A new type of dementia has been identified. While it may look like Alzheimer’s disease, it differs in significant ways. Researchers suspect it’s even more prevalent than Alzheimer’s disease – and may be part of a mixed-dementia diagnosis – but that remains to be seen.

The new type of dementia is called limbic-predominant age-related TDP-43 encelopathy or LATE dementia. The symptoms of LATE dementia and Alzheimer’s disease can appear to be similar, but while Alzheimer’s disease is the accumulation of plaques (beta-amyloid proteins) and tangles (tau proteins) in the brain, LATE dementia occurs because of the misfolding of accumulated TDP-43 proteins in the brain. 

If people with LATE dementia have been treated with standard medications that target Alzheimer’s disease, they have generally not responded to the treatment at all, because there are two different mechanisms at work in these two neurological diseases.

Here’s what we know about LATE dementia so far. It occurs in the very elderly (over 20% of people who are 85 or older show signs of LATE dementia). LATE dementia affects numerous cognitive areas in the brain, including memory.

While it seems that LATE dementia progresses much more slowly than Alzheimer’s disease, it can eventually have the same net effect of continuous impairment in functioning. And some of the very elderly may have both LATE dementia and Alzheimer’s Disease (or another type of dementia).

TDP-43 proteins are found in three parts of the brain in LATE dementia. They are the amygdala (the part of the brain responsible for “fight or flight” and related emotions), the hippocampus (the part of the brain that is responsible for long-term memory and spatial navigation), and the middle frontal gyrus (the part of the brain that is believed to handle spoken and written language).

As with many dementias, LATE dementia can be confirmed definitively after death. However, researchers are hoping the the biomarkers of LATE dementia can be identified so that clinicians are able to distinguish between it and Alzheimer’s disease while people are still living.