Niggs- in fact- 30 of 79 patients were on no levodopa prior to the study- analysis of extensor rigidity showed no association between any meds-doses- and the halt in the progression of flexor rigiditiy- the authors postulate that he laxatives either improve the "dysbiosis"- altered bowel bacteria that may be intrinsic tio PD or by improving the constipation (which is definitely intrinsic toi PD) and affect the dysbiosis indirectly- either way they postulate that the altered flora are associated with an immune/inflammatory response that helps improve the disease itself!