The disease, called LATE, may often mirror the symptoms of Alzheimer's disease, although it affects the brain differently and develops more slowly than Alzheimer's. Doctors say the two are often found together, and in those cases can lead to a steeper cognitive decline than either one.
In developing its report, the international team of authors hopes to spur research – and, perhaps, one day , according to the paper.
"We are really overhauling the concept of what is dementia, and it's just that, "said lead author Dr. Peter Nelson, director of neuropathology at the University of Kentucky Medical Center.
"Sandra Weintraub, a professor of psychiatry, behavioral sciences and neurology at the Northwestern University of Feinberg School of Medicine, said that there is no one single disease that causes all forms of dementia.
Weintraub said that researchers have been well aware of the "heterogeneity of dementia," but figuring out precisely why each type may look so different has been a challenge. Why do some people lose memory first while others lose language or have personality changes? Experts say this heterogeneity has a complicated dementia research, including Alzheimer's, because it has not always been clear what the root cause was ̵
What is it?
The acronym LATE stands for limbic-dominant age-related TDP-43 encephalopathy. "These age-related dementia diseases are often associated with proteinaceous glop," Nelson said. "This age-related dementia diseases are often associated with proteinaceous glop," said Nelson. "But different proteins can contribute to the glop."
In Alzheimer's, you'll find one set of glops. In Lewy body dementia, another glop.
And in LATE, the glop is a protein called TDP-43. Doctors are not sure why the protein is found in a modified, misfolded form in a disease like LATE.
"This is What are the individual vulnerabilities that cause the protein to go to specific brain regions? " she said. "More than a decade ago, doctors first linked the TDP protein to amyotrophic lateral sclerosis, otherwise known as ALS or Lou Gehrig's disease. It was also linked to another type of dementia, called frontotemporal lobar degeneration.
LATE is a disease that is 100 times more common than any of those, and no one knows about it, "said Nelson.
The new paper estimates , based on autopsy studies, that between 20 and 50% of people over 80 will have brain changes associated with LATE. And that prevalence increases with age.
Experts say nailing down these numbers – as well as finding better ways to detect and research the disease – is what they hope will come out of consensus statements like the new paper, which gives scientists a common language to discuss it, according to Nelson.
"People have, in their own separate bailiwicks, found different parts of the elephant," he said. "But this is the first place where everybody gets together and says," This is the whole elephant. " "
What this could mean for Alzheimer's
The new guidelines could have an impact on Alzheimer's research, as well. For one, experts say some high-profile drug trials may have suffered as a result of some patients having unidentified LATE – and thus not responding to treatment.
In Nelson said that "the clinical trial was a failure for Alzheimer's disease," but Nelson's colleagues recently saw that firsthand: a patient, now deceased, who was part of a Alzheimer's drug trial but developed dementia anyway.
It turns out he did not have Alzheimer's disease. He was late. "
"I" "I think it will play some part, but maybe not so much as one might think at first," said Silverberg, who co-chaired the working group that led to the new paper.
Advances in testing have already shown that some patients in these trials lacked "the telltale signs of Alzheimer's," she said.
In some cases, perhaps it was LATE – "and it is certainly possible that there are other, as yet undiscovered, the pathologies that people may have, "she added.
" We could go back and screen all the people who had failed their Alzheimer's disease therapies, "Nelson said. "But what we really need to do is go forward and try to get these people out of the Alzheimer's clinical trials – and instead get them into their own clinical trials."
Silverberg describes the new paper as a "roadmap" for research that could change as we come to discover more about the disease. She added: "It's probably going to take years and research participants to help us understand all of that," she said.