Alzheimer’s Disease and Insulin
A 2011 study isolated a substance (CEppt) in the cinnamon plant that inhibits development of Alzheimer's disease in mice. CEppt, an extract of cinnamon bark, seems to treat a mouse model of Alzheimer's disease.
Insulin and its related proteins have been shown to be produced inside the brain, and reduced levels of these proteins are linked to Alzheimer's disease.
Considerable interest in IDE (insulin-degrading enzyme) has been stimulated due to the discovery that IDE can degrade amyloid beta (Aβ), a peptide implicated in the pathogenesis of Alzheimer's disease. The underlying cause or causes of the disease are unclear, though the primary neuropathology observed is the formation of amyloid plaques and neurofibrillary tangles. One hypothesized mechanism of disease, called the amyloid hypothesis, suggests that the causative agent is the hydrophobic peptide Aβ, which forms quaternary structures that, by an unclear mechanism, cause neuronal death. Aβ is a byproduct generated as the result of proteolytic processing of the amyloid precursor protein (APP) by proteases referred to as the β and γ secretases. The physiological role of this processing is unclear, though it may play a role in nervous system development.
Numerous in vitro and in vivo studies have shown correlations between IDE, Aβ degradation, and Alzheimer’s disease. Mice engineered to lack both alleles of the IDE gene exhibit a 50% decrease in Aβ degradation, resulting in cerebral accumulation of Aβ. Studies of genetically inherited forms of Alzheimer’s show reduction in both IDE expression and catalytic activity among affected individuals. Despite the evident role of IDE in disease, relatively little is known about its physiological functions. These may be diverse, as IDE has been localized to several locations, including the cytosol, peroxisomes, endosomes, proteasome complexes, and the surface of cerebrovascular endothelial cells.
It has first been noted for the case of insulin insufficiency in the brain of Alzheimer's patients. Because of that Alzheimer's disease has been called "Type 3 diabetes" and the insulin modification therapies are currently in pharmaceutical's pipelines.
Recent studies suggest an association between insulin resistance and AD (fat cell sensitivity to insulin can decline with aging): In clinical trials, a certain insulin sensitizer called "rosiglitazone" improved cognition in a subset of AD patients; in vitro, beneficial effects of Rosiglitazone on primary cortical rat neurons have been demonstrated.
On 9/13/2011 it was announced that a form of inhalable insulin, aerosolized insulin, applied deep into the nostrils may delay the onset of Alzheimer's disease.
Source: Wikipedia (All text is available under the terms of the GNU Free Documentation License and Creative Commons Attribution-ShareAlike License.)