Our Brain Keeps Making New Cells as We Age…Except in Alzheimer’s Disease
Is there a link between the stem cells in your brain and Alzheimer’s disease? Most people likely don’t know that there are stem cells in the brain, so the lack of cells there may come as a shock. So let’s explore.
Understanding Alzheimer’s Disease and the Hippocampus
It’s well known that the hippocampus is a key area of the brain associated with Alzheimer’s disease. The hippocampus lives deep in the brain in the medial temporal lobe and rests just above the brain stem. While there is still much to learn about the hippocampus, it is generally believed that it plays a key role in both long- and short-term memory and that it also serves as one of our primary GPS systems, allowing us to navigate our environment. Being a structure of the limbic system, it is also a center for our emotions and mood.
We do know that in Alzheimer’s disease, the hippocampus experiences a significant loss of cells, making it, as already mentioned, one of the primary brain structures affected by the disease. Now, a new study investigates the other end of the nerve cell spectrum: not loss of cells but the generation of new nerve cells in Alzheimer’s. Let’s review.
Your Body is a Stem Cell Production Machine
Most people don’t know that they have stem cells in their bodies naturally replacing dying cells every day. These cells live in almost all tissues, from the heart, to your muscles, to your bones, to your brain. If you didn’t have lots of functioning stem cells in your body, you wouldn’t last long. Hence, more diseases are being viewed as stem cell problems causing an inability to replace or heal damaged tissue.
Neurogenesis in adults is a relatively new concept. We were taught in medical school that the brain didn’t have the ability to repair damaged cells. Now we know that this does happen in a few parts of the brain. One of those is the hippocampus, which is involved in memory and learning.
Neurogenesis Active in Aging Patients…Except in Alzheimer’s Disease
In a new study, nerve cell production (neurogenesis) by the hippocampus in elderly Alzheimer’s brains was compared to nerve cell production by the hippocampus in elderly healthy brains. Researchers confirmed first that the human hippocampus continued to make new nerve cells all the way into the late years of life in healthy subjects even in their 80s. In those with Alzheimer’s disease, however, neurogenesis declined as the disease progressed. So while we know existing brain cells degenerate and die in Alzheimer’s disease, it seems the hippocampus in the brain is also making fewer and fewer new cells in the process.
More on Alzheimer’s Disease and Other Forms of Dementia
The most common form of dementia is Alzheimer’s disease (aka senile dementia). As more and more brain cells are destroyed in the disease, memory, behavior and emotions, and other cognitive processes progressively decline. While genetics is believed to be the primary risk factor for Alzheimer’s, there are many other associations that have been made with the disease. Let’s review some findings on Alzheimer’s disease:
- One lab-based study found that Alzheimer’s disease could be eradicated in vitro in stem cells in which the ApoE4 protein (the gene associated with Alzheimer’s) had been converted to ApoE3.
- Those who carry a genetic risk for Alzheimer’s, one study suggests, are much more susceptible to cognitive decline following surgery using a general anesthesia.
- Could there even be a link between Alzheimer’s and nonsteroidal anti-inflammatory drugs (NSAIDs)? Absolutely—a strong association was made in one study a few years ago.
- Another study directly linked Alzheimer’s to busy highways when it found that the closer people live to these high-traffic areas, the higher their risk for Alzheimer’s.
The upshot? Viewing Alzheimer’s as a disease where the stem cells that have to constantly replace dying brain cells that aren’t working is novel. This may mean that one way to help the disease is finding ways to add new stem cells to the brain or fix those that are already there. Hopefully, all of this leads to better treatments for this disabling problem.