It’s the end of the era for Vancouver band Spirit of the West as the group prepares for their final show together after more than 30 years.

On Saturday evening, the band will perform for the last time at the Commodore Ballroom to a sold-out crowd, citing lead guitarist John Mann’s health struggles as the reason for their departure.

Mann first battled colorectal cancer, then was diagnosed with early-onset Alzheimer’s at the age of 51.

"It's been hard, since Johnny's got a serious struggle ahead of him, being diagnosed with early-onset Alzheimer's,” said guitarist Geoffrey Kelly. “That’s really going to change the trajectory of things, hence these farewell concerts.”

Mann isn’t the only one who has faced health challenges: drummer Vince Ditrich has missed a lot of the tour due to kidney failure, though bandmates say he will return for Saturday’s show.

The Celtic-flavoured rock act began in 1983 with just three musicians, quickly growing to six musicians and producing more than 13 albums – five gold, three platinum.

Mann’s diagnosis has changed the way the group performs, and an iPad has been utilized as a teleprompter.

“Musically, we’ve had to really rethink how we go about things,” said Kelly. “We all shadow him now. And vocally, if he loses his place in a song, either Matthew our guitar player who's got a great voice will kind of tentatively be watching Johnny."

It will be an emotional farewell for the band, who says they will have to work harder on maintaining their friendships.

“What exactly the emotions are is really hard to say,” said multi-instrumentalist Hugh McMillan. “I’ve definitely had flashes where I grip the edge of my seat and say ‘oh my goodness, might be a tear here – oh nope, something in my eye.’”

The band plans to rally around Mann, planning what they call “Johnny Jams” once a month.

"Keeping the music happening... keeping his neurons firing,” said McMillan. “Across the board, music therapy is becoming huge.”

As fans prepare for the final show, Spirit of the West has a message for those who “stuck with us all these years.”

“Thank-you for supporting us for 32 years,” said Kelly. “Really we’ve had help along the way… but it all comes from the fans. “

With files from CTV Vancouver’s Julie Nolin