The bittersweet strains of lyrical exits

With the country musician Glen Campbell's announcement that he will do a final tour and album while he is still just ahead of his battle with Alzheimer's, a look at other artists who have allowed the end of their lives to inform their art.

The musician Glen Campbell, who was diagnosed with Alzheimer's disease, is planning a farewell tour before retiring from the music business.

It was bittersweet when the American country musician Glen Campbell recently announced his final tour and album, Ghost on the Canvas. Campbell is suffering from Alzheimer's, you see, and in the times that he knows anything, he knows that his lucidity is diminishing.

It's a heartbreaking disease, more so for those watching, who find themselves unknown to their loved one. In supporting him in this tour, Campbell's wife, Kim, and his three children with her who act as the band will be doing much more than playing music with him. They must be ready to move if he forgets his lines, his music or even where he is, over the course of a four-month tour around the world. Anyone would find that number of dates disorientating; for a man with Alzheimer's, the potential confusion is hard to imagine.

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So why tour? Why do all the hard work on an album? Why not simply enjoy what time you have in your right mind at home with family and friends around you?

Well, perhaps it is partly to do with the healing power of music, well-documented in neural illnesses such as Alzheimer's and Parkinson's. In his fascinating and enlightening 2007 book Musicophilia, the psychiatrist Oliver Sacks describes how even people suffering with extreme forms of dementia can be brought back temporarily to lucidity using music that they used to listen to or play. He describes music as a sort of vessel in which our memories are carried, and as an old favourite song is sung, the memories of its context flood back. It's no cure, but it does seem to offer some short-term relief.

For Campbell, as for many ageing rockers, the reprising of his old classics may indeed pique memories of his heyday in the late 1960s and 1970s. In his case, though, its effect must be all the more poignant for its rarity.

That's the tour explained, but this is an album of new music, which perhaps represents another possibility: like many artists, he simply cannot stop exercising his particular form of expression. And the legacy of a final album by someone who can see his own demise ahead is something that cannot fail to be moving.

Death has always had a powerful effect on the musical reputations of musicians. The small corpus of work by Jeff Buckley, for example, and particularly his heart-rending version of Hallelujah, are made all the more poignant by the knowledge of his premature and unexpected loss, when he drowned in 1997. The macabre glorification, too, of the so-called 27 Club, including its recent tragic new addition Amy Winehouse, has seen cult status assigned to the last records of the club's members.

But there is an entirely different sort of pathos to be found in the final albums of those artists who are aware of their imminent departures, and it is rarely of a tragic, self-pitying tone. George Harrison, for example, recorded his final album Brainwashed while aware that he was dying of cancer, and he continued to work until two months before he died. Yet it is an uplifting record - philosophical and pensive, certainly, as Harrison was wont to be, but gently witty rather than gloomy.

The rock musician Warren Zevon, too, recorded The Wind in 2002 while dying of an inoperable cancer - and refusing cancer therapies. He talked about his illness at length while recording, being filmed for a VH1 documentary and collaborating with the likes of Bruce Springsteen and Emmylou Harris, and the final result, especially the cover of Bob Dylan's Knocking on Heaven's Door, has a certain mordant humour that was typical of Zevon.

Freddie Mercury, meanwhile, kept his Aids a secret from the public until the day before he died, though his increasingly gaunt appearances in the years before he finally succumbed in 1991 had caused speculation. The final Queen album was made mainly from recordings that he had effectively stockpiled with the band in his final months. The Mercury-penned A Winter's Tale, though, recorded just before he died, is a warm, joyful, nostalgic song written at a time when he had every right to feel sorry for himself.

In Johnny Cash's American series, produced by Rick Rubin, the third and fourth albums feature song choices that see him looking back at a life lived, if not always well, then certainly passionately. The single Hurt, from American IV: The Man Comes Around, a cover of the Nine Inch Nails song, is a grinding, gutting acknowledgement of the pain of regret released not long before his death.

Interestingly, though, one of the B-side tracks on Hurt was Wichita Lineman, probably the song for which Glen Campbell is best-known. Written by Jimmy Webb, it seems especially appropriate now: for the next four months, at least, Campbell, like the lineman, is still on the line.