Bob Demarco, 62, spent more than eight years taking care of his mother, who had Alzheimer's disease before she passed away at age 95 in May 2012.
During this eight-year period, his chief concern as a caregiver was for his mother. But sometimes, he says, he would think of his own risk in the future.
"I'm sure I was more worried at the beginning when my mom got diagnosed," says Demarco, of Delray Beach, Fla., who is also the founder and editor of the Alzheimer's Reading Room blog. "I would describe myself as concerned more than worried."
Still, Demarco opted for the genetic testing to look for a gene known to significantly increase the risk of Alzheimer's. He tested negative for the gene.
Still, he says, "certainly my predisposition is higher than someone who doesn't have AD in their family.
"Sometimes when I forget something, the idea pops into my head."
Indeed, first-degree relatives of adults with Alzheimer's disease have a higher lifetime risk for developing the condition than those without a family history. However, there is currently little that these relatives can do that is proven to lower their risk of developing the disease later.
It is this problem that Dr. Sam Gandy, professor of Alzheimer's disease research at Mount Sinai School of Medicine, believes will be addressed sooner rather than later. And he says a new study published in the New England Journal of Medicine today may set the stage for Alzheimer's prevention studies in the near future -- studies that may have more implications for the children of patients than for the patients themselves.
The new study looked at adults who had a genetic form of Alzheimer's but had not yet displayed symptoms. Interestingly, researchers found that changes in the levels of a protein associated with Alzheimer's, called amyloid, can be detected up to 25 years before symptoms begin.
In an editorial accompanying the new study, Gandy explains why this matters.
"I think this study sets the stage for prevention studies," Gandy tells ABCNews.com.
"The only way to know how important amyloid is is to prevent it from forming altogether."
The editorial comes at a time when the potential role of amyloid in Alzheimer's is a topic of growing controversy. A number of trials for amyloid-lowering drugs failed to show any benefits in patients with mild Alzheimer's.
Gandy argues that these recent drug trials were started too late. Instead, he argues, new studies should target Alzheimer's prevention, ideally decades before patients show any signs of the disease. Hypothetically, the trials could target adults in their 40s and 50s with a family history of the disease. If a safe amyloid-lowering drug was available, first-degree relatives could potentially get a trial of the drug, and researchers could monitor these individuals to see if they developed Alzheimer's or not.
Most Alzheimer's experts contacted by ABC News agree that the new data is promising.
"In my view, the editorial is precisely on target," says Dr. Paul Aisen, director of the Alzheimer's disease cooperative study at the University of California San Diego. "This is an important message to share with the scientific community and with families affected by [Alzheimer's] who are discouraged by the disappointing results of large anti-amyloid trials conducted in individuals with dementia."
"Ultimately, to make a real impact, we have to focus on prevention," says Dr. James Galvin, professor of neurology and psychiatry at New York University Langone School of Medicine. "This means identifying markers of disease to initiate effective treatments before symptoms begin. Waiting until someone already has memory loss suggests that there is already substantial damage to vital brain systems."
Some experts, however, were more skeptical of the editorial's message. Specifically, they question whether amyloid is really the true or only culprit behind Alzheimer's -- and whether focusing on it so heavily may close the door too early on exploring other potential factors behind the disease.
"The danger is that if we rely only on the amyloid hypothesis for developing treatment, we might miss other opportunities," says Dr. Zaven Khachaturian, president of the Prevent AD 2020 Campaign.
Dr. Peter Whitehouse, professor of neurology at Case Western Reserve University School of Medicine, says recent research "should be the proverbial nail in the amyloid coffin," but that the debate will likely continue -- "because there is too much fear and false hope," he says.
Others point out that while inherited Alzheimer's may be associated with amyloid, other cases may not be. Thus, they argue, this research's potential for prevention may be less relevant to the general population.
"It is not clear that this model is the best for sporadic disease," says Dr. Mary Sano, director of Alzheimer's research at Mount Sinai School of Medicine. "There is significant evidence that, in the very old, amyloid burden can exist without symptoms."
Sano adds, "Early, or lifelong, treatment is only warranted with very safe medications, few of which exist."
If such a drug existed, "I'd be standing in line the day the drug store opened with it," says Demarco. "If I am predisposed to Alzheimer's disease, my personal goal would be to prevent it as long as possible."