Dementia is a disease that affects many people, and new forms of it are still being discovered today. For example, the neurodegenerative pathology called LATE . Alzheimer’s disease is now one of the most prevalent diseases in the world with over 46 million people affected.
Thus, the study of dementias in general is one of the greatest challenges facing medicine today. Despite the progress made, there is still a lot to discover. For that, we must continue to do research and studies. One example is the emergence of a new type of dementia, LATE dementia.
Although there are several known types of dementia and although it is possible that they coexist, some inconsistencies have attracted the attention of scientists. For example, in patients with severe Alzheimer’s disease and in those over the age of 80, cognitive decline exceeded expectations. It seems that this new type of dementia could explain these dysfunctions.
The acronym LATE refers to the predominantly limbic age-related TDP-43 encephalopathy. LATE is in fact similar to the TDP-43 protein. We have already discovered the relationship of this protein with other degenerative diseases, such as Amyotrophic Lateral Sclerosis (ALS) or Fronto-Temporal Lobar Degeneration (DLFT).
The proposed new dementia, LATE, occurs in old age, especially in people over 80 years old. Thus, working groups for the diagnosis of Alzheimer’s disease have proposed this term ( Late meaning Tard in English).
Indeed, this term makes it possible to include other general proteinopathies of TDP-43 which are associated with cognitive impairment. For example, hippocampal sclerosis and its subtypes are incorporated into this terminology.
TDP-43 proteinopathy has been associated with progressive amnesic syndrome similar to that of Alzheimer’s disease. However, the lack of knowledge and tests to diagnose proteinopathy complicates the diagnosis. This situation has led some scientists to argue that a high percentage of people who have been diagnosed with Alzheimer’s disease may in fact be suffering from LATE.
How to observe it
Currently, alterations in TDP-43 are observed only by performing a postmortem brain autopsy. On the basis of this type of study and its results, the experts proposed a course of the disease in 3 phases:
- Proteinopathy in tonsils: It has been observed that the volume and shape of tonsils are affected in LATE. These structural changes are an indication of the onset of cognitive decline. In fact, the relationship between these observations in the amygdala and the change due to LATE is much stronger than that between hypocampic atrophy and Alzheimer’s disease.
- Hippocampal proteinopathy: Hippocampal atrophy has been found to be more severe in patients who have had LATE than in those who have had pure Alzheimer’s disease. This atrophy of the hippocampus is asymmetric. Also, she seems to follow a back and forth path
- Proteinopathy in the mid-frontal gyrus. This area is located in the frontal lobe. Dementia would therefore already affect the higher cognitive processes of attention or learning
Like other dementias, LATE dementia is also accompanied by an amnesic syndrome. It can also evolve to affect other cognitive areas that affect activities of daily living. However, some aspects show a somewhat different pattern.
The elements that we have to date however still remain very limited. However, they indicate that patients with pure LATE show a more gradual decline than those with Alzheimer’s disease. And, as expected, people with LATE and Alzheimer’s comorbidities experience a more severe and faster decline.
People with LATE have a more marked deterioration in episodic memory. However, they also present a serious impairment of other functions, especially in the advanced stages. For example, it seems that patients who have good verbal fluency despite a poor ability to remember a list of words are at greater risk of developing LATE.
Future directions for LATE dementia
Finally, it is still early to establish neuropsychological profiles. Furthermore, we don’t even have neuroimaging instruments to observe protein alteration over the course of life.
Therefore, we are left to wait for future research to provide new biomarkers and indicators , as well as motor, autonomic or neuropsychiatric characteristics.