The researchers used data from the US and Canadian governments, as well as discussions on Reddit, to come to their conclusion. They found that Beijing starting to shut down Chinese companies that were supplying Mexican criminal groups with precursor chemicals to fentanyl in 2023 was associated with the decline in fentanyl deaths. In other words, a major supply chain disruption, which started long before Trump started his second term, was likely behind the decline. “It’s not a straight line between drug supply and overdose deaths because of protective behaviors that have been adopted in between,” he told WaPo. More on fentanyl: Experts Puzzled as Drug Overdose Deaths Suddenly Start Dropping