We all know that our memory becomes less reliable as we get older. It is not uncommon for older people to start forgetting dates, tasks on their agenda, or even where they put their keys, etc. But where is the line between simply being forgetful and signs of something more serious like a disease?
A new study from the University of Washington School of Medicine examined over 100 research articles that looked at the blood-brain barrier. It is thought that this barrier between blood vessels and other cells and components of brain tissue is crucial when it comes to having a well-functioning brain. Researchers tried to understand how it changes as we get older.
It is important to acknowledge that the question about how changes in the barrier affect different functions of the brain still remains unclear.
William Banks, the author, and director of the research highlights that there is much unknown when it comes to understanding how the blood-brain barrier changes with age. Scientists can’t be sure whether these changes are a part of a normal aging process or can be interpreted as an early sign of disease.
What is a blood-brain barrier?
There are a few important functions of the blood-brain barrier that allow the brain to remain healthy and work properly. This delicate part of the brain has the primary function of preventing the substances from the blood to leak into the brain. This is very important for normal brain function since the brain can sustain exposure to only some substances contained in the blood. Another important function of the barrier is to regulate the transfer of nutritional substances from the blood into the brain. It also has an important role when it comes to toxin removal out of the brain. Scientists seem to believe that we can associate diseases linked to aging, like Alzheimer’s, multiple sclerosis (MS), and diabetes with impaired functions of the blood-brain barrier.
To understand what the role of the unhealthy barrier is when it comes to disease development, we first need to look at how the normal aging process works in a healthy barrier.
Research findings – healthy vs diseased
Scientists found that a small leak in the barrier between blood and brain is normal and common even for healthy people. It is linked to normal forgetfulness that comes with a natural process of aging. Now the question is if this leak can be found in the beginning stages of Alzheimer’s disease?
Research shows that more changes in the blood-brain barrier are found in individuals who carry the gene allele considered to be the biggest risk for developing Alzheimer’s disease. This allele is the cause of accumulating plaque in the brain that happens if the brain can’t discharge certain peptides out of the system. The pump in charge of that process is located in the blood-brain barrier and becomes less efficient as all individuals get older, but even more so for people with Alzheimer’s.
The role of pericytes and astrocytes
Another important conclusion from the research implies that changes in two types of cells occur with the aging process in the blood-brain barrier. Those two types of cells are pericytes and astrocytes.
How is this related to Alzheimer’s? Research suggests that when a leak in the barrier occurs with Alzheimer’s patients, the first type of cell, the pericytes, decreases in volume – we lose them. On the other hand, the second type, the astrocytes, becomes overly active. Thus, it is believed that keeping the healthy function of pericytes could be a solution toward normal work of the blood-brain barrier. Treating patients with the factors these cells produce or transplanting them might be the key to the healthy barrier between blood and brain.
Some researchers highlight that there are some lifestyle habits, like regular exercise, keeping track of calorie intake, or the drug rapamycin that can be helpful with keeping the pericytes healthy.