Confidence in faecal transplants would be increased or decreased if the following hypothesis could be proved or disproved.

Hypothesis: rather than Parkinson's causing constipation (as I'd always assumed), it is rather the case, that with the wrong bugs in the gut, Parkinson's and constipation reinforce one another: Parkinson's slows the transit time, leaving longer for toxins to build up, leading to a worsening of the Parkinson's, and so on.

If this hypothesis were correct, we would expect to find that:
- once the body has recovered from the stress of defecation, symptoms would fall to a minimum and then increase progressively until the next defecation. (It could be that the effect of years of damage swamp the short term effects);
- the probability distribution of the time between defecations is U-shaped. (The hypothesis would suggest that you have a period of reduced symptoms when the chances of going again are good, but if this opportunity is missed it gets harder and harder to go, until eventually the issue is forced.)

Has anyone got any data or references?

John