Our brains make up about 2% of our body mass. It is actually a relatively small organ. However, it is very demanding and uses as much as 20% of the energy we use in a day. The demands of our brains are such that if a fly is starving, it will shut down its ability to record long-term memories. As the plaques build in the Alzheimer's brain and the brain begins to fail, it is not able to use the energy available to it.
A research project is underway to stimulate the brains of individuals with early stage Alzheimer's using Deep Brain Stimulation (DBS). Essentially, an electronic "pacemaker" is implanted so that electric pulses may directly stimulate the brain. The hope is that this will improve the the functioning of the declining brain.
Perhaps, the stimulation will assist where the natural metabolic processes have lost efficacy.