Introduction: The Neuroplasticity Rationale for Ketamine in Addiction
Substance use disorders (SUDs) remain among the most challenging conditions in contemporary psychiatry and neuroscience, characterized by compulsive drug seeking and consumption despite adverse consequences, high relapse rates, and limited pharmacological treatment options. Ketamine-assisted therapy for substance use disorders has emerged as a novel intervention grounded in the convergence of two therapeutic mechanisms: ketamine's capacity to induce rapid synaptic plasticity and its potential to catalyze psychological insight when combined with structured psychotherapeutic frameworks (Dakwar et al., 2019). This dual mechanism -- neurobiological and psychological -- distinguishes ketamine from conventional addiction pharmacotherapies that primarily target receptor occupancy or neurotransmitter reuptake.
The neurobiological basis for addiction involves maladaptive plasticity within the mesocorticolimbic reward circuitry, encompassing the ventral tegmental area (VTA), nucleus accumbens (NAc), prefrontal cortex (PFC), and amygdala. Chronic substance exposure produces enduring alterations in glutamatergic and dopaminergic signaling, dendritic morphology, and gene expression that collectively sustain compulsive drug-seeking behavior (Kalivas and Volkow, 2005). The hypothesis that ketamine -- through NMDA receptor blockade and subsequent BDNF-mTORC1-mediated synaptogenesis -- could "reset" maladaptive synaptic configurations within these circuits has generated considerable research activity across multiple substance use domains.
Mechanistic Foundations
Glutamatergic Dysregulation in Addiction
Glutamate signaling undergoes profound reorganization during the development and maintenance of addiction. In the core pathway model proposed by Kalivas (2009), chronic drug exposure produces a hypoglutamatergic state in the NAc due to downregulation of the cystine-glutamate antiporter (xCT/SLC7A11) and glial glutamate transporter (GLT-1/EAAT2). This tonic glutamate deficit paradoxically coexists with exaggerated phasic glutamate release from PFC projections to the NAc during drug cue exposure, creating a pathological signal-to-noise ratio that drives compulsive drug seeking.
NMDA receptors within the NAc and VTA undergo subunit composition changes following chronic drug exposure, with increased incorporation of GluN2B subunits that alter receptor kinetics and calcium signaling dynamics (Bhatt et al., 2015). These NMDA receptor adaptations are implicated in the incubation of drug craving -- the progressive strengthening of cue-induced craving that occurs during abstinence. Ketamine's preferential antagonism of GluN2B-containing receptors positions it to specifically target this pathological receptor adaptation.
Memory Reconsolidation and Extinction
A separate but complementary mechanistic pathway involves ketamine's potential effects on drug-associated memory processes. Drug-related memories -- cue-substance associations encoded through Pavlovian and instrumental conditioning -- are maintained through periodic reconsolidation, a process requiring NMDA receptor activation and protein synthesis (Nader et al., 2000). Pharmacological disruption of reconsolidation can destabilize and weaken drug memories, reducing their capacity to trigger craving and relapse.
Ketamine's NMDA receptor antagonism may interfere with reconsolidation of drug memories when administered in temporal proximity to cue exposure, though this hypothesis remains largely untested in human addiction populations. Additionally, ketamine may enhance the extinction of drug-cue associations by promoting plasticity in prefrontal circuits that support extinction memory formation and retrieval -- analogous to its proposed mechanism in anxiety disorders (Das et al., 2019), published in Nature Communications.
Clinical Evidence by Substance Type
Alcohol Use Disorder
The most robust clinical evidence for ketamine in SUDs comes from studies of alcohol use disorder (AUD). Krupitsky and colleagues (2007), in a landmark study published in Journal of Psychopharmacology, conducted a randomized controlled trial comparing ketamine-assisted psychotherapy (KPT) with an active control condition in 111 detoxified alcohol-dependent patients. The KPT group received a single intramuscular ketamine session (2.0 mg/kg -- a higher, psychedelic-range dose) combined with structured existential psychotherapy. At one-year follow-up, the KPT group demonstrated significantly higher rates of total abstinence (65.8% versus 24.0%) and longer time to first relapse. Notably, this study employed doses exceeding the sub-anesthetic range typically used in depression research, reflecting a distinct therapeutic paradigm that leverages ketamine's psychological effects.
More recently, Dakwar and colleagues (2020) reported results from a proof-of-concept randomized controlled trial at Columbia University, published in The American Journal of Psychiatry, examining sub-anesthetic intravenous ketamine (0.71 mg/kg over 52 minutes) combined with motivational enhancement therapy (MET) versus midazolam control with MET in 40 adults with AUD. The ketamine group demonstrated significantly higher rates of abstinence from alcohol during the 21-day post-infusion follow-up period (absolute difference of approximately 30 percentage points). Notably, ketamine appeared to enhance the psychological processes targeted by MET, including motivation for change and abstinence self-efficacy.
Cocaine Use Disorder
Dakwar and colleagues (2014, 2017) have conducted a series of investigations examining ketamine for cocaine dependence. In an initial randomized trial published in Molecular Psychiatry, 20 cocaine-dependent individuals received single infusions of ketamine (0.5 mg/kg) or midazolam as active placebo. Ketamine reduced cocaine self-administration in a laboratory choice paradigm and increased motivation to quit cocaine use at 24-hour follow-up. A subsequent 48-hour follow-up study (Dakwar et al., 2017) demonstrated that ketamine reduced cue-induced craving -- a critical relapse trigger -- with effect magnitudes exceeding those observed with any previously studied pharmacological intervention.
The most recent trial by Dakwar and colleagues (2022), published in JAMA Psychiatry, represents the largest controlled study to date. In this randomized trial, 55 adults with cocaine use disorder received five infusions of ketamine or midazolam over two weeks, combined with mindfulness-based relapse prevention. The ketamine group showed significantly greater end-of-treatment abstinence rates and reduced craving. This study is notable for its integration of repeated dosing with a structured psychotherapeutic framework, reflecting the emerging paradigm of ketamine-assisted therapy rather than ketamine monotherapy.
Opioid Use Disorder
The application of ketamine in opioid use disorder (OUD) presents unique pharmacological complexities, given ketamine's own interactions with the opioid system via mu and kappa receptor modulation. Krupitsky and colleagues (2002) conducted an early randomized trial of KPT in heroin-dependent individuals in Russia. Participants receiving existential psychotherapy combined with ketamine (2.0 mg/kg, intramuscular) demonstrated higher abstinence rates and longer time to relapse compared with a low-dose ketamine control group at two-year follow-up.
More recently, the potential role of ketamine in managing acute opioid withdrawal has attracted attention. Sub-anesthetic ketamine infusions during medically supervised withdrawal may attenuate withdrawal symptom severity through NMDA receptor-mediated modulation of noradrenergic hyperactivity -- a key neurobiological substrate of withdrawal (Jovaisa et al., 2006). A pilot study by Lalanne and colleagues (2016) in Journal of Substance Abuse Treatment reported that adjunctive ketamine during buprenorphine-assisted detoxification reduced withdrawal severity scores and improved patient comfort during the acute withdrawal period.
Tobacco Use Disorder
A randomized controlled trial by Dakwar and colleagues (2023) examined ketamine for tobacco cessation, combining intravenous ketamine with behavioral counseling. Preliminary results suggested enhanced quit rates in the ketamine group relative to active control, though the study was powered primarily to assess feasibility and safety. The rationale for ketamine in tobacco dependence parallels the alcohol and cocaine literature -- modulation of cue-reactivity, enhancement of motivational processes, and facilitation of behavioral change through synaptic plasticity augmentation.
The Psychotherapeutic Integration Model
Ketamine-Assisted Psychotherapy Paradigm
A distinguishing feature of the ketamine addiction literature is the emphasis on psychotherapeutic integration -- the deliberate combination of ketamine administration with structured psychological interventions. This paradigm operates under the assumption that ketamine's therapeutic value in addiction derives not solely from its neurobiological effects but from the synergy between pharmacologically enhanced neuroplasticity and psychotherapeutically guided behavioral change (Kolp et al., 2014).
The psychotherapeutic approaches combined with ketamine have included existential psychotherapy (Krupitsky et al., 2007), motivational enhancement therapy (Dakwar et al., 2020), mindfulness-based relapse prevention (Dakwar et al., 2022), and cognitive-behavioral relapse prevention. Each framework aims to leverage the window of enhanced psychological flexibility and receptivity that accompanies ketamine's acute and sub-acute effects -- including reduced defensive avoidance, heightened emotional insight, and increased motivation for change.
Psychological Mechanisms of Action
The psychological processes hypothesized to mediate ketamine's anti-addictive effects include enhanced mystical-type experiences (as measured by the Mystical Experience Questionnaire), increased sense of meaning and purpose, reduced craving automaticity, and strengthened commitment to behavioral change. Aust and colleagues (2020) found that the intensity of mystical-type experiences during ketamine sessions correlated with subsequent reduction in alcohol craving, suggesting that the psychological quality of the ketamine experience itself -- not merely the pharmacological exposure -- contributes to therapeutic outcome, published in Frontiers in Psychiatry.
Safety and Abuse Potential Considerations
The use of a drug with intrinsic abuse potential to treat addiction disorders raises obvious concerns. Ketamine is classified as a Schedule III controlled substance and has well-documented recreational misuse patterns. The clinical addiction literature has addressed this concern through several strategies: supervised administration only (no take-home doses), limited number of sessions, concurrent psychotherapeutic engagement, and exclusion of individuals with active polysubstance use or history of ketamine/dissociative misuse.
Across published controlled trials in SUD populations, rates of adverse events have been comparable to those observed in depression studies, with transient dissociation, nausea, and hemodynamic changes representing the most common effects. Importantly, no published trial has reported emergence of ketamine-seeking behavior or new ketamine use disorder in study participants. However, the relatively short follow-up periods in most studies (weeks to months) limit the ability to detect delayed emergence of problematic ketamine use patterns (Jones et al., 2018).
Current Limitations and Future Directions
The evidence base for ketamine in SUDs, while growing, has significant limitations. Most trials have been small, single-site, and of limited duration. The heterogeneity of dosing regimens (ranging from sub-anesthetic intravenous infusions to high-dose intramuscular injections), psychotherapeutic frameworks, and outcome measures across studies complicates synthesis and generalization. Multi-site randomized controlled trials with standardized protocols, longer follow-up periods, and health economic analyses are needed to establish the clinical utility and cost-effectiveness of ketamine-assisted therapy for addiction.
Future research priorities include identifying biomarkers predictive of treatment response, optimizing the number and timing of ketamine sessions relative to psychotherapy, determining whether sub-anesthetic doses are sufficient or whether higher psychedelic-range doses are necessary for addiction populations, and developing maintenance strategies for sustaining initial treatment gains. The intersection of ketamine pharmacology with memory reconsolidation paradigms -- combining ketamine with cue exposure to disrupt drug memories -- represents a particularly promising translational research direction.
Conclusion
Ketamine-assisted therapy for substance use disorders represents a paradigm that integrates rapid-acting pharmacology with structured psychotherapeutic intervention. Clinical trial evidence across alcohol, cocaine, and opioid use disorders demonstrates preliminary efficacy for reducing substance use, craving, and relapse, with effects that appear to be enhanced by concurrent psychotherapy. The field is at a critical juncture, with early promise now requiring validation through larger, multi-site trials and careful examination of long-term safety and durability. If confirmed, ketamine-assisted therapy could represent a transformative addition to the addiction treatment landscape.
References
- NIDA: National Institute on Drug Abuse — Federal research institute supporting science on drug use and addiction
- SAMHSA: Substance Abuse and Mental Health Services Administration — Federal agency providing treatment locators, resources, and guidance for substance use disorders
- PubMed: Ketamine for the Treatment of Addiction: Evidence and Potential Mechanisms — Review of clinical evidence and neuroplasticity mechanisms for ketamine in addiction treatment
- PubMed: Ketamine Treatment for Alcohol Use Disorder: A Systematic Review — Systematic review of ketamine efficacy specifically for alcohol use disorder
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