The Numbers Are Good. The Explanation Is Contested.

For the first time in a decade, the direction is right. Drug overdose deaths in the United States peaked at approximately 109,000 in 2022. They fell in 2023. They fell again in 2024 — by 27%, the largest single-year decline ever recorded in the dataset. Provisional CDC data released in May 2026 projects 69,973 deaths for the 12 months ending December 2025 — a number that represents roughly 40,000 people who are alive today and wouldn’t be if the peak rate had held.

Nobody disagrees this is good news. What is contested is why — and the answer matters, because the policy debate about harm reduction, treatment access, and supply interdiction is being waged on the premise that the dominant explanation justifies the dominant prescription.

Supply disruption: the leading academic case

The strongest academic argument for why deaths fell points outside U.S. borders. Starting around 2021, China enacted regulatory restrictions on precursor chemicals used to synthesize illicitly manufactured fentanyl. Research from the Center for International and Security Studies at Maryland concluded that the overdose decline was “likely driven not by changes in domestic treatment or prevention efforts, but by a disruption in the global supply of illicit fentanyl.” DEA seizure data tell the same story: fentanyl purity, which had risen sharply during the Covid-19 pandemic, began declining after 2022. The drug reaching U.S. markets became not just harder to obtain but weaker per unit.

A December 2025 preprint went further, arguing that decreased fentanyl potency — not expanded harm reduction services — was “the primary driver of the decline.” If that finding survives peer review, it substantially complicates the narrative that harm reduction programs deserve primary credit.

The supply disruption theory carries an obvious and unsettling implication: if supply disruption caused the decline, supply disruption can be reversed. Precursor restrictions in China are regulatory, not physical. New supply chains can be established. New synthetic opioids — nitazenes, for instance, which are already appearing in U.S. drug supply reports — can fill a potency gap. A decline driven by supply shock is a fragile decline.

Harm reduction and treatment: the converging-forces case

The competing view, articulated by Keith Humphreys of Stanford in Health Affairs in March 2026, emphasizes the cumulative effects of multiple simultaneous domestic policy shifts. Naloxone became available over the counter in 2023. The X-waiver for buprenorphine prescribing was eliminated the same year, dramatically expanding the number of clinicians who could legally prescribe it. Billions in opioid settlement funds began flowing to state and local programs. Harm reduction infrastructure expanded — more syringe service programs, more test strip distribution, more peer support workers reaching people in crisis.

Humphreys and others point to the timing: the sharpest declines correlate with the period when these policy changes took effect. Correlation is not causation, but the alignment is not coincidental. And the domestic-factors argument has a structural strength the supply-disruption thesis lacks: it names mechanisms that are controllable and buildable. Supply chains that China restricts can be rebuilt; buprenorphine infrastructure, once established, compounds.

The neuroscience that links both theories

There is a neurochemical layer to this debate that often gets missed in policy coverage, and it explains why supply changes translate so directly to overdose rate changes.

Fentanyl is approximately 100 times more potent than morphine at the mu-opioid receptor. That extraordinary affinity means the margin between a dose that produces the desired effect and a dose that causes fatal respiratory depression is very narrow. When fentanyl potency is high and variable — which it has been throughout the illicit supply’s expansion — even a person with significant opioid tolerance is at risk. Tolerance builds through chronic exposure by downregulating mu-opioid receptor density and adapting the cAMP signaling pathway. The person’s brain has calibrated itself to one level of opioid signal. A batch that is 20% stronger than expected overwhelms that calibration. The tolerance that protects against a “normal” dose provides no margin of safety against a more potent batch.

When fentanyl potency is high and variable — which it has been throughout the illicit supply’s expansion — even a person with significant opioid tolerance is at risk.

This is why fentanyl potency reduction — whether from supply disruption or from test strips that allow people to detect unexpectedly high concentrations — directly reduces overdose risk. And it is why defunding fentanyl test strip programs at this particular moment is a gamble. The supply disruption is not permanent. New analogs will emerge. When they do, the infrastructure that was dismantled to score a policy point will not come back online quickly enough to meet them.

What the decline doesn’t tell us

The 69,973 projection for 2025 is meaningful progress. It is not a solved problem. For context: deaths from HIV/AIDS in the United States peaked at approximately 50,000 in 1995 and now run approximately 12,000 annually — the result of decades of sustained investment in research, treatment infrastructure, and harm reduction. The overdose crisis is closer to the HIV peak than to the HIV-controlled baseline.

A 27% single-year decline is remarkable. It is not a reason to ease pressure on the systems that are keeping people alive during the decline — and it is certainly not a reason to defund the programs that are part of what’s working. The overdose crisis has produced false dawns before: the shift from prescription opioids to heroin in the mid-2010s, the emergence of illicitly manufactured fentanyl in 2016, the arrival of xylazine as an adulterant in 2020. Each time, the supply adapted faster than the public health infrastructure.

The question for 2026 is whether the policy environment will sustain the gains the data shows or squander them before they become durable. That question does not have an obvious answer right now.

What this means for treatment navigation

For Rize — and for any navigator working with people seeking treatment in Arizona — the contested nature of the overdose decline should change how we talk about it. Telling someone “things are getting better” without the context that better is fragile is not useful. What is useful: understanding that the tools associated with the decline — naloxone, buprenorphine, harm reduction infrastructure — are under funding pressure at the exact moment they appear to be working.

For someone in Arizona looking for help right now, none of this is abstract. Arizona ranks 49th in behavioral health access. The statewide decline in overdose deaths has been less pronounced than the national figure. The question is not whether the good numbers are real — they are. The question is whether they will hold.