Pimples in the brain

Bacteria – causative agents of acne found in the brains of patients with Alzheimer's syndrome

Anna Kaznadzei, N+1

Neuroscientists from the University of Bristol have found out that the bacterial compositions of the brain in a healthy person and a person with Alzheimer's syndrome differ from each other. Scientists suggest that bacteria can cause inflammation, which is considered one of the causes of the disease. One of the types prevailing in the samples of sick people compared to healthy ones was Propionibacterium acnes, which, among other things, causes acne on the face. The study is published in Frontiers in Aging Neuroscience (Emery et al., 16S rRNA Next Generation Sequencing Analysis Shows Bacteria in Alzheimer's Post-Mortem Brain). 

Alzheimer's disease is the most common neurodegenerative disease, which usually affects people over 65 years of age. At the moment, this syndrome has been diagnosed in at least thirty million people. First, there is a violation of short-term memory, after which the disease develops, affects long-term memory, cognitive functions of the brain, speech and the ability to navigate in the environment are disrupted. The functions of the body are disrupted one after another, and then a fatal outcome follows. The average life time after an early diagnosis is about seven years.

Currently, the causes and mechanisms of the course of Alzheimer's disease are not completely clear. The key features of the syndrome are the accumulation of amyloid plaques and neurofibrillary tangles in brain tissues. According to a number of theories, this may be due to inflammatory processes of the brain, and scientists suggest that they, in turn, may be associated with its bacterial component.

Previously, it was believed that most of the human body is sterile, but studies in recent decades show that bacteria inhabit almost all of its areas, both external and internal. The brain is no exception. Using new generation sequencing (NGS), the scientists analyzed a small sample of brain tissues from 14 patients aged 62 to 89 who had Alzheimer's disease and compared them with 12 control samples.

Perhaps the protein accumulating in the brain tissues of patients with Alzheimer's syndrome initially served as a protection against bacteria. In the course of this study, it turned out that the bacterial composition (determined by the ribosomal 16S gene) differs in patients and healthy people. Firstly, despite the fact that it is impossible to give accurate numerical estimates using such a technique, even rough estimates, according to scientists, demonstrate 5-10 times more bacteria in brain tissues in patients with Alzheimer's syndrome. Secondly, the ratio of different groups of bacteria in the samples differs; in particular, patients with Alzheimer's have a higher proportion of Actinobacteria (Actinobacteria) compared with proteobacteria.

On the left: percentage distribution of bacteria of different groups in samples (AD) and control samples (C), Frozen and fixed with formalin (FFPE). On the right: the number of readings obtained from the bacterial 16S RNA sequencer in healthy and sick samples

In the brain samples of sick people, the predominance of bacteria living on the skin and in the mucous membranes was noted, including Propionibacterium acnes, which is a conditional human pathogen. In normal mode, it lives peacefully in the body, but in case of changes in conditions, it can cause diseases – in particular, cause acne, or acne, as well as much more serious complications, for example, postoperative. It releases substances into the environment that cause tissue inflammation, and scientists believe that this type may be one of the important causes of the development of Alzheimer's syndrome.

Portal "Eternal youth" http://vechnayamolodost.ru  19.07.2017