The disease affects a different brain protein and occurs mostly in people over 80.

When is Alzheimer’s disease not Alzheimer’s disease? It’s a riddle that finally has an answer. 

Researchers recently pinpointed another form of cognitive decline with many of the same hallmarks as Alzheimer’s, but which actually involves different brain processes. This newly discovered dementia may partly explain why some people haven’t been helped by current Alzheimer’s drugs or why some drugs being tested haven’t been as successful as scientists have hoped.

The disorder, dubbed “LATE,” stands for limbic-predominate age-related TDP-43 encephalopathy. Like Alzheimer’s, LATE affects short-term memory and causes cognitive impairment. It also shares some of the same disease traits as frontotemporal dementia. However, LATE affects a different brain protein than those associated with Alzheimer’s and mostly occurs in people older than 80, according to a working paper developed by researchers at the University of Kentucky Sanders-Brown Center on Aging in Lexington for the National Institutes of Health. It was published in the journal BRAIN.

Figuring out whether someone has Alzheimer’s or LATE can be difficult. There’s no blood test yet for LATE; it can only be diagnosed with certainty during an autopsy. For now, determining whether someone may have the LATE form of dementia is more a process of elimination than a definitive diagnosis, after testing eliminates conditions like Alzheimer’s or Parkinson’s.

We found a large proportion of people during life who had some of the symptoms of Alzheimer’s disease didn’t have the biomarkers of Alzheimer’s disease.
Dr. Peter Nelson, who led the University of Kentucky study.

LATE has probably affected clinical trials, because people may be getting treated for a disease they don’t have, Nelson says.

Despite the lack of diagnostic tools for LATE, this study helps explain why certain medications don’t seem to work for people who are told they have Alzheimer’s.

They may exhibit symptoms of Alzheimer’s, but underneath the hood, there’s a fairly good chance - especially in people over 80 - that maybe it’s something else.
Dr. Sami Barmada

An increasingly ageing population puts more people at risk for some type of dementia, according to the University of Kentucky report. However, many gaps exist in our understanding and diagnosis of LATE, such as identifying biomarkers or more precise brain imaging.

The lack of diagnostic tools will have a massive impact on our public health system. It’s causing so much strain, not only on patients, but on the caretakers; it’s brutal. It’s something we really need to address.
Dr. Peter Nelson, who led the University of Kentucky study.

More research funding is necessary to help define risks and features of LATE to better diagnose and eventually treat the disease in progress, Nelson says. Adding to this challenge is that LATE-type dementia can develop alongside Alzheimer’s.

We need to get more older people into clinical trials so we can develop therapies to have any hope. Having really well-trained clinicians is important, too, and there aren’t as many as are needed.
Dr. Peter Nelson



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