On a recent flight from San Francisco back to Boston, I found myself seated between my 28-year-old daughter, Colleen, and the emergency hatch. When the attendant had asked if I could perform the duties, I shrugged and simply said I was afraid of heights. I forgot about the confusion part. I forgot why doctors don't let me travel alone any more. Alzheimer's will do that.

Somewhere over Chicago, I had to go to the bathroom. My mind told me the bathroom door was immediately to my right — all I had to do was to pull on the lever — so I grabbed for it. It took Colleen screaming for me to realize my hand was on the emergency exit door. The crew later told me never to sit in an exit row again.

My life has become a race for survival against Alzheimer's, and I'm not the only one. More than 5 million Americans suffer from this demon of a disease, a number expected to double in the next 20 years as my fellow baby boomers reach the age of its onset. Treating Alzheimer's in the United States now costs more than $200 billion a year. By 2050, that will surpass $1 trillion.

So as a longtime investigative journalist, I've been chronicling my own experience with the disease so others know what to expect.

Boomers and our families will soon find out that Alzheimer's is not just a disease of the elderly: Experts say it can take 20 to 25 years to run its serpentine course. The brain pathology, doctors observe, can begin at 40. I know the frontline well: Alzheimer's stole my maternal grandfather, my mother and my paternal uncle. And before my father's death, he also was diagnosed with dementia.

Now it's my turn.

In 2009, at age 59, I was diagnosed with early onset Alzheimer's. A battery of clinical tests, brain scans and a SPECT scan confirmed the diagnosis, which doctors say was accelerated by two serious head traumas that “unmasked a disease in the making.” I also carry the Alzheimer's marker gene APOE-4.

The finding came two weeks after I had been diagnosed with prostate cancer, which, after consulting with my family and my doctors, I've decided not to treat. My plan is for cancer to kill me before my Alzheimer's symptoms get too awful. I don't want to take my wife and children to that end place of Alzheimer's. I've been there already with family.

But after a brief pity party, I pulled myself up to deal with Alzheimer's. I reverted to mental muscle memory and began to report on my demise, detailing 1,000 pages of notes that became “On Pluto: Inside the Mind of Alzheimer's.” My book is a blueprint of strategies, faith and humor, a day-to-day focus on living with Alzheimer's, not dying of it, a hope that all is not lost when it appears to be.

For baby boomers, I feel like the canary in the coal mine while scientists search for a cure. I fear the day when I put my fingers on the keyboard and don't know how to write anymore; that's the day I will give up, heading out, as I put it in the book, to the desolation of Pluto.

Mornings for me are always the same: in disarray. At first light I must focus on the basic questions: the who, what, where, when, why and how of life. I do so out of instinct, but there's always the depression, fear and angst to maneuver. And that's just on the way to the bathroom, where, on doctors' advice, I've begun labeling the toothpaste, liquid soap and rubbing alcohol. I have attempted often to brush my teeth with liquid soap, and on two occasions gargled briefly with rubbing alcohol.

My mind used to be my best friend, but now I see no chance for reconciliation. Doctors say that I'm working off a “cognitive reserve,” a backup tank of inherited intellect, but they warn that the tank will go dry soon, as it did with my mother.

Daily medications serve to slow down the progression of the disease and to help control the rage on days when 60 percent of my short-term memory is gone in 30 seconds, days when I hurl the phone across the room because in the moment I don't remember how to dial. Or when I smash the lawn sprinkler against an oak tree in the backyard because I can't recall how it works, or when I push open the flaming-hot glass door to the wood stove in the family room barehanded to stoke the fire because my mind in the moment told me it was a good idea, resulting in a second-degree burn. Or simply when I cry privately, the tears of a little boy, because I fear that I'm alone, nobody cares and the innings are beginning to fade.

Years ago, I thought I was Clark Kent, Superman, an award-winning journalist who feared nothing. But lately, I feel more like a baffled Jimmy Olsen. And on days of muddle, more like Mr. Magoo, the wispy cartoon character who couldn't see straight, whose poor vision was exacerbated by his stubborn refusal to acknowledge a problem.

The Irish like to say: Never get mad, get even!

By documenting it, I'm getting even with Alzheimer's. But I cannot do it alone, and I do not know how much time I have left before the lights go out. If we are going to win this fight, we need to grapple with the scope of the problem and try harder to cure it. Not for me — the train has already left — but for my children, and for you and your children and for my whole generation and their families and loved ones, who will face this prowling demon soon enough.