Dick Purdy was in his mid-70s when he was diagnosed with Alzheimer's disease. Now 82, the former surgeon has steadily declined, but at times his insights still seem sharp.
"It just never occurred to me someday I would be a patient," he said, sitting in his living room in Connecticut.
For Purdy's wife, Gloria, the goal now is to keep him living at home as normally as possible and to get him enrolled in a clinical drug trial. Even if the treatment doesn't help his memory, she says, taking part in a study gives them both a sense of purpose.
"We've been part of the medical community all our adult lives," the 74-year-old retired nurse said. "We are not going to be part of the cure, clearly—at least we can participate in the work that's being done."
(Read more: Aging baby boomers may find long-term care elusive)
After more than two decades of research, a treatment that slows or actually reverses the progression of Alzheimer's has proved elusive, in part because researchers still have not pinpointed its cause.
"The scientific community really doesn't understand the disease completely," said Morningstar pharmaceutical analyst Damien Conover. "It's an area where the science still needs to evolve."
Big need, big opportunity, big risk
The need for an effective treatment is massive and growing. Dementia affects 5 million-plus people in the U.S. and over 35 million worldwide, according to Alzheimer's Disease International. With the global population aging, those numbers are expected to triple by 2050.