Meet the pericyte, a new player in Alzheimer’s

November 18, 2010

Cells in the brain called pericytes play a crucial role in the development of neurodegenerative diseases such as Alzheimer’s, according to research in the November issue of the journal, Neuron.

“For 150 years these cells have been known to exist in the brain, but we haven’t known exactly what they are doing in adults,” Dr. Berislav Zlokovic said in a news release from the University of Rochester Medical Center. “It turns out the pericytes are very important for helping maintain a brain environment crucial to the health of neurons. The pericyte offers us an exciting new target for new treatments for neurodegenerative diseases.”

Pericytes wrap around capillaries like ivy around a pipe, to help maintain the structural integrity of the tiny blood vessels. They play a central role in determining the amount of blood flowing in the brain and in maintaining the barrier that stops toxic substances from leaking out of the capillaries and into brain tissue. When researchers reduced the number of pericytes in the brains of laboratory mice, they observed a reduced blood flow, greater exposure to toxic substances, impaired learning and memory, and damage to neurons, or nerve cells. The mice experienced an array of problems that closely match the brain abnormalities experienced by people with neurodegenerative conditions, such as Alzheimer’s.

Read the news release.

Read the abstract in the journal, Neuron (including instructional video).


Understanding dementia, from the Cleveland Clinic

May 25, 2010
Understanding dementia

Deciphering the role of plaques and tangles — on the Huffington Post

May 19, 2010

Dr. Scott Mendelson, author of the book, “Beyond Alzheimer’s: How to Avoid the Modern Epidemic of Dementia,” is a psychiatrist in Roseburg, Ore. who writes for the Huffington Post.

I asked him about the debate among scientists about whether the “plaques” and “tangles” that are hallmarks of Alzheimer’s are actually caused by the disease or byproducts of the neurodegeneration that takes place. And here is his reply:
“You ask a very interesting question. What appears to be the case is that the ‘plaques and tangles’ are both the cause and byproducts of the disease.

There is a big circle of damaging processes in the illness. Thus, for example, accumulation of amyloid plaque can cause inflammation and poor blood supply that can cause oxidative damage and other lesions. In turn, inflammation and oxidative stress can increase deposition of amyloid. Thus, the illness can begin with inflammation and oxidative damage, or with a genetic predisposition to amyloid deposition. There are many such ‘circles’ of damage in the illness than can be generated by different problems. I hope this oversimplified answer is helpful.”

Read Dr. Scott Mendelson’s “The Unfortunate NIH Report on Alzheimer’s Disease”

What is the hippocampus? And why should we care?

March 30, 2010
My Dad was dating the woman he would marry when the Lancet published research in 1985 about how “the decline of all higher cognitive functions in senile dementia of the Alzheimer type is attributable to histopathological changes in the hippocampal formation.”

Twenty-three years later, the year his wife got him settled into Silverado Senior Living, research still focused on the hippocampus, deep in the brain. It seems a larger hippocampus may protect people from the effects of Alzheimer’s disease-related brain changes, “an exciting area of research,” according to Professor Clive Ballard, director of research for the Alzheimer’s Society in London.

It’s not that any of this knowledge or experimentation could help my Dad now, or even back in 1985, that I find myself wondering about this structure, this region, this whatever-it-is piece of the brain. It’s the purple area in this drawing provided by Dr. Jim Phelps, an Oregon psychiatrist. This is a slice image, looking deep in the temporal lobe, which is above and infront of the ear on either side of the head.

He explains that the hippocampus–part of the innermost fold of the temporal lobe–is instrumental in helping us store memories. And, he gives three reasons why we should care about it:

1. This part of the brain appears to be absolutely necessary for making new memories. Alzheimer’s disease affects the hippocampus first and severely, which is why memory (or the ability to make new ones) is usually the first thing to start to falter in Alzheimer’s.

2. The hippocampus appears to shrink in severe mental illnesses, including severe depression and schizophrenia.

3. Estrogen has a direct effect on the hippocampus. Research on the role of estrogen in preventing Alzheimer’s is underway.

So this is what we know now. We can only imagine what we’ll know another 23 years from now.

ScienceDaily report from 2006 on the size of the hippocampus as it relates to Alzheimer’s disease

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