Regional audiences settling down to the James Keach documentary Glen Campbell: I’ll Be Me will likely experience a sense of déjà vu, considering the recent screenings of local filmmaker Michael Rossato-Bennett’s doc feature Alive Inside, which explored expanding use of music as a cognitive rehabilitation tool in nursing homes and beyond for people with dementia.

Rossato-Bennett, working closely with social worker Dan Cohen, captured compelling examples of the ability of music to trigger a restorative connection in the psyches of patients who have spent years languishing inside the unfamiliar space of their minds.

Personalized music, indeed, seems to stimulate life once again inside in what was thought to be a dead zone of sorts, but Keach’s film further challenges the assumption by asking, “Can music, a deep involvement in the creation and performance of music, help a person maintain a true and meaningful sense of themselves — how to be ‘me’ when you have no idea who ‘me’ is?”

That idea is the perfect narrative for a film, and the genial Campbell, now suffering from Alzheimer’s, shows us the gradual loss of identity, even among a caring community of friends, family and medical professionals doing all they can to keep the decline at bay.

Along similar lines, a film like the upcoming Stephen Hawking biopic The Theory of Everything, while not concerned with forgetting or losing memories and identity, focuses instead on Lou Gehrig’s disease, which locks the mind away, deep inside an atrophying body. Hawking never loses himself the way a dementia patient does; rather he becomes trapped inside the prison of a constantly dilapidating form.

The breakdown gives the impression of being fractured, less fluid because the body displays starts and stops over the course of its transition. In terms of music, the melody would be lost with no sense of rhythm.

But it is the melody that seems to hold the key for Campbell in Keach’s film, at least early on. It flows, lubricating the brain, charging the synapses, or maybe it is a function of something akin to muscle memory.

To watch him engage in the interactive musical duels onstage with his daughter — she’s on banjo, while he plays guitar — reminds audiences that Campbell was a fine session musician, not just a Country-Pop star with a handsome face and a soothing voice. He played on the seminal Beach Boys recordings and could whip up a bluesy, jazzy frenzy with his axe whenever the mood struck.

Eroding memory robs Campbell of the lyrics, but he continues to hold onto the melody with a death grip, which you know will inevitably start to loosen as well. We see awareness of it in Campbell’s eyes as he sits among his family and crew or with his doctors, all talking around him. He is the fading puzzle piece in a picture that is washing away as well and he can’t imagine where he fits.

Eddie Redmayne as Hawking in The Theory of Everything has the difficult task of somehow opening a pathway for audiences to follow to let us see and feel the alive and vibrant man inside that brilliant and beautiful mind.

The sadness we experience, in his case, is plainly visible to us in his frail body, but when we hear that computer-generated voice or peer into those eyes of his, there is no doubt that greatness stirs.

It is these contrasting moments, though, that matter even more for Campbell and those suffering with Alzheimer’s or other forms of dementia, because we get a sense that Campbell knows there is more for him to lose, but he isn’t exactly angry or full of rage — not yet. Instead he stares at the chalkboard before him being wiped clean.

There are still impressions up there, enough for him to fake his way through. He is, after all, a musician who can still improvise with the best of them, taking visual and context cues to make something out of nothing.

Campbell and his wife Kim went public early on when he was initially diagnosed, embarking on what would become a 151-day tour to support his final musical release. What they have given us, along with Keach in this documentary, is a chance to celebrate a wonderful life passing before all of our eyes.

The idea of music helping Glen Campbell hold onto a piece of the old Glen Campbell should inspire everyone to support the efforts of millions of others in need of resources to do the same. (Opens Friday) (PG) Grade: A (tt stern-enzi)