Manson, 77, did not attend the parole hearing.
The board was expected to make a ruling Wednesday afternoon, and it's not clear why the decision was rendered so quickly.
Before the hearing, his state-appointed attorney, DeJon R. Lewis, said he would like to see Manson transferred to a mental hospital.
Manson and Lewis, 45, who was a small boy at the time of the "Manson family" killings in 1969, haven't yet met.
"He didn't come to my interview either, so I have never met him," Lewis said in an exclusive interview with CNN.
"I went to go interview him last month. I asked the correction officers if was he coming out of his cell, and they said nope. And I said OK, who's the next inmate?"
Lewis planned to tell the parole board that Manson is in need of psychiatric care at Atascadero State Hospital, about 95 miles southwest of the state prison in Corcoran, California, where he is serving a life sentence.
Corcoran is about 170 miles northwest of downtown Los Angeles.
A recent prison photo released to CNN shows Manson yielding to old age -- with unruly long gray hair and a full beard, but with subdued eyes that no longer flash a signature Helter-Skelter menace.
Manson still bears a swastika tattooed on his forehead above, and between, his eyes.
"Charles Manson does not need incarceration at this point in his life," Lewis said. "He needs hospitalization."
"I mean the issues in regard to his psychiatric makeup and the health concerns that a 76- or 77-year-old man would need," he explained. "What he did was heinous from what he said. How many years has he been in prison? I was just a little boy, but after all these years, has there been any rehabilitation? I don't know. He probably needs more hospitalization than incarceration."
Manson was initially sentenced to death for the 1969 slayings of actress Sharon Tate and six others by a group of his followers as part of what prosecutors said was an attempt to incite a race war.
His death sentence was changed to life in prison after California's death penalty was overturned for a period during the 1970s.
Manson has been denied parole 11 times. The last time he appeared at his parole hearing was 15 years ago.
In an interview Tuesday with CNN, Debra Tate, the sister of Sharon Tate, said she has been attending Manson's parole hearings for the past 15 years -- and Manson has not shown up.
Tate agreed with some legal experts' observations that Wednesday's parole hearing could be the last one for the aging Manson.