In the summer of 1982, seven heroin users were admitted to a California hospital paralyzed and mute. They were in their 20s, otherwise healthy — until a synthetic drug they had manufactured in makeshift labs left them frozen inside their own bodies. Doctors quickly discovered the cause: MPTP, a neurotoxic contaminant that had destroyed a small but critical part of the brain, the substantia nigra, which controls movement.

The patients had developed symptoms of late-stage Parkinson’s, almost overnight.

The cases shocked neurologists. Until then, Parkinson’s was thought to be a disease of aging, its origins slow and mysterious. But here was proof that a single chemical could reproduce the same devastating outcome. And more disturbing still: MPTP turned out to be chemically similar to paraquat, a widely used weedkiller that, for decades, had been sprayed on farms across the United States and Europe.

For a young Dutch doctor named Bas Bloem, the story would become formative. In 1989, shortly after finishing medical school, Bloem traveled to the United States to work with William Langston, the neurologist who had uncovered the MPTP-Parkinson’s link. What he saw there reshaped his understanding of the disease — and its causes.

https://archive.ph/DgsFC