Scientists discovered why some people's brains age faster

In people with faster cognitive decline, the brain contains more oligodendrocytes — cells that form the myelin sheath of nerve fibers. At the same time, the protective layer around the nerves becomes abnormally thickened, while the fibers themselves become thinner. This was demonstrated by a study published in the journal Nature Medicine.

Oligodendrocytes produce myelin — a sheath that helps nerve signals travel quickly through the brain. Scientists suggested that an excess of these cells is not always beneficial and may be associated with age-related changes in thinking and memory.

Researchers analyzed data from participants in a long-term study of residents of the Scottish Lothian region. Their cognitive abilities were assessed from childhood and retested after the age of 70. Scientists then examined brain samples from some participants, donated after death. In the tissues of people whose cognitive functions declined more rapidly, more oligodendrocytes were found, along with signs of myelin sheath damage.

Additional experiments in mice helped identify a possible mechanism. In animals in which the NRF2 gene — involved in protecting cells from damage — was knocked out in oligodendrocytes, memory formation was impaired in the water maze test. They also exhibited changes in nerve fibers and myelin similar to those found in humans.

The authors suggest that disruptions in NRF2 function in oligodendrocytes may contribute to accelerated brain aging. This mechanism requires further study: the human part of the research identified an association but did not prove a causal relationship, and the tissue analysis covered a small number of people.

Since NRF2 activity can be modified using certain drugs, the results may help in the search for approaches to preserving cognitive function. However, medications have not yet been tested in this study as a means of combating brain aging.