Alzheimer’s – the most common form of dementia – leads to the death of nerve cells in the brain. A new therapy should be able to counteract this development.
Published: 04/14/2023, 19:58
Alzheimer’s – also known as Alzheimer’s dementia or Morbus Alzheimer – is the most common form of Alzheimer’s with around two thirds of the cases dementia. It is an incurable disorder of the brain in which nerve cells die over time. As a result, people who develop Alzheimer’s become increasingly forgetful, confused and disoriented.
Alzheimer’s: Whoever falls ill shows the typical symptoms of forgetfulness and insecurity.
Bild: keystone
US researchers have now succeeded in stimulating the formation of new nerve cells in the brain of adult mice with Alzheimer’s disease, thereby improving memory. That’s what a study by the University of North Carolina said USA which was published in the scientific journal «Cell Stem Cell».
New generation of nerve cells disturbed by Alzheimer’s
That certain neurons can renew themselves throughout life is a relatively recent discovery and is called adult neurogenesis. For a long time, scientists assumed that no new nerve cells could form after the end of childhood.
However, adult neurogenesis takes place primarily in a small part of the brain – the hippocampus, where memory is also formed. In Alzheimer’s disease, this formation of new nerve cells is disrupted at an early stage, which explains the increasing memory loss in patients.
Improved memory in two steps
The research team led by Juan Song has now succeeded in improving the memory performance of mice through two genetic adaptations of a specific brain area (supramamillary nucleus).
In the first step, the formation of new brain cells in the hippocampus of the mice was stimulated by gene therapy. The new gene caused the nerve cells to form a specific visual pigment on their surface. The nerve cells could then be stimulated by a tiny light probe that was inserted into the brain. As a result, the number of nerve cells increased.
In the second step, the new nerve cells were activated. This happened via a second gene therapy, through which a specific enzyme multiplies in the nerve cells. This enzyme is essential for memory.
Trials in two mouse models successful
The result: the mice recognized objects in their cage and were less anxious in experiments. This was possible with two different mouse models – i.e. with two groups of mice in which the animals developed Alzheimer’s disease due to different genetic changes.
The treatment had another advantage: as a result of the therapy, certain defense cells in the brain, the so-called microglia, began to break down harmful protein deposits in the brain (beta-amyloids). They are considered to be the main triggers for Alzheimer’s disease and other forms of dementia.
Results can only be transferred to humans to a limited extent
The therapy cannot simply be transferred to humans, since the genetic material has to be modified for the first step of the therapy. However, studies have shown that neurogenesis still occurs, at least to some extent, in people entering adulthood. The authors of the study therefore hope that a similar effect in humans will result from a deep brain stimulation, a so-called brain pacemaker. Brain pacemakers are used in Morbus Parkinson been used clinically for years with success.
According to the authors of the study, the second step of the therapy could in principle also be carried out in people with Alzheimer’s disease. However, the new therapeutic approach is not yet ready for clinical use in humans. The next step would be experiments on larger animals. (t-online)
Sources:
- cell.com: “Activation of hypothalamic-enhanced adult-born neurons restores cognitive and affective function in Alzheimer’s disease”. (Stand: April 2023; englisch)
- gesundheit.gv.at: “Alzheimer’s dementia”. (Status: January 2021)