Stanford PD Community Blog

This recent “Washington Post” article is about the “gut-first” hypothesis of Parkinson’s disease (PD) — the idea that a high percentage of PD cases start in the gut and that abnormal protein spreads from the gut to the brain.  Evidence is that constipation can begin more than a decade before motor symptoms of PD.  And abnormal proteins can be found almost the whole length of the digestive tract.   

On March 20, 2026, the U.S. Food and Drug Administration (FDA) issued a safety warning that requires products containing carbidopa/levodopa to carry new labeling which warns about the potential for Vitamin B6 (pyridoxine) deficiency. The warning guides physicians and other health care professionals to test for baseline vitamin B6 levels (with a blood test) prior to starting patients on treatment with carbidopa/levodopa therapies and periodically while on treatment and to supplement with vitamin B6 as necessary. Of note – it is important that patients do not take vitamin B6 on their own without monitoring blood levels, since vitamin B6 levels that are too high can be dangerous as well.

A newly released report, co-sponsored by the American Parkinson Disease Association, has shown that Parkinson’s disease (PD) and atypical Parkinsonism are placing an $82.2 billion annual economic burden on the United States as of 2024—highlighting the growing financial strain of these neurological conditions.

Gastrointestinal (GI) difficulties can be among the most bothersome of the non-motor symptoms caused by Parkinson’s disease (PD). Constipation, which involves the slowing down of the large intestine or lower gut is the most common of the GI symptoms, affecting 80-90% of people with PD.

Author Rachel Reid, whose novels were adapted into the “Heated Rivalry” TV series, was diagnosed with Parkinson’s disease in 2023. She said in a video on social media, “When good things happen, sometimes the universe hands you some worse stuff to balance it out and for me that’s been that my Parkinson’s symptoms have gotten a bit worse and it’s made it difficult physically to write. I’m definitely a lot slower and that’s just something I need to learn how to navigate and kind of face instead of ignoring.”