John Hinckley made the statement to a doctor who interviewed him in the past year at a Washington mental hospital. The statement is part of hundreds of pages of documents prepared for court hearings.
Hinckley, who shot and wounded Reagan in 1981, is seeking more freedom from the hospital. He has been allowed to visit his mother’s home in Virginia for up to 10 days at a time.
Government lawyers believe his trips should remain at 10 days.
A jury found Hinckley to be insane when he shot Mr Reagan in an effort to impress actress Jodie Foster.
He has spent most of the past three decades at St Elizabeth’s Hospital.
In recent years, doctors have said his mental illness has been in remission.
Hinckley said he still thinks about the actress, but only to ask himself “what was it about her that made me do this”.
Several hearings in the case ended this month, and a judge said he would likely rule in April or May.
A doctor who testified for the government noted that Hinckley regrets not being able to show or sell his art.
“I would like to be known as something other than the would-be assassin,” Hinckley said.
The documents also said a computer that Hinckley and others used at the hospital included searches for Jodie Foster, Reagan and assassination.