The findings suggest that there is a common pathway between inherited Alzheimer’s and late-onset Alzheimer’s, said Dr. Randall Bateman of Washington University School of Medicine in St. Louis, who is an associate director of the study.

“That is the pathway we want to treat. If we can interfere with that, we can hopefully prevent Alzheimer’s disease,” he said.

Drug companies are being selected to test their experimental medicines on these study volunteers because if they have the gene, they are certain to get Alzheimer’s.

“It’s a huge opportunity,” said Dr. Rachel Schindler, an Alzheimer’s disease expert at Pfizer Inc, which is developing the drug bapineuzumab with Johnson & Johnson, which is now in late-stage clinical trials.

“It’s a window into how early we really can detect the changes related to Alzheimer’s disease. Without that window, you’d have to study hundreds of people over a long period of time because only a few of them would end up developing the disease,” Schindler said.

If scientists can understand the disease, they can apply much of what they learn to late-onset Alzheimer’s, she said.

People in the study are eager to participate in the drug trials, Bateman said. “They are desperate to have treatments for their families.”

Marty Reiswig, a 32-year-old minister living near Denver, found out about the study from his brother Matt. Matt told Marty that he had to read a book about the family’s disease by Gary Reiswig - their father’s cousin.

After reading the book, “The Thousand Mile Stare: One Family’s Journey through the Struggle and Science of Alzheimer’s,” the brothers agreed that their family would make perfect “lab rats,” Marty said.

That is because people in his family, unlike most people who get Alzheimer’s, know it’s coming, he said.

Marty undergoes annual lumbar punctures to have his spinal fluid checked for levels of amyloid and tau - the proteins that help predict Alzheimer’s progression - and because he has no symptoms, he has a battery of memory tests every three years.

“Because I am a child of an affected early onset Alzheimer’s person, they want to study my mental health progress,” Marty said.

Marty’s and Matt’s father Lawrence is also part of the study.

Marty says he relishes his visits with Dr. Bateman, and loves to pepper him with questions about the study.

In one recent visit, he got some good news.

“I was lying in bed with lumbar puncture in my back, talking to Dr. Bateman,” Marty recalled. “He said, ‘I think some time in the next 12 months, there is a very good possibility we might be doing clinical trials with you to find drugs to prevent the onset of Alzheimer’s.’”

Marty said he lay in the hospital bed and wept.

“My dad was across from me in the hospital room and we had to control ourselves. That this terrible thing could possibly sort of vanish… that was just a huge relief for us.”