Stanford PD Community Blog

Two neurologists say environmental risks are a major culprit. Take action to help protect your brain today

Parkinson’s disease can affect anyone, it’s true. Your personal risk is based on a combination of your genes and environmental factors. But having certain genes that raise risk doesn’t guarantee you’ll one day have the disease. More than just a disease that simply “happens” to you, mounting evidence suggests that the progressive neurodegenerative condition is largely driven by risk factors that — with a little knowledge and planning — can be minimized.

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.