Brain Aging (and Injury?)

Researchers at the Stevens Institute of Technology (New Jersey) have reported findings that affect memory and motor control. While I usually don’t focus on early exploratory research, what they’ve done has implications affecting a large number of people.

Most studies of brain function focus on electrical connections in the brain. The Stevens group approached the topic from a mechanical engineering perspective, looking at the physical structure.

So called “white matter” nests around neurons in the brain and carries electrical messages from one neuron to another. As people age — and potentially under other circumstances — this white matter develops lesions that interrupt message transfer. The interruptions affect the ability to recall things, as well as movement control. In medical terms, these lesions are “deep and periventricular white matter hyperintensities.”

The Stevens group identified that leaks of cerebral spinal fluid into the brain can cause these lesions. The lining separating the spine and the brain is flexible and has to stretch and contract with changes in spinal fluid pressure. Over time, it simply wears out, fluid leaks into the brain, and lesions multiply.

The team mapped the strain placed on ventricular walls, the linings of fluid-filled chambers deep in the brain, as waves of pressure pulse through the subject’s cerebral spinal fluid, or CSF. They found that hyperintensities tend to occur near areas that must stretch more to accommodate pressure changes of the circulating CSF because, as such areas wear thin, CSF can leak into the brain and cause lesions.

Science Daily, 17 December 2021 (2)

At least in theory, these leaks can also occur from Traumatic Brain Injuries, particularly those affecting the back of the head and neck, near the boundary separating the spinal column and brain.

The geometry of the area allows scientists to predict where leaks will occur. Now, is it possible to fix or prevent them?

The factors affecting CSF pressure may include age, posture, blood pressure, and medications. Lower than average levels of CSF pressure appear to be associated with glaucoma, while abnormally high levels or rapid variation may be associated with lesions.

Aristotle is right, again, of course. There is a lot to be said for sitting up straight and a middle path on diet and exercise that leads to consistent CSF pressure. Boring as it may be, trips to the hospital represent the kind of excitement best avoided.

Sources:

  1. Valery L. Visser, Henry Rusinek, Johannes Weickenmeier. Peak ependymal cell stretch overlaps with the onset locations of periventricular white matter lesions. Scientific Reports, 2021; 11 (1) DOI: 10.1038/s41598-021-00610-1
  2. Stevens Institute of Technology. “Wear and tear in vulnerable brain areas lead to lesions linked to cognitive decline.” ScienceDaily. ScienceDaily, 17 December 2021. www.sciencedaily.com/releases/2021/12/211217172730.htm
  3. https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/cerebrospinal-fluid-pressure
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7150067/
  5. https://www.ahajournals.org › doi › pdf › 10.1161 › 01.res.1.5.389
  6. https://pubmed.ncbi.nlm.nih.gov/23733117/

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