In July, the Miller's held a family reunion in Cape Cod. It was part vacation, part summit meeting.
"I just felt very strongly that this would be the last summer he had any kind of verbal skills, any kind of recognition of us being a family," says Sue Miller, Don's wife and primary caregiver.
Don's children, Brian and Laura, traveled from their homes in California and Alabama to Massachusetts to help plan for the future. Diagnosed at age 55, Don faces years of care.
"Whatever's happening in the body is happening so slowly you don't really have a sense of a change from one day, one month to the next," says Don.
But, as CBS News Correspondent Elizabeth Kaledin reports, Sue does.
"It's a very cruel disease," she says.
Sue is battling her own depression. The intensity of his round the clock care is exhausting and often exasperating.
"The last time I asked him to pack, he packed two pairs of underpants, a pair of shorts and about 32 pairs of socks," she says.
And now Sue is panicked that the family finances won't last. The day care center Don attends in Connecticut costs $80,000 a year full-time, so Sue is exploring less expensive options where her children live:
And as the family debates, Don waits.
"I'm waiting for somebody to come up with a cure somewhere," he says.
The situation is different for the Beckers. Ruth is much older and much more frail.
Since her husband Bob died last year, she lost 50 pounds and developed seizures, a common problem in late stage Alzheimers. Norman Relkin is one of her doctors.
"Her care needs are similar to a 2-year-old child," says Relkin.
Ruth just started visiting a day care center twice a week. Justine Butler is her caregiver and oldest friend.
"She's very happy right now, and we just enjoy being with her," says Butler.
Ruth's sons, Peter, Paul and Michael, are determined to keep her at home.
"I think everyone's in agreement; she's going to stay in this house and she's going to do the best she can," says Michael.
But home is becoming increasingly unsafe. Ruth can no longer navigate the spiral staircase to her bedroom:
For both families Alzheimer's disease involves constant rebuilding and remembering.
"The single most important thing we can do in interacting with an individual who has Alzheimer's disease is to always remember who they are, and to remember the person that they they've been throughout their lives," says Relkin.
Easier said than done when it comes to a disease that steals something from everyone it touches.