In a new study, researchers have presented a model that explains why memory deteriorates as the body ages.
They suggest that with age, the brain receives an increased load from the heart’s beating as the body’s large arteries stiffen over the years, causing damage to the smallest blood vessels in the brain.
The research was conducted by a team from Umea University.
Human memory deteriorates with increasing age, which most people experience sooner or later, even among those who do not develop diseases such as Alzheimer’s.
Similarly, a connection between the aging of the brain and the body is well known. However, the exact nature of this association is not known.
In the study, the team created an explanatory model that starts with the heartbeat and carries through the largest arteries in the body all the way to the finest vessels in the brain.
An important feature of the model is that it provides a rationale of why some cognitive processes may be particularly at risk for the proposed mechanism.
The researchers suggest a chain of events on how the aging of the brain and vessels are related.
As the human body ages, large arteries, such as the aorta, stiffen and lose a large portion of their ability to absorb the pressure increase generated as the heart ejects blood into the arteries.
Such pressure pulsatility is instead transmitted to smaller blood vessels, for example, those in the brain.
The smallest blood vessels in the brain, the capillaries, are subjected to the increased stress that causes damage to cells within and surrounding the capillary walls.
These cells are important in the regulation of the capillary blood flow. If the smallest blood vessels are damaged, this is detrimental to the ability to increase the blood supply to the brain when coping with demanding cognitive processes.
According to the researchers, the hippocampus in the brain is particularly vulnerable.
The structure in that part of the brain is important for the episodic memory, that is, the ability to remember events from the past.
The vulnerability of the hippocampus relates to the fact that it is located close to the large vessels and thus is exposed to the increased load early in the chain.
In a young and healthy person, the pulsations are soft, but in an aging person, the pulsations can be so powerful that they affect the brain tissue and can damage the blood supply to memory processes.
The Umeå researchers’ model is based on a number of previous studies from the last five years.
The lead author of the study is Lars Nyberg, professor at Umeå University.
The study is published in Trends in Cognitive Sciences.
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