I recently visited my daughter and her family in Napa, CA. On the train trip there, I met Kalju (pronounced "Kal-you"), a seventy-nine-year-old immigrant from Estonia who regaled me with stories of his past.

Kalju was seventeen when, early in World War II, the Soviet army occupied Estonia. He was about to be shipped off to Siberia when his Soviet employer notified authorities that he'd been servicing army trucks and was therefore vital to the war effort. Shortly after, when the Germans drove the Soviets out and occupied Estonia, Kalju was sent to a work camp in southern Germany.

After the war, he immigrated to Winnipeg, Manitoba, where he worked as a laborer. He was transferred for a while to Churchill in the far north on Hudson Bay. He worked his way through high school until he immigrated to Chicago, where he was educated as a social worker and ultimately worked with African-American children in a Chicago ghetto for twenty years.

During the 1968 riots, young African American men rolled his car over one-and-a-half times and left him upside down in the car; on another occasion he was almost hammered to death until others intervened.

He was accompanied on the train by Judy, a 46-year-old author, and her daughter. Judy had known Kalju for decades and recently decided to write his biography. They've become close friends. Judy and her daughter accompany him in his frequent travels, in part because they enjoy his company, in part because he needs their help.

I had talked with Kalju for an hour before I recognized his dementia. We'd been on the train for over 24 hours, yet he asked Judy for the directions to the bathroom, which was on the first level of the same car. A few minutes afterwards, he came back to ask directions again.

I later talked with Judy. Kalju's symptoms, she said, can be pronounced but are extremely variable. He recognizes his poor memory and his reliance on Judy and her daughter for orientation, yet he denies any general cognitive impairment.

When I mentioned my Alzheimer's to him, he said he was glad he didn't have anything like that: His head simply had too much information, and there wasn't room for anything new.

Shortly after meeting Kalju and deciding to write his biography, Judy realized that, while he told wonderful stories, he repeated them frequently. She's now heard each of his few stories many times and realized she can't write an autobiography with so little material.

Kalju can be quite disoriented indoors, she tells me. In a hotel room, for instance, Kalju has to ask every day where the bathroom is. Outdoors, however, he can go for long walks, even in unfamiliar environments, and never get lost.

Judy has witnessed personality changes too, like when Kalju explodes in anger for no apparent reason. Often he apologizes but may later deny that the incident happened.

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His judgment is sometimes impaired. They were once on a city bus riding through a poor, inner-city ghetto. Although the bus was full of African Americans, Kalju began talking loudly about the two times in Chicago he'd been attacked by young black men.

She has also noticed that, in the moment, he'll recognize his poor memory, his disorientation and his need for assistance, but, when the moment is past, he doesn't seem to remember these episodes of confusion, adamantly denying any impairment.

As I discovered when I engaged him in conversations, his impairment is not immediately evident and he can be quite lucid: I might never have realized he had dementia had I not witnessed his repeated asking for directions to the same place.

He doesn't fit into the stereotype of Alzheimer's. He is able to maintain good relationships. He can go on long walks outdoors without getting lost or disoriented. His life appears full.

He helped me to see that life with Alzheimer's – even when symptoms are becoming more evident – does not have to lead to early isolation. It's comforting.

David’s story, along with the journeys of two other families coping with dementia, was chronicled in "Fade to Blank: Life Inside Alzheimer's" an in-depth examination of life during each stage of the disease.