Early and LATE Dementia

From the day Jim was diagnosed with an Alzheimer’s type of dementia, I researched the disease through all sources possible. I used the Internet, books, pamphlets, watched TV specials, and talked to some of the top researchers in the country.

My conclusion was that early onset dementia and dementia in older people seemed to be two different diseases. It seemed obvious to me that early onset progressed much faster. That didn’t seem logical since younger people generally started out with healthier bodies. Yet, I found that the median life expectancy of younger-onset Alzheimer’s was six to eight years. For those diagnosed with Alzheimer’s later in life, the average life expectancy was ten years, but could be as long as twenty years or more.

Now, researchers have discovered that some seniors who had been diagnosed with Alzheimer’s actually had a type of dementia identified as LATE (Limbic-predominant Age-related TDP-43 Encephalopathy).

Although LATE mimics Alzheimer’s disease, the proteins beta-amyloid plaques and tau tangles that are the hallmark signs of Alzheimer’s do not cause the dementia. LATE is caused by deposits of the protein TDP-43 (transactive response DNA binding protein of 43 kDa) in the brain.

The report identifying LATE was published in the April 30, 2019, issue of the journal Brain. This is a major breakthrough in how researchers will look at dementia in older adults. LATE is believed to affect 25% of seniors with dementia who are eighty-five years or older. 

At the Alzheimer’s Advocacy Forum in Washington, D.C., advocates often receive reports from Richard Hodes, M.D. director of the National Institute on Aging (NIA), part of the National Institutes of Health (NIH).  This latest development in the study of dementia can be seen as an opportunity. Dr. Hodes said, “The guidance provided in this report, including the definition of LATE, is a crucial step toward increasing awareness and advancing research for both this disease and Alzheimer’s as well.”

Abnormal TDP-3 had been previously identified in ALS (amyotrophic lateral sclerosis) also known as Lou Gehrig’s disease. TDP-3 has been found in FTLD (frontotemporal lobar degeneration). FTLD is a group of disorders that affects the frontal and/or temporal areas of the brain. FTD (frontotemporal degeneration) is a rare disease more commonly found in those younger than sixty years of age.

The progression of LATE is slower than Alzheimer’s disease. When LATE and Alzheimer’s disease are both present, the disease progresses more rapidly than either disease does alone.

The information from this study came from brain autopsy reports. We had an autopsy on Jim’s brain for the simple reason that I wanted to know what disease he had and whether it was hereditary. Of several terms used in his autopsy, I recognized a few: neurodegenerative disorder, incidental Lewy body, frontotemporal atrophy, swollen neurons, and tau positive glial inclusions. The cover letter said that Jim showed no signs of Alzheimer’s. He had corticobasal degeneration, a rare (non-hereditary) disease, and one I had never heard of.

Treatments targeting beta amyloid plaques would not be effective in a disease that does not have the plaques. Rare diseases do not have the funding of diseases that are more common. Funding Alzheimer’s research is our greatest hope of finding effective treatment for other types of dementia.

Sources:

https://www.nia.nih.gov/news/guidelines-proposed-newly-defined-alzheimers-brain-disorder

https://www.sciencedaily.com/releases/2019/04/190430121800.htm

Copyright © June 2019 by L.S. Fisher

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