Alzheimer's is not always Alzheimer's

Unknown dementia form leads to similar symptoms but has other causes

Memory and other symptoms typical of Alzheimer's are not always due to this form of dementia. © tampastra / istock
Read out

But no Alzheimer's? Many alleged Alzheimer's patients could be unrecognized suffering from another form of dementia. Because as researchers now report, especially among the very old people a kind of pseudo-Alzheimer's is widespread. Although this condition manifests itself through similar symptoms, it is accompanied by other changes in the brain - and may need to be treated differently.

Alzheimer's is one of the most common dementias in old age - but not the only one. It is true that suffering in linguistic usage is often equated with the term "dementia". Increasingly, however, it turns out that many supposed cases of Alzheimer's are actually due to another cause.

"Science has discovered in recent years that a large number of patients with typical Alzheimer's symptoms lack the characteristic beta-amyloid plaques and misfolded tau proteins in the brain, " said Nina Silverberg of the US National Institute on Aging and her colleagues.

Misfolded TDP-43 proteins

Instead, misfolded TDP-43 proteins seem to be involved in these cognitive deficits-substances that normally regulate the expression of genes in the brain and other tissues, and have been known to play a role in rare-disease ALS. To understand this form of dementia and better distinguish it from real Alzheimer's disease in the future, the researchers have now devoted themselves to the disease.

As they report, pseudo-Alzheimer's seems to affect mostly very elderly people. In the early stage, the misfolded TDP-43 proteins initially show up in the amygdala, later also the hippocampus and other brain areas important for learning and memory are affected. TDP-43 pathology, according to the team, is often associated with a marked shrinking of the hippocampus region, as is typical of Alzheimer's disease. display

As common as Alzheimer's

The dementia form designated by the scientists with the abbreviation "LATE" seems to affect the everyday life of those concerned similar to Alzheimer's. However, there are signs that the disease is progressing at a slower rate than its well-known counterpart.

Silverberg and her colleagues assume that LATE in old population groups is similar to Alzheimer's: "Research indicates that about 25 percent of individuals have over 85 enough misfolded TDP cells. 43 in their brains to noticeably affect memory and thinking skills, "they explain. In addition, a combination of Alzheimer's and LATE is not uncommon.

"Wrong" subjects?

Researchers are pleading to explore pseudo-Alzheimer's more intensively in the future and, among other things, to develop biomarkers for diagnosis. Alzheimer's research could ultimately benefit from this: "Many patients who have previously participated in clinical trials for Alzheimer's research have probably not had Alzheimer's, " says Silverberg.

"This could help explain why many advanced drugs failed in clinical trials, " adds co-author Peter Nelson of the University of Kentucky at Lexington. "LATE probably addresses other therapies than Alzheimer's disease."

"The definition of LATE and the recommendations in the report that has just been published are an important step in strengthening awareness of this dementia and furthering its research and research into Alzheimer's disease, " concludes t the director of the National Institute on Aging, Richard Hodes. (Brain, 2019; doi: 10.1093 / brain / awz099)

Source: University of Kentucky / NIH / National Institute on Aging

- Daniel Albat