** FILE ** In this Sept. 6, 2012, file photo, singer Glen Campbell performs during his Goodbye Tour in Little Rock, Ark. Campbell finished off his Goodbye Tour on Friday night, Nov. 30, 2012, in Napa, Calif., but is considering scheduling more dates in 2013. The singer has Alzheimer's disease. (AP Photo/Danny Johnston, File)

Photo by: Danny Johnston

** FILE ** In this Sept. 6, 2012, file photo, singer Glen Campbell performs during his Goodbye Tour in Little Rock, Ark. Campbell finished off his Goodbye Tour on Friday night, Nov. 30, 2012, in Napa, Calif., but is considering scheduling more dates in 2013. The singer has Alzheimer's disease. (AP Photo/Danny Johnston, File)