The Brain That Meth Built, and the Drug That’s Starting to Fix It

Russell Campillo remembers the first time he used methamphetamine. He describes it in a 2022 essay published in Missouri Medicine — the first time in his life he could sit down and read a book from cover to cover, the first time he could make art without the weight of everything else pressing down. “For most of us,” he wrote, “meth is an energy you’ve never had.” Then it wasn’t energy anymore. It was the condition of existing. Then came the job loss, the homelessness, the hallucinations that arrived after nights without sleep, the teeth that deteriorated while he was paying attention to everything except his own body. He was, by his own account, in a place where sobriety seemed statistically improbable. Studies he would later cite in his peer education work put the odds of long-term recovery without formal rehabilitation at approximately 5 percent. He became one of the 5 percent.

His story is not exceptional. It is a precise illustration of what methamphetamine does to the brain — and why, for thirty years, medicine had nothing to offer people like him except behavioral therapy and the hope that will plus support would be enough.

The Dopamine Problem

Methamphetamine works by flooding the brain’s reward circuitry with dopamine — not the modest pulse that eating a good meal or completing a task produces, but a surge roughly twelve times larger than cocaine generates, concentrated in the nucleus accumbens and prefrontal cortex. The immediate effect is what Campillo described: heightened focus, euphoria, the sense of capability. The problem is what happens to the dopamine system afterward.

Chronic methamphetamine use downregulates dopamine receptors. The brain, attempting to maintain homeostasis against the repeated flood, reduces its own sensitivity to the signal. When someone stops using, the dopamine system doesn’t snap back to baseline — it functions at a deficit, sometimes for months or years. The clinical experience of this is what researchers call dysphoria during early abstinence: the absence of ordinary pleasure, the flatness of normal experience, the craving that is not just psychological habit but a neurological gap the brain is trying to fill.

This mechanism is why the standard addiction medicine toolkit has historically failed people with methamphetamine use disorder. Opioid use disorder can be treated with medications that target opioid receptors directly — buprenorphine, methadone, naltrexone. Alcohol use disorder has several pharmacological options that reduce craving and withdrawal. Methamphetamine use disorder has none. The stimulant treatment gap has been one of the most persistent failures in addiction medicine, and it is not for lack of understanding the problem. The dopamine system is well-mapped. The intervention has been elusive.

Until recently, the best-validated treatment for methamphetamine use disorder has been contingency management — a behavioral intervention that uses structured financial or tangible incentives (gift cards, prizes, vouchers) for drug-negative urine screens and treatment attendance. It works because it provides an external dopamine signal, a real reward that substitutes, temporarily, for the neurological reward the drug used to deliver. Contingency management has the strongest evidence base of any stimulant treatment. It is also, in the United States, not available under most insurance plans, is not widely accessible in rural areas, and has faced political resistance from legislators who characterize paying people to stay sober as morally problematic.

ADAPT-2 and What 16.5 Percent Means

The ADAPT-2 trial — Accelerated Development of Additive Pharmacotherapy Treatment — was a Phase 3, randomized, double-blind, placebo-controlled study of the combination of extended-release injectable naltrexone and oral bupropion for adults with moderate or severe methamphetamine use disorder. It is, to date, the most rigorous pharmacological trial ever conducted for this indication.

The headline result: 16.5 percent of participants in the naltrexone-bupropion arm achieved the primary response criteria (three of four negative drug screens in weeks five and six of the six-week treatment phase) compared to 3.4 percent in the placebo arm. In the overall trial across two sequential stages, the response rate was 13.6 percent versus 2.5 percent for placebo.

In the overall trial across two sequential stages, the response rate was 13.6 percent versus 2.5 percent for placebo.

Reported outside of context, 16.5 percent sounds like a low bar. It is not a low bar. It is a meaningful clinical signal in a disease with no established pharmacological treatment, in a population where, as Russell Campillo’s peer education data shows, spontaneous remission without formal intervention is rare. A secondary analysis published in the Journal of Addiction Medicine in March 2026 — led by Manish K. Jha and Madhukar H. Trivedi at UT Southwestern — went deeper, examining craving and impulsivity as mediators of treatment response across 357 participants.

What Jha and Trivedi found was specific and mechanistically meaningful: naltrexone, working on the opioid receptor pathway, significantly reduced cue-induced craving — the kind that fires when someone sees a pipe or a bag or a neighborhood associated with past use. Bupropion, acting on dopamine and norepinephrine systems, alleviated the dysphoria of early abstinence, giving the brain something to work with neurochemically during the period when the dopamine system is at its most depleted. The combination worked, in their analysis, not because either drug was doing the same thing but because they were addressing two different aspects of the same underlying problem: the craving that pulls toward relapse, and the flatness that makes staying away feel impossible.

Elevated impulsivity showed an additive effect independent of craving levels — meaning people with high impulsivity and high craving were at compounded risk of returning to use, and the medication combination addressed both signals through separate mechanisms. This is the kind of nuanced finding that matters for how clinicians should be thinking about patient selection, dosing, and adjunctive support.

No FDA approval exists yet for this combination in methamphetamine use disorder. The Phase 3 primary completion is expected in October 2026. The regulatory timeline after that is uncertain. But the evidence base is no longer empty.

What the Brain Needs to Recover

The research on what recovery looks like for people with methamphetamine use histories — documented in a qualitative study by the Recovery Research Institute — is a corrective to the narrow clinical framing of “abstinence as endpoint.” People in recovery from methamphetamine describe recovery across multiple domains simultaneously: housing stability, mended family relationships, employment or purposeful activity, mental health management, and a sense of being able to participate in ordinary life again.

This is consistent with what the neuroscience would predict. The dopamine deficit of early abstinence is real but not permanent. PET scan studies have shown dopamine receptor density recovering toward baseline over 14 months of sustained abstinence — the brain’s plasticity reasserting itself given time and the absence of the drug’s disruption. The implication is that treatment support during that recovery window is critical: the window is real, recovery is possible, and the support structures that keep someone stable during the 14 months of neurological restoration are not incidental to recovery — they are the treatment.

For Campillo, that meant peer support, professional certification, and work that required him to be present for other people. For JJ Keller — a peer recovery specialist who last used methamphetamine roughly five years ago after a final dose sent him into a psychotic state while homeless in New York — it meant the care he received at a Brooklyn hospital during that crisis, which became the turning point, and which he has since used to shape how patients are received in the Denver-metro recovery programs where he now works.

Neither Campillo nor Keller had access to naltrexone-bupropion combination therapy. The medication wasn’t available to them. But their recoveries trace the same contours that the ADAPT-2 data describes: the role of craving reduction, the importance of getting through early abstinence without the brain simply demanding the drug back, and the community scaffolding that makes neurological restoration possible.

The 30-Year Gap and What Fills It

The absence of FDA-approved pharmacological treatment for methamphetamine use disorder is not just a clinical problem — it is a policy-funding problem, a treatment-recovery access problem, and a moral problem. The populations most affected by methamphetamine use disorder — rural communities, LGBTQ+ populations with disproportionately high prevalence, people in the criminal justice system — have been told, implicitly, that their condition doesn’t merit the pharmacological investment that opioid use disorder has received.

The ADAPT-2 results don’t fill the 30-year gap. They point toward filling it. The FDA approval process will take years, and the barriers to Medicaid coverage of combination injectable naltrexone therapy — the cost, the administration requirements, the prior authorization bureaucracy — will add more years beyond that. Contingency management, already evidence-proven, still faces the “paying people” objection in state legislatures even as five states have now secured CMS approval for Medicaid-funded programs.

Contingency management, already evidence-proven, still faces the “paying people” objection in state legislatures even as five states have now secured CMS approval for Medicaid-funded programs.

Russell Campillo describes himself as “one of the 5 percent” — the people who achieve long-term sobriety without formal rehabilitation. He does not celebrate that. He uses it as a number that names the problem: the other 95 percent need the treatment system to work, and for three decades, it had almost nothing to offer them for the specific mechanics of stimulant recovery.

The ADAPT-2 trial is not the end of that sentence. But it is the first time the sentence has started to change.