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According to the Alzheimer Society of Canada, there are 25,000 new cases of Alzheimer’s—a progressive brain disease marked by problems with memory and thinking that interfere with daily life—diagnosed every year. Now new research suggests some of these people—especially those aged 85 and older—may actually have a newly coined form of dementia known as LATE: limbic-predominant age-related TDP-43 encephalopathy. The acronym is apt since the condition tends to strike people later in life than Alzheimer’s.
“Approximately one in three of all persons over age 85 diagnosed with Alzheimer’s may actually have LATE,” says study author Peter Nelson, MD, PhD, a professor at the University of Kentucky in Lexington.
The new report, which appears in the journal Brain, is based on a National Institute on Aging (NIA) project on LATE, and it included researchers from more than 20 institutions in six countries.
Alzheimer’s versus LATE
While Alzheimer’s disease is the most common type of dementia, it’s far from the only type. LATE seems to be the most similar to Alzheimer’s in terms of symptoms, namely memory loss and confusion, but there are some important distinctions. (If you have these types of dreams, you could be at risk for dementia.)
For starters, LATE tends to hit people aged 85 and older, while Alzheimer’s often starts around age 65 and up. What’s more, LATE tends to progress at a slower pace than Alzheimer’s—unless the two diseases travel together, in which case there is a more rapid decline.
Alzheimer’s can have a genetic link, but LATE is not hereditary, says Howard Fillit, MD, founding Executive Director and Chief Science Officer of the Alzheimer’s Drug Discovery Foundation.
Like Alzheimer’s, LATE can only be definitively diagnosed after death during an autopsy of the brain, but the brains of people with LATE look a whole lot different than those of people with Alzheimer’s. “With LATE, the brain can look quite devastated in the region that serves to consolidate short-term memory called the hippocampus,” Dr. Nelson says. There’s also an abundance of a toxic protein called TDP-43 in the brains of people with LATE, which suggests a different cause than Alzheimer’s.
The tell-tale signs of Alzheimer’s in the brain include tangles of a protein called tau along with plaques of amyloid-beta, explains Julie A. Schneider, MD, MS, The Deborah R. And Edgar D. Jannotta Presidential Professor of Pathology and Neurological Sciences Associate Director, Rush Alzheimer’s Disease Center, Rush University Medical Center. Alzheimer’s damage starts in the hippocampus but eventually attacks other areas of the brain.
LATE: What’s in a name?
“Recent research and clinical trials in Alzheimer’s disease have taught us two things: First, not all of the people we thought had Alzheimer’s have it; second, it is very important to understand the other contributors to dementia,” says Nina Silverberg, PhD, director of the Alzheimer’s Disease Centers Program at the NIA, in a news release. (Learn the 50 habits that reduce your dementia risk.)
Dr. Nelson agrees: “A growing awareness of non-Alzheimer’s diseases that underlie the clinical syndrome of dementia will assist in both clinical trials for Alzheimer’s, and also for the non-Alzheimer’s dementias such as LATE,” he says. “I hope that we can now get on to better tailoring the right therapeutic strategies to the right groups of individuals.”
Time is of the essence, Dr. Fillit adds. “The old-old or individuals aged 85 and older are the fastest growing segment of our population.”
Can LATE be treated?
Like Alzheimer’s the disease is incurable. Doctors can and do use some of the same drugs to ease symptoms of LATE as they do for Alzheimer’s, but in the future, there may be targeted drugs that work better for each type of dementia.
When doctors treat cancer today, they analyze a tumour’s genetic makeup and pair it with therapies that are more likely to be effective. Such “precision medicine” may one day play a role in treating dementia. “We hope to identify subtypes of dementia with cheap and non-invasive blood tests and then have tailored treatments,” Dr. Fillit says. Because of the new report, “we can now say, it’s probably LATE, and we know about TDP-43, which ultimately gives us a drug target.”
Next, check out the early signs of Alzheimer’s every adult should know.