There are open lines of communication between brains and bowels and, in mice at least, these channels allow an individual’s gut bacteria to steer their behaviour.
The latest evidence for this “gut-brain axis” comes from Javier Bravo at University College Cork. He fed mice with a probiotic bacterium called Lactobacillus rhamnosus, often found in yoghurts and dairy products. The bacterial menu changed the levels of signalling chemicals in the rodents’ brains, and reduced behaviours associated with stress, anxiety and depression.
... some trials have found that probiotics can help to alleviate the mood symptoms that accompany irritable bowel or chronic fatigue syndrome. To that end, Bravo wanted to see if L.rhamnosus could influence the brains of normal, healthy animals.
Bravo found that his mice, after regularly eating Lactobacillus, were more likely to spend time in the exposed parts of a maze (a common test for anxiety symptoms) than those who ate bacteria-free meals. They were also less likely to drift motionlessly when plopped into water (a common test for depressive symptoms). And during stressful situations, they built up lower levels of stress hormones.
The bacteria also boosted the role of GABA...
It may seem odd that bacteria in an animal’s gut can control what happens in its brain, on the other side of the body. But the two organs have a direct line between them – the long, branching vagus nerve, which transmits information from the gut and other visceral organs to the brain. When Bravo severed the vagus nerve in his mice, Lactobacillus lost all of its influence. It changed neither the rodents’ behaviour nor their GABA receptor levels.

http://blogs.discovermagazine.com/no...viour-in-mice/

The enteric nervous system is affected by PD, and the gut is possibly the entry point for the disease (the Braak hypothesis).

Earlier in the year I drunk 1 litre of homemade probiotic yoghurt (L. acidophilus) a day for about a month. I didn't notice any difference in my Parkinson's. Tasted great, though, but I stopped after I put on about half a stone of weight (that's 7 pounds to the Americans amongst us and 3 kilograms to just about everyone else!!!).

John

Yogurt helps me with avoiding UTI's, but I don't think it has changed my behavior. Unless, I had bad behavior with a bad UTI. :0(

I can see where this good bacteria might help in reducing stress/anxiety. It would make sense that eating unhealthy foods would cause crankiness/depression etc..
But, I would think depression would come from having a debilitating disease and/or being almost depleted of dopamine.
But, if a person eats yogurt and it helps alliviate the anxiety and depression, then that is more help to get better. So, why not eat yogurt? It is good for you and tastes good, too.
And, it should aid in digestion. Constipation causes crankiness.