DIDN’T WE ALREADY KNOW ABOUT REAGAN AND ALZHEIMER’S?…. There was a fair amount of attention yesterday devoted to reports that Ronald Reagan’s Alzheimer’s disease was apparent, though never discussed publicly, during his presidency. I’m not sure why this is considered especially new.

Former President Ronald Reagan — who diagnosed with Alzheimer’s disease five years after leaving the presidency — elicited “shivers of concern” about his mental state as early as 1984, during his first term in office, according to a new book by his son, Ron Jr.

In his forthcoming memoir, “My Father at 100,” Ronald Reagan Jr. writes that he grew concerned that something was wrong with his father “beyond mellowing” in the early 1980s.

He goes on to say that — given what science has learned about when symptoms of Alzheimer’s arise — the question of whether he was suffering from the disease while in office “more or less answers itself.”

I realize that Republican reverence for Reagan has taken on a vaguely religious adoration, but I was under the impression that everyone, regardless of party or ideology, already believed Reagan’s Alzheimer’s symptoms were evident well before 1989. Perhaps the first-hand accounts of the former president’s son add some weight to the story, but I’d assumed this was common knowledge.

Indeed, we’ve heard many accounts like these for years. Steve M. noted an anecdote from CBS News’ Lesely Stahl, who was a White House correspondent for the first six years of Reagan’s presidency, who wrote in her book about saying goodbye to Reagan in the Oval Office on her last day on the job. An aide insisted Stahl was forbidden from asking Reagan questions or reporting on what she saw. She explained in her book what she saw:

Reagan was as shriveled as a kumquat. He was so frail, his skin was so paper-thin, I could almost see the sunlight through the back of his withered neck. His bony hands were dotted with age spots, one bleeding into another. His eyes were coated. Larry introduced us, but he had to shout. Had Reagan turned off his hearing aid?

“Mr. President!” he bellowed. “This is Lesley Stahl.” He said it slowly. “Of CBS, and her husband, Aaron Latham.”

Reagan didn’t seem to know who I was. He gave me a distant look with those milky eyes and shook my hand weakly. Oh, my, he’s gonzo, I thought. I have to go on the lawn tonight and tell my countrymen that the president of the United States is a space cadet. My heart began to hammer with the import. As the White House photographer snapped pictures of us — because this was a photo-op — I was aware of the delicacy with which I would have to write my script. But I was quite sure of the diagnosis.

Larry was shouting again, instructing the president to hand us some souvenirs. Cuff links, a White House tie tack. I felt the necessity to fill the silence. “This is my daughter, Mr. President,” I said. “Taylor. She’s eight.” He barely responded but for a little head tilt.

Click. Click. More pictures. A flash. “When I covered Jimmy Carter,” I said, “Taylor used to tell everyone that the president worked for her mommy. But from the day you moved in here, she began saying, ‘My mommy works for the president.’” I wasn’t above a little massaging. Was he so out of it that couldn’t appreciate a sweet story that reflected well on him? Guess so. His pupils didn’t even dilate. Nothing. No reaction.

These experiences were not uncommon. In his second term, it was routine for Reagan to forget the names of his top generals and cabinet secretaries. His wife was seen whispering answers to questions in his ear. By any reasonable measure, Reagan’s mental acuity was failing well before his presidency ended.

I suspect Reagan’s fans, and there are obviously many, will find all of this uncomfortable, and perhaps even insulting. They shouldn’t. The successes or failures of Reagan’s presidency can be judged on their own merits, whether he was showing the effects of Alzheimer’s or not.

But the historical record should nevertheless be clear, and given what we know, Ron Reagan’s new accounts should hardly be considered shocking.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.