Spirit of the West frontman John Mann, who suffers from Alzheimer's, uses an iPad to assist him as he performs his final concert in Vancouver, Saturday, April 16, 2016. Though early-onset Alzheimer's has started to take away his musical memories, songs remain a vital outlet for Spirit of the West lead singer Mann. THE CANADIAN PRESS/Jonathan Hayward

TORONTO - Though early-onset Alzheimer's has started to take away his musical memories, songs remain a vital outlet for Spirit of the West lead singer John Mann.

As the new documentary "Spirit Unforgettable" shows, Mann still gets a lift from music, and it actually serves as a form of therapy.

"There is something called cognitive reserve that happens when he performs muscle memory," says Ben Murray, who produced the doc.

"He's able to perform onstage and function in a way that he can't necessarily in everyday life now, which is amazing. So that's been a really important part of his story and journey through the illness."

"Spirit Unforgettable" makes its world premiere at the Hot Docs Canadian International Documentary Festival in Toronto on Saturday.

It follows the 53-year-old's journey with his disease and tracks the history of the Vancouver-based folk-Celtic band, which was formed in 1983 and has hits including "Home for a Rest."

Cameras follow the group for a year, in the leadup to a show at Toronto's Massey Hall, and show Mann as he tries to recall the origins of their songs — if he can remember them at all.

"I think what the film conveys is the amazing network of support involved in really getting someone through this," says Murray.

"When he performs onstage now he uses an iPad to read, which is operated by one of the other band members, and they've found a way to insulate and work around the illness in a way to keep him performing.

"Because he gets such a lift from being onstage."

Mann was diagnosed with the disease in 2014. Meanwhile, drummer Vince Ditrich is also battling kidney failure.

As such, the group doesn't plan to perform in concert anymore, and announced that their show at the Commodore Ballroom in Vancouver earlier this month was their last.

Mann, who is scheduled to appear at Hot Docs, is exploring alternative treatments and "fighting extremely hard against the disease."

"The reality, sadly, as those of us who have experienced it first-hand know, there's only one direction for that progression," says Murray.

"(Mann and his wife) have been fighting it hard, but there are certain realities now that they're grappling with, because the disease progresses."

News from © The Canadian Press, 2016