The British described the aging of the brain in the largest sample
Denis Strigun, Naked Science
An international group of scientists has conducted the largest study of age-related changes in the white matter of the brain. The results of the work are published in the journal Nature Communications (Cox et al., Aging and brain white matter structure in 3,513 UK Biobank participants).
Here and below are drawings from an article in Nature Communications
Understanding how the brain ages requires describing the changes that occur with white matter. Past studies have shown that age-related cognitive decline may be associated with demyelination of its axons, which reduces the quality of interneuronal interaction. However, despite a large number of studies, data on changes in white matter are contradictory and are associated with the hemispheres or gender of a person.
In their study, scientists from the University of Edinburgh and the University of Texas at Austin conducted the first large-scale analysis of such changes. To do this, the authors used images of 3,513 people aged 44-72 years, taken using diffusion spectral tomography (dMRI). This method allows reconstructing three-dimensional tissue models based on the diffusion of water molecules. The data was obtained from the UK Biobank.
Tractography (reconstruction of neural pathways) in the new work was carried out using additional criteria – orientation and density of axon bundles in white matter (NODDI). So, in addition to the traditional fractional anisotropy FA (describes the structure of the brain by "orientation") and the average diffusion coefficient MD (the level of diffusion of molecules), the authors studied intracellular (ICVF), extracellular (ISOVF) diffusion, as well as pathway complexity (OD).
Age dynamics of indicators in different areas of white matter.
The results showed that with age, the asynchrony of FA, ICVF increases in the white matter, MD and ISOVF increase, and OD decreases. This indicates tissue degeneration. Pronounced differences were in the lower frontal-occipital bundle, the lower longitudinal bundle, the upper longitudinal bundle (responsible for semantic processing of speech), some thalamic radiances (end parts of afferent tracts) and frontal forceps (connect the cortex of the frontal lobes).
At the same time, age differences were not observed in the cingulate gyrus (responsible for the avoidance reaction and autonomous regulation of the cardiovascular system), the corticospinal tract (mediates motor signals to the spinal cord), auditory radiance (refers to the auditory pathways) and other parts of the brain. Thus, age did not correlate with structural changes in the white matter, which should lead to impaired motor function and hearing.
According to the authors, the data obtained are preliminary and in the future will help to find out why the brain and cognitive functions of some people cope better with aging. It is noted that tractography based on such a number of images is unique – until now, scientists have been limited in such materials. The next step will be to search for genetic and environmental factors associated with age-related changes in white matter.
Portal "Eternal youth" http://vechnayamolodost.ru
19.12.2016