After rereading my post I maybe didn't make it very clear. What presumably helped her Parkinson's were the ketones from the very low carb diet. An alternative (actually preferred) fuel for the brain. She actually also takes some BHB (betahydroxybuterate) which immediately gets converted at the liver to ketones to boost her ketone level. The diet does the majority of the work but the BHB just gives it a little kick up in the ketone levels in the blood. She is kind of experimenting with the BHB to see if she can get even a little more improvement over the extremely low carb diet.

There is research showing the brain prefers ketones and if ketones are in the blood stream the brain will hog them. It appears to prefer ketones (a baby is born in a state of ketosis and is in ketosis in the womb, so it is a completely natural state). Also Alzheimer's has been described by some as type III diabetes where the brain cells have trouble utilizing glucose as a fuel. In the case of it the brain is able to use the ketones whereas it is starving and actually losing volume because of brain cell death because it can no longer use glucose very well as a fuel source.

The heart has also shown in studies that it works more efficiently if there are ketones available to it. It pumps a higher volume of blood per beat. I don't remember how they did the test for the study but the net result was the heart operated more efficiently on ketones than glucose.

MCT (derived from coconut or palm kernel oil) are medium chain triglycerides, specifically mostly C8 and C10 (a little bit of C6 but very little). These medium chain fats do not get digested normally. Instead they get ported directly to the liver and are processed there mostly into ketones. Coconut oil also contains (the majority) of C12 which is also considered a medium chain triglyceride. It however has to go through the digestive process so any ketones it produces is in a much slower rate and is also dependent on insulin levels (which is directing where energy goes based on its level). C12 does not get ported to the liver for processing. So depending on the fed state the C12 could be either ketones or directed to fat storage if insulin levels are high. So the MTC oils for the most part are always converted into ketones. For people that are not using glucose as fuel very well, some people use these oils to raise their ketones in the blood. 

Coconut oil can be a bit hard on digestion if taken in too great of quantity. It can cause diarrhea. Best to start out slow and increase to tolerance. The C12, which is abundant in coconut oil, is the hardest on digestion. C10 is intermediate and C8 has the least stomach disturbance. C8 is the hardest and most expensive to process so costs more. It can be purchased alone or more often and more economical as a C8-C10 blend. I have used both. The gallon I have now in the pantry, and been taking a couple teaspoons full each night since back home, is a blend. The 4 months I was in Bonaire I took a couple teaspoons of coconut oil each evening right after supper.

Does it do me any good? Danged if I know. I quit taking it for quite a while and just started up again a few months ago. When I use up what I have I'm not sure I will buy any more or might just take some coconut oil (which is widely available in the grocery store and is cheap). MCT oil is not cheap. It will raise my ketone levels. I do have a meter I can check. I don't think I need it for any particular reason, just wanted to get some experience with it (in case I feel I do need it some day). I absolutely would be taking it if I had Alzheimer's or Parkinson's or any number of other non-infectious diseases. When the body is not or can not utilize glucose properly, ketones in the bloodstream are a definite benefit in my opinion. A lot of real world experience shows it is beneficial as well as some limited studies.

I got carried away. Probably more than you ever wanted to know.