Journalist Greg O'Brien was just 59 when he was diagnosed with early-onset Alzheimer's, the same disease that killed his maternal grandfather and mother. In his memoir, On Pluto: Inside the Mind of Alzheimer's, O'Brien chronicles what it feels like to slowly lose his memory.

Since the book was published in September 2014, he has spoken at events and been interviewed more than 110 times, participating on panel discussions and delivering keynote addresses as an "embedded reporter" from his self-described visit to Pluto, "where no one can see you or hear what is said." The book is currently into its third printing and garnering letters and emails from around the world.

"While I have the facility to do so, I want to communicate to others, to those who will face this demon someday and those who love them, that with the proper medical direction, life strategies, faith, and humor, one can prevail," he says.

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Here's what life is really like with a disease that totally upends it, in an excerpt from On Pluto below.

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"There's not going to be any pity party, and I'll make sure of that," Pat Summit, the legendary coach of the Tennessee women's basketball team, told the Knoxville News Sentinel after announcing her diagnosis of early-onset Alzheimer's. "Obviously, I realize I may have some limitations with this condition, since there will be some good days and some bad days."

And so it is with chronic illness, good days and bad days. You get knocked down, you get back up. Again and again. You find a way to win, whether on the playing field, on the job, in the home, or in a fight against cancer, heart disease, AIDS, Parkinson's, Autism, depression, diabetes, dementia, or any number of vile illnesses. Lying down in football, as it is in wrestling, is a position of defeat. That's not a good place for any of us.

My place today is with the disease early-onset Alzheimer's; it's a death in slow motion. Alzheimer's and its predecessor, hardening of the arteries, stole my maternal grandfather, then my mother. And now it's coming for me.

The most disturbing symptoms for me are the visual misperceptions—seeing, hearing, smelling, tasting, and feeling things that aren't there, as my mother once did. There was a time in Boston, for example, after a late business meeting, when I retrieved my car on the third floor of a parking garage near Boston City Hall, only to find that a thick, grated-metal wall had been pulled down to block my path. I feared I was locked in for the night. Walking toward the obstruction, the wall suddenly disappeared. It wasn't real.

Then there are those insect-like creatures that crawl along the ceiling regularly at different times of day, sometimes in a platoon, that turn at 90-degree angles, then inch a third of the way down the wall before floating toward me. I brush them away, almost in amusement, knowing now that they are not real, yet fearful of the cognitive decline.

I still have feeling on the bottoms of my feet for walking and running, yet no feeling on the tops of my feet. I have feeling on the bottoms of my fingers for keyboarding, but little or no feeling on the tops of my hands, often at times up to my elbows. My brain may be conserving power, I've been advised—sort of a cerebral brownout, akin to a drop in voltage in big cities to prevent electrical blackout, intentional or otherwise.

My brain was once a file cabinet, carefully arranged in categories, but at night as I sleep, it's as if someone has ransacked the files, dumping everything onto a cluttered floor. Before I get out of bed each morning, I have to pick up the "files" and arrange them in the correct order—envelopes of awareness, reality, family, work, and other elements in my life. Then it's off for coffee.

There have been mornings when I haven't recognized my wife lying next to me. I knew I was supposed to be in the bed with this attractive woman, but I wasn't sure who she was. She looked familiar, but I had no understanding for several minutes of my relationship with her, a woman I have slept with for 37 years. It is disturbing; I never let on to her about the shame of it.

Now I have a repertoire of banter always at the ready—on sports, politics, and religion for those who want to go deep. It's a defense mechanism until I find my bearings. I play a game with myself, upping the stakes every day: How long can I pull this off without someone noticing?

I've come now to understand that Alzheimer's is not about the past—the successes, the accolades, the accomplishments. They offer only context. Alzheimer's is about the present, and the struggle, the scrappy brawl, the fight to live with a disease. It's being in the present, in the relationships, the experiences. It's the courage to live in the soul.

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