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Understanding dementia
A new type of the disease was recently found

By Melissa Erickson

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If someone you know suffers from memory loss, what would you say about his or her illness? Is it Alzheimer’s or dementia? When is Alzheimer’s not Alzheimer’s?

It’s a common misconception, said Dr. Peter Nelson, professor of pathology at the Sanders-Brown Center on Aging, University of Kentucky: Using the terms “Alzheimer’s disease” and “dementia” interchangeably is no longer generally accepted practice. Medical advances and recent research have led to a rising appreciation that a variety of diseases and disease processes contribute to dementia.

Previously, many people enrolled in clinical trials for Alzheimer’s drugs did not likely have amyloid — the sticky substance that gums up neurons and interferes with thinking — in their brains, according to Dr. Nina Silverberg, director of the Alzheimer’s Disease Centers Program at the National Institute on Aging. Research has shown that not all people who were thought to have Alzheimer’s have it, which has led to further study to understand the other contributors to dementia, Silverberg said.

Consider the common cold, which can be caused by more than 200 different kinds of viruses, Nelson said: “So why would we think there is just one cause of dementia?”

After a long process with an international, multidisciplinary team co-chaired by Nelson and Silverberg, a newly named dementia was announced April 30. The research was published in the journal Brain.

Called LATE, this form of dementia tends to appear in the oldest sufferers. It may seem the same as Alzheimer’s to the layperson, but the disease inside the brain looks very different, Nelson said.

“LATE is a neurodegenerative disease, and the connotation of the acronym is that it affects people at the ‘latest’ portion of the human aging spectrum,” he said. “It differs from Alzheimer’s in terms of the findings at autopsy — both have gloppy proteins that kill brain cells, but the gloppy proteins differ from disease to disease.”

Like Alzheimer’s disease, LATE affects multiple areas of cognition, ultimately impairing activities of daily life, but it appears that LATE progresses more gradually than Alzheimer’s. When LATE is combined with Alzheimer’s, which is common, the combination appears to cause a more rapid decline than either would alone.

The discovery is a push forward in dementia research.

“It’s part of an enormous problem — dementia — that has great emotional and social costs, as well as financial — $200 billion per year in America alone,” Nelson said. “It’s time for a collective decision to focus on beating these horrible diseases, and grappling with the complexity of the problem is a necessary step in accomplishing that goal.”

It’s crucial to stop thinking of dementia as a one-size-fits-all disease.

“We are shifting toward being able to treat the diseases that underlie dementia. As a necessary precondition to that, we need to be able to characterize the subtypes of diseases that contribute to dementia,” Nelson said.

The next steps are clinical trials and further research into the “how” and “why” of how LATE responds to different treatments, which can help develop disease-specific drugs that target the right patients, Nelson said.