In BACE-ball and your brain I discussed how energy shortages in the brain tend to increase the activity of an enzyme (BACE1) that speeds up the activation of APP (amyloid precursor protein). This increases the formation of A-beta (for beta amyloid), which is associated with the development of Alzheimer disease. Thus, energy brownouts are to be avoided at all costs. Dr. Robert Vassar, the lead author of this insightful article, linked deficits in energy generation in the brain with the development of narrowing of the arteries to the brain. Oxygen and nutrients such as the major brain fuel glucose are delivered to nerve cells via the circulatory system. When blood flow is restricted, these vital compounds don't get where they need to go and brain cells suffer. One result is impaired energy generation and activation of BACE1.
Another interesting paper that relates to this very issue was recently published in the medical journal Brain Research (1226 (2008): 209-219). It further investigates the connection between power brown outs in the brain and A-beta formation. The investigations were performed in very old dogs who spontaneously produce A-beta in their brains.
The authors noted that localized declines in cerebral glucose metabolism are an early and progressive feature of Alzheimer disease. They state that such declines occur long before symptoms develop and, as such, offer a window of time for medical intervention. Medium chain triglycerides (MCTs) are rapidly turned into ketone bodies in the liver and ketones are used efficiently in the brain as an optional fuel source. Noting this, they provided a nutritional product (MCT oil) that can generate this alternative fuel (ketones) for the brain when glucose is in short supply or is not being used efficiently. In their study, dogs were supplemented with MCT oil for several months and brain metabolism was subsequently investigated.
They documented that aged dogs receiving the MCT therapy showed markedly improved mitochondrial (mitochondria are the small intra-cellular inclusions that generate energy) function. The effect was most prominent in the parietal lobe region. This is where early decreases in glucose use tends to occur in patients with Alzheimer disease. APP levels also decreased. There was also a trend towards a decrease in total A-beta in the parietal lobes of the treated dogs.
What this tells us is that energy generation was improved and with it APP and A-beta levels fell. These results are consistent with the hypothesis that brain cell energy failure (an inciting cause of Alzheimer disease) can trigger the buildup of A-beta, which ultimately leads to neurodegeneration. Furthermore, they suggest that by supplying another fuel source for the neurons to use, the process can be reversed with beneficial results. The take home message might be that for anyone at risk for such diseases, that chronic supplementation with MCT oil might be a prudent preventative intervention.