Brain cells that normally help protect the brain may play an unexpected role in cognitive decline as we grow older. Scientists have discovered that cells responsible for maintaining the protective coating around nerve fibers can become dysfunctional with age, potentially contributing to the gradual loss of memory and thinking abilities. The research, published in Nature Medicine, challenges the long-held belief that these cells are always beneficial.
By examining human brain tissue and conducting experiments in mice, researchers found evidence that problems with these normally supportive cells can damage nerve fibers and interfere with cognitive function. The discovery also points to a possible new approach for protecting the aging brain. Drugs that act on the biological pathway involved are already being used to treat other neurological conditions, raising hopes that existing treatments could eventually be adapted to combat age-related cognitive decline.
Scientists Discover Changes in the Aging Brain The study was led by researchers from the University of Edinburgh and the UK Dementia Research Institute, who investigated how changes in the brain relate to declining cognitive abilities later in life. Their research focused on the Lothian Birth Cohort 1936, a group of people whose cognitive abilities have been tracked from childhood into old age. This unusually extensive record allowed scientists to investigate how thinking and memory changed over decades.
Between ages 70 and 82, participants underwent assessments measuring memory, the speed at which they processed information, and their ability to understand spatial relationships. Of the 1,091 people enrolled in the cohort, 866 completed additional cognitive testing after age 70. Nearly everyone experienced at least some decline, but the rate varied considerably.
These differences gave researchers an opportunity to investigate what might distinguish brains experiencing faster deterioration from those aging more gradually. When scientists examined brain tissue collected after death from a subset of participants, they discovered a striking pattern. Individuals who had experienced greater cognitive decline tended to have fewer large nerve fibers, along with an abnormal buildup of unhealthy myelin.
Myelin is the protective coating that surrounds nerve fibers, helping electrical signals travel efficiently through the brain. Although this insulation is essential for normal brain function, the findings suggest that excessive or abnormal myelin may become part of the problem. The changes were especially pronounced around the large nerve fibers that remained.
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