Over five thousand residents of the Antioquia department in Colombia are carriers of the genetic mutation, which is responsible for the onset of the first symptoms of Alzheimer's disease after the age of 40. By researching the brains of people at risk, scientists hope to understand what causes this type of dementia and how it can be prevented.
The Antioquia Department is a region of Colombia, known for its mountainous areas, coffee cultivation and ... drug cartels, which at the headquarters of the department in the late 1980s turned out to be the capital of the department - Medellin. Genetic mutation, which carriers are residents of Antioquia, arouses great interest among researchers dealing with neurodegenerative diseases. It is believed that for the first time in Colombia this mutation was brought by the Spanish conquistadors 375 years ago. Today, its carriers are over 5,000 people, belonging to about 25 families.
This mutation causes the appearance of symptoms of Alzheimer's disease in very young people, even 40 or 50 years old, lowering the quality of life and shortening it. Researchers hope that understanding the mechanisms behind the development of Alzheimer's disease in people who carry the mutation from Colombia will help not only successive generations threatened by the emergence of hereditary disease, but also millions of people around the world.
β-amyloid and tau protein
For many years, scholars thought that Alzheimer's disease is mainly associated with a protein called β-amyloid, which is formed in large quantities in the brains of the ill. In earlier studies, it was proved that in the Antioquia department with a genetic mutation, this protein was able to accumulate in the brain structures many decades before the appearance of symptoms of the disease. Even a few preparations were made that were able to lower the level of β-amyloid in the brain of a sick person, but it turned out that the reduction of the amount of this protein itself does not mean a reduction in the burden of disease symptoms.
The other protein that is suspected to be associated with the development of Alzheimer's disease is tau protein. Under normal conditions, this protein stabilizes structures that allow neurons to communicate with each other. However, the brains of people with Alzheimer's disease produce large amounts of improperly formed tau protein, which instead of stabilizing the previously mentioned structures causes them to tangle and merge into conglomerates. It was noted that the amount of these aggregates is associated with the number of symptoms and the burden of Alzheimer's disease.
Look at the brain
A few years ago, scientists developed radioactive biomarkers that allow the observation of tau protein in real time using positron emission tomography.positron emission tomography, PET). The technique, using PET and this biomarker, is being tested on the participants of the pilot study with the participation of 24 people from the family whose members are carriers of the Colombian genetic mutation.
With this technique, it was demonstrated for the first time that the tau protein begins to accumulate in the brains of people with a genetic mutation six years before the first symptoms of Alzheimer's disease appear. It has also been shown that the accumulation of tau protein in brain-related structures, e.g. speech, actually causes problems with speaking in a sick person.
Researchers not only observe changes in the brains of people at risk of having an inherited form of Alzheimer's disease, but also test a new drug on them that is supposed to prevent the onset of disease symptoms. The study is expected to last until 2022 and it is likely then that we will find out whether the tau protein is actually responsible for the development of Alzheimer's disease, or maybe similar to β-amyloid can not be the target of treatment.
S. Reardon,Pioneering Alzheimer's study in Colombia zeroes in on enigmatic protein. Nature 555 (2018) 567-568