Study Suggests Genetics as a Cause, Not Just a Risk, for Some Alzheimer's (nytimes.com) 12
Pam Belluck reports via the New York Times: Scientists are proposing a new way of understanding the genetics of Alzheimer's that would mean that up to a fifth of patients would be considered to have a genetically caused form of the disease. Currently, the vast majority of Alzheimer's cases do not have a clearly identified cause. The new designation, proposed in a study published Monday, could broaden the scope of efforts to develop treatments, including gene therapy, and affect the design of clinical trials. It could also mean that hundreds of thousands of people in the United States alone could, if they chose, receive a diagnosis of Alzheimer's before developing any symptoms of cognitive decline, although there currently are no treatments for people at that stage. The new classification would make this type of Alzheimer's one of the most common genetic disorders in the world, medical experts said.
"This reconceptualization that we're proposing affects not a small minority of people," said Dr. Juan Fortea, an author of the study and the director of the Sant Pau Memory Unit in Barcelona, Spain. "Sometimes we say that we don't know the cause of Alzheimer's disease," but, he said, this would mean that about 15 to 20 percent of cases "can be tracked back to a cause, and the cause is in the genes." The idea involves a gene variant called APOE4. Scientists have long known that inheriting one copy of the variant increases the risk of developing Alzheimer's, and that people with two copies, inherited from each parent, have vastly increased risk.
The new study, published in the journal Nature Medicine, analyzed data from over 500 people with two copies of APOE4, a significantly larger pool than in previous studies. The researchers found that almost all of those patients developed the biological pathology of Alzheimer's, and the authors say that two copies of APOE4 should now be considered a cause of Alzheimer's -- not simply a risk factor. The patients also developed Alzheimer's pathology relatively young, the study found. By age 55, over 95 percent had biological markers associated with the disease. By 65, almost all had abnormal levels of a protein called amyloid that forms plaques in the brain, a hallmark of Alzheimer's. And many started developing symptoms of cognitive decline at age 65, younger than most people without the APOE4 variant.
"This reconceptualization that we're proposing affects not a small minority of people," said Dr. Juan Fortea, an author of the study and the director of the Sant Pau Memory Unit in Barcelona, Spain. "Sometimes we say that we don't know the cause of Alzheimer's disease," but, he said, this would mean that about 15 to 20 percent of cases "can be tracked back to a cause, and the cause is in the genes." The idea involves a gene variant called APOE4. Scientists have long known that inheriting one copy of the variant increases the risk of developing Alzheimer's, and that people with two copies, inherited from each parent, have vastly increased risk.
The new study, published in the journal Nature Medicine, analyzed data from over 500 people with two copies of APOE4, a significantly larger pool than in previous studies. The researchers found that almost all of those patients developed the biological pathology of Alzheimer's, and the authors say that two copies of APOE4 should now be considered a cause of Alzheimer's -- not simply a risk factor. The patients also developed Alzheimer's pathology relatively young, the study found. By age 55, over 95 percent had biological markers associated with the disease. By 65, almost all had abnormal levels of a protein called amyloid that forms plaques in the brain, a hallmark of Alzheimer's. And many started developing symptoms of cognitive decline at age 65, younger than most people without the APOE4 variant.
huh? (Score:2)
This was already common knowledge. In fact I stated it here and people told me I was wrong: https://science.slashdot.org/c... [slashdot.org]
Executive summary (Score:3)
If you have genes, you're at risk for Alzheimer's.
Re:Executive summary (Score:5, Informative)
If you have particular gene variants. In fact there are some gene variants that virtually guarantee you won't get Alzheimers.
Re: (Score:2)
Actually, I think the gp intended his comment as humor.
Re: (Score:3)
Indeed he did!
Re: (Score:2)
Indeed he did!
And in all humor, there is a bit of truth.
I'm inclined to agree with you. So many wish to believe we are on the cusp of immortality - we've been on the cusp of immortality since at least the 1970s. It's like the longevity version of fusion power.
If we want to counter the 20 percent of Alzheimer's patients are now known to have a genetic cause, well, that means we don't for 80 percent of them.
And what do we do with this precious kernel of truth on the path to humanity freeing itself from the shackle
Mechanism (Score:2)
The researchers found that almost all of those patients developed the biological pathology of Alzheimer's, and the authors say that two copies of APOE4 should now be considered a cause of Alzheimer's -- not simply a risk factor.
So they've found the mechanism, right?
Re: (Score:2)
Try "a mechanism". That only explains about 20% of the cases.
Re: (Score:2)
Try "a mechanism". That only explains about 20% of the cases.
Right - 80 percent is menta incognita.
It has to have been obvious for a long time that dementia has many causes, and "Alzheimers" has been assigned to too many. And if there appears to be an epidemic, a possible reason is that more people have artificially extended their lifetime into a period where cognition is more likely to diminish.
No shit? (Score:3)
A8s isn't a singular disease (Score:2)