ex-general manager Ronan Smith was diagnosed a few years ago with Alzheimer's," Erskine told RTÉ Entertainment.

"Ronan, separate to Riverdance, is a very close friend of mine and so I thought this is the year for Alzheimer's. Ronan also has a close relationship with the Gaiety; he's produced the Gaiety panto for the last 15 years. So there's a combination of the Gaiety, Riverdance, Ronan and Alzheimer's. It was an obvious choice."

Ronan Smith, who since his diagnosis has become heavily involved with the ASI and now sits on the society's board of directors - the first person with Alzheimer's to do so - said he was "touched" by Riverdance's support this season.

"I feel very touched because, obviously, I worked over that long period with Riverdance and I think it's a really good charity and it's good that it gets its turn," he said.

"I'm very touched because I think it's a very personal decision from [Riverdance co-founders] John (McColgan) and Moya (Doherty) to put the ASI as the focus this year."

Smith cared for his father while he lived with Alzheimer's, and one of his aims through the ASI is to break down the stigma that is often associated with the disease, particularly during his father's time.

"I suppose I jumped in when I got the diagnosis because I had worked with the Alzheimer's Society in its early days," he said. "So I was very quick to engage with the society and the first thing I absolutely immediately did was I outed myself very publicly.

"I just feel it's so unfortunate where the stigma when my father had the disease, was so acute, to where the carers of people with the disease were avoided by the neighbours because they were embarrassed and it was like a taboo."

The annual dance-a-thon not only raises awareness for the selected charity partner, but also celebrates the legacy of Riverdance, and producer Erskine described the day as his favourite of the year.

"It's fantastic, we love it, and it's my favourite day of the year," Erskine said. "It's the combination of the Riverdance stars of today and the Riverdance stars of tomorrow and we get them all out there on the stage. What's great is, you don't just see the little kids looking at our dancers, our dancers are looking at the little kids, because that was them once - they all come through the same system."

Tina Leonard, Head of Advocacy and Public Affairs at the ASI, spoke about the positive effects Irish dancing can have on people with Alzheimer's and dementia, saying, "Studies into how useful dance is to dementia actually show that Irish dancing is one of the two best forms of exercise and dance for reducing risk of dementia, because there's so much coordination they have to do - so much footwork, so much focus."

Leonard also said there is a message for the public in how Riverdance are standing by their colleague and friend Smith through his diagnosis. She urged people not to shy away from those they may know living with the disease, just because they might be unsure of how to act.

"Ronan's colleagues at Riverdance said, 'How can we support you now on this new journey? How can we support you to be an advocate, how can we stand with you?'

"And that's how this relationship has come along - how we're charity partners this year," she said.