0220 GMT November 28, 2020
Paul Harvey, 80, originally improvised the composition after being given four notes to play by his son, BBC reported.
A clip of the performance, which went viral, was intended to show how musical ability can survive memory loss.
The single of Four Notes — Paul’s Tune was aired on Radio 4's Broadcasting House for the first time.
Despite being diagnosed with dementia late last year, Harvey, a composer from Sussex, England, has continued to be able to play piano pieces from memory and create new ones.
His son, Nick, who posted the video in September, said it had been an "old party trick" of his father's to request four random notes and then improvise a song.
In the video, which has had more than 60,000 likes, Nick picked F natural, A, D and B natural for his father to play.
After the clip went viral, the performance was aired on Broadcasting House for World Alzheimer's Day on September 21.
This prompted listeners to ask the BBC to have the performance orchestrated, which led to the BBC Philharmonic's involvement.
'A new lease of life'
Hearing the recording of the single for the first time, Paul, who was joined by his son on the program, said: "It was very, very moving and very thrilling at the same time...
"It's quite amazing that all this has happened, and in my 81st year. It's fantastic.
"It's given me a new lease of life and after we've all finished here I'll go to the piano and find another four notes."
Nick said: "It was amazing — it was absolutely gorgeous."
Arlene Phillips, whose father had Alzheimer's, and is an Alzheimer Society's ambassador, said the piece was "so beautiful".
She said: "It's just incredible that four notes can stir so many mixed emotions."
Jason Warren, professor of neurology at the Dementia Research Center at University College London, said one reason people with dementia can continue to play music is because it "makes sense on its own terms".
"So unlike a lot of the tests and the things we might ask people with dementia to do in the clinic, for example, or in their everyday lives, music to some extent is almost self-contained."
However, he said what Paul did in his piece was "remarkable by any standard, because what that also shows is his creativity".
Nick said it was hoped the single would be released on all major steaming platforms on Sunday, November 1. All proceeds will be split between the Alzheimer's Society and Music for Dementia.