The rehydration theory in relation to PD has been proposed elsewhere, with positive results. John Coleman in Australia credits his recovery, in part, to a homeopathic rehydration therapy that was originally devised for athletes, called The Aquas. See http://www.aquas4life.com/

See John's own site http://www.returntostillness.com.au/home.php

He also pays a lot of attention to diet and meditation.

I personally know someone using the Aquas who is doing quite well though he is not rid of the disease. In any case, plenty of water intake is good for the body, and brains especially like to stay spongy.