In this thread on another board I've listed some of the evidence supporting the use of Low Carbohydrate eating regimes either to prevent, delay or slow the progress of dementia.

It is still very early days in this research area but as one of the first detectable changes in brain chemistry linked to Alzheimers is a decrease in brain glucose metabolism in the area linked to memory, abnormal sugar metabolism and the development of Alzheimer's is something that needs watching.

If we are going to help people with Alzheimer's stabilise their condition or better still prevent the onset of the condition, surely the best way is to correct insulin resistance in the body/brain by reducing dependence on refined carbohydrates and preventing leptin resistance by reducing high fructose corn syrup and other excessive fructose consumption. Alongside that strategy insulin resistant brains need an alternative fuel source such as ketone bodies that can be encouraged by the consumption of coconut oil or other Medium Chain Triglyceride (MCT) oil.