A recent paper [ Proc. Natl. Acad. Sci. vol. 109 pp. 3199 – 3200, 3510 – 3515 ’12 ] found a way to dissolve the senile plaques in a mouse model of Alzheimer’s disease. Essentially it uses le Chatelier’s principle to do so, although it is doubtful that Ayurvedic praticioners were thinking along these lines when they first gave an extract of Ashwagandha (Indian ginseng) to improve memory. As the examples of digitalis and curare show, you ignore folk pharmacology at your peril. Whole Foods and health food stores certainly don’t and make piles of money as a result, whether or not their nostrums do any good. The FDA stands by gnashing its teeth as by law it cant’ touch this sort of thing.
First, a bit of background for the nonMDs. Just as the gray hair on the head of an 80 year old looks the same under the microscope as one from a prematurely gray 30 year old, the brain changes of Alzheimer’s disease are the same regardless of the age of onset. Alois Alzheimer described the microscopic changes in a youngish person and the disorder firstt came to be known as presenile dementia.
There are basically two distinctive changes (1) senile plaques outside neurons (2) neurofibrillary tangles inside neurons. Like all dementias there is a severe loss of neurons in addition. The major protein component of the senile plaque is a 40+ amino acid peptide called the Abeta peptide. It is a fragment of a much larger protein (the amyloid precursor protein). The major protein component of the neurofibrillary tangle is hyperphosphorylated tau.
Thinking about pathologic changes and neurologic disease has been simplistic in the extreme. Both plaques and tangles were assumed to be causative. However there are 3 possible explanations any microscopic change seen in disease. The first is that they are causative (which is what everyone had assumed for years). The second is that they are a pile of spent bullets, that the cell used to defend itself against the real killer. The third is they are tombstones, the final emanations of a dying cell.
Large battles have occurred about the causative roles of tau and Abeta in the disease. As usual, the best evidence genetics, as there are mutations these proteins associated with dementia. The evidence for Alzheimer causation is strongest for Abeta and its parent the amyloid precursor protein.
Now to the paper itself. Mice were created with mutations known to cause Alzheimer’s disease in man. They developed senile plaques and were then given Ashwagandha extract. The plaques got smaller. This is surprising in itself, as huge attempts have been made to solublilize the aggregated Abeta in plaques and determine its structure without notable success Lots more work needs to be done, but they think the liver begins chewing up Abeta, forcing the insoluble Abeta in the plaque to solublilze and move to the liver. Le Chatelier’s principle in action !
The mice got smarter on various tests, but I take all this stuff with a grain of salt. Animals are smart at doing what they need to do to survive, and running mazes is not one of them. For that matter, how good would with Newton or Einstein have been running a maze.
The crucial point is the plaques got smaller. This sort of thing is exactly what the field needs — a slightly different approach. Immune attacks on the plaques have been a disaster, and inhibiting the enzyme complex which fragments the amyloid precursor protein into Abeta is likely to have other effects, as the complex is responsible for processing many different proteins.
At this point, they aren’t using pure compounds, but extracts of the plant which sure to a mixture. Stay tuned. First the work needs to be replicated. Nice to see that most of the work is from India.