Glen Campbell's 25-year-old youngest daughter, is touched at how supportive audiences have been for her father while on his final good bye tour, Glenn was diagnosed with Alzheimer's disease 18 months ago.

"He walks on stage and they start cheering like crazy and stand up," she said. "They give him so much love off the bat, and that helps him do better shows. It encourages him."

The 76-year-old singer is performing his 1960s and '70s crossover country hits, including "Rhinestone Cowboy," "Wichita Lineman" and "Gentle on My Mind," as well as other music, around the country as part of his Goodbye Tour.

The younger Campbell, a banjo player who is one of three of Glen Campbell's children performing on the tour, said signs of her father's illness are evident at his concerts. The disease, a form of dementia, has no cure and worsens as it progresses. "You definitely know something's up," she said. "He does repeat himself a lot. He does rely heavily on the teleprompter these days. Sometimes he'll go through a show with minor glitches and it'll seem normal, but other times it's apparent."

At the height of his fame, Glen Campbell was one of the most famous musical performers around. His popular TV show, "The Glen Campbell Goodtime Hour," which aired from 1969 to 1972, attracted 50 million viewers a week. Compare that to the 30 million who tune in for the "American Idol" finals, the most watched non-Super Bowl TV program these days.

Born one of 12 children in Arkansas to a family of sharecroppers, Campbell learned guitar at a young age and started performing in bands while a teenager. In the early 1960s, he moved to Hollywood with $300 in his pocket and got work as a session player. He recorded with top artists of the era, including Nat King Cole, Dean Martin, Merle Haggard and Jan & Dean. He played guitar on Frank Sinatra's "Strangers in the Night" and he performed on The Beach Boys' acclaimed "Pet Sounds" album.

After he began recording his own songs and getting some hits, he attracted the attention of Tommy Smothers, who caught him on a guest appearance on "The Joey Bishop Show." Impressed with his wit and charm, Smothers booked him as the host of "The Summer Brothers Smothers Show." When ratings skyrocketed, CBS offered Campbell his own show and "The Glen Campbell Goodtime Hour" was born.