"This is a powerful study and a step forward for our understanding of Alzheimer's disease," said neurologist Dr. Richard Isaacson, who heads the Alzheimer's Prevention Clinic at Weill Cornell Medicine.
"Finding these new genes allows doctors one day to target these genes with therapeutic interventions," said Isaacson, who was not involved in the study. "It also gives us a better insight into the possible causes of Alzheimer's disease."
The findings of the study will not change anyone's daily life or medical practice any time soon, "said Heather Snyder, senior director of medical and scientific operations at the Alzheimer's Association, who also did not participate in the new study.
"Having said that, they give us potentially insightful insights into the bodily processes that can cause or interact with changes in Alzheimer's disease and other dementias," added Snyder.
Raising the numbers to 94,000, the new study added 30% more data for the analysis, allowing researchers to check 20 previously found genes and add four.
As the new genes – IQCK, ACE, ADAMTS1 and WWOX – along with a gene previously discovered called ADAM10, affect the development of Alzheimer's disease is under investigation. But once their specific functions are understood and examined, researchers say they will be able to start developing potential drug targets.
"Alzheimer's disease is a complex disease. It's not like Huntington's or Parkinson's disease, where a gene is altered and you have the disease," said senior author Dr. Margaret Pericak-Vance, director of the Hussman Institute.
"With Alzheimer's disease, there are several genes acting together," Pericak-Vances said. "We were trying to find out the very rare genetic variants that could contribute to Alzheimer's disease, and we could not do that before. the sample size to do this. "
"We saw amaloid early, but it had not been verified in one [genome-wide association study]"Said Tanzi. So, I think one thing that's exciting is that it brings us back to the amyloid as a great player.
"I should also say that we are also seeing that the other major pathway, other than the amyloid, is innate immunity," Tanzi said. "In this study, we are seeing even more innate immune genes that affect susceptibility to neuroinflammation."
Susceptibility to neuroinflammation is critical, Tanzi says, "because at the end of the day, plaques and tangles can set the stage, but it is neuroinflammation that kills enough neurons to get to dementia."
Now, with more than a dozen genetic targets on how immunity binds to Alzheimer's disease, Tanzi said, "it should really facilitate a new drug discovery."
The increase in sample size allowed researchers to discover "gene centers" that could affect the development of Alzheimer's disease. "And some of these genes have the potential to have more than one function," said lead author Brian Kunkle, associate scientist at the Hussman Institute.
"They may be increasing risks through different pathways of disease," said Kunkle. "The prediction of risk and treatment for each individual will depend on the type of changes a person has in each of these 25 genes or other biomarkers."
Isaacson said the ongoing work could lead to "precision medicine at its best".
"A person can take many different roads to Alzheimer's disease," Isaacson said. "If we can find out on what road a person is through identifying certain genes, we can target specific interventions that may work preferentially for that particular person."
As for when this can occur, Kunkle is cautiously optimistic.
"It's hard to say if this will help someone who has Alzheimer's now," he said. "Hopefully, we will have treatments developed for members of your family who may have those genes that put them at risk."