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Peter Attia MD220 ‒ Ketamine: Benefits, risks, and promising therapeutic potential | Celia Morgan, Ph.D.
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CHAPTERS
- 0:02 – 1:58
Celia Morgan’s research path: psychosis model work and recreational ketamine users
Peter Attia asks Celia Morgan about her training and how her PhD became centered on ketamine. She describes a dual research focus: ketamine’s acute effects as a model for psychosis and observational work with recreational users in the UK, including neuroimaging studies conducted during time at Yale.
- •Celia Morgan studied psychology with pharmacology and did her PhD at University College London, with research time at Yale.
- •Her early ketamine work predated its modern use as an antidepressant.
- •Ketamine was studied as a laboratory model to probe cognitive changes resembling psychosis.
- •She simultaneously studied recreational ketamine use, which was a significant issue in the UK at the time.
- 1:58 – 3:17
Ketamine’s origins and why it became a widely used anesthetic
The conversation turns to ketamine’s history as an anesthetic synthesized in the 1960s as a replacement for PCP. Morgan explains why ketamine’s unusual emergence phenomena (hallucinations and out-of-body experiences) limited routine use despite its broad global role, and Attia highlights its clinical appeal in conscious sedation because it lacks respiratory depression.
- •Ketamine was synthesized as an anesthetic replacement for PCP, aiming to avoid PCP’s prolonged psychosis-like effects after anesthesia.
- •Morgan notes ketamine still acts primarily at the NMDA receptor but is less potent than PCP.
- •Clinicians observed unusual recovery experiences (hallucinations, out-of-body sensations), limiting routine use.
- •Attia emphasizes ketamine’s advantage of minimal respiratory depression, especially relevant for conscious sedation.
- •Morgan notes ketamine is widely used globally and appears on the WHO essential medicines list.
- 3:17 – 7:49
Where ketamine is used: pediatrics, geriatrics, and battlefield/low-resource settings
Attia and Morgan discuss ketamine’s physiologic safety profile and how that shaped its use in children and in trauma settings. Morgan adds context on its use in developing countries and in battlefield medicine, and both reflect on the broader mystery of anesthesia and consciousness.
- •Attia notes ketamine doesn’t lower blood pressure and can be advantageous in trauma and shock; Morgan agrees it can even raise blood pressure slightly.
- •Morgan says ketamine is used routinely in pediatrics, though she’s unsure whether children report fewer hallucinations or are simply more accepting of altered states.
- •Morgan highlights ketamine’s utility where intubation resources are limited, supporting its prominence in developing countries.
- •Morgan mentions ketamine’s extensive use in Vietnam War battlefield medicine.
- •They briefly discuss how anesthesia relates to consciousness and how it’s measured (e.g., EEG-based indices).
- 7:49 – 14:01
Neurobiology basics: glutamate, GABA, NMDA receptors, and how ketamine may work
Attia asks for a foundational explanation of excitatory and inhibitory neurotransmission. Morgan outlines glutamate’s role in excitation and learning (including long-term potentiation) and GABA’s inhibitory effects, then describes competing theories for ketamine’s action—direct NMDA blockade versus indirect glutamate increases via GABAergic interneurons.
- •Morgan explains glutamate as the brain’s major excitatory neurotransmitter and the NMDA receptor’s role in learning/memory and long-term potentiation.
- •GABA is described as inhibitory, dampening neural signaling; Attia gives alcohol and benzodiazepines as relatable examples of GABA potentiation.
- •Morgan explains dangerous withdrawal physiology from inhibitory substances like alcohol/benzodiazepines due to rebound excitation, including seizure risk.
- •Ketamine’s mechanism is presented as not fully resolved: it may block NMDA receptors directly on glutamatergic neurons and/or on GABAergic interneurons.
- •Blocking NMDA receptors on inhibitory interneurons could produce a net increase in glutamate flow (disinhibition).
- 14:01 – 17:41
Dose-dependent subjective effects and accident risk at high dissociative doses
Morgan describes how ketamine effects change dramatically with dose, from stimulation to perceptual distortions to profound dissociation and catatonia. She emphasizes that while lethal overdose is uncommon, ketamine can create severe vulnerability to accidents, sharing tragic examples such as drowning due to deep dissociation.
- •Ketamine has markedly different effects across dosing ranges, from mild intoxication to profound dissociation.
- •Morgan describes high-dose states as cataleptic/catatonic outwardly while internally vivid and hallucinatory.
- •She notes ketamine users become vulnerable to accidents at high doses, citing drowning in a bathtub as an example.
- •Attia compares the behavioral danger to LSD-like risk (harm via altered behavior), while Morgan stresses ketamine’s deeper functional impairment and vulnerability.
- •Morgan introduces bladder epithelial toxicity as a consequence seen with repeated, heavy high-dose use.
- 17:41 – 22:07
Administration routes and scheduling history; ketamine vs other psychedelics and MDMA classification
The discussion covers ketamine’s common medical route (IV), alternative routes (IM, sublingual, intranasal, oral), and why intranasal became prominent. They then move into regulation timelines and compare ketamine’s legal medical status with Schedule 1 psychedelics, including a brief exchange on whether MDMA is a psychedelic.
- •Morgan says IV is the best-characterized medical route and the basis for much research; IM has good bioavailability; intranasal was popularized by users and later licensed in a depression product.
- •Oral dosing is noted as easier but less bioavailable; Attia asks about first-pass effects and toxicity, and Morgan says oral toxicity work is not well characterized yet.
- •Ketamine was scheduled in the US in the late 1990s; Morgan mentions scheduling changes in the UK and that it was banned for human use in Russia at one point.
- •Attia contrasts ketamine’s legal medical use with LSD/psilocybin/MDMA being Schedule 1 in the US.
- •Attia describes MDMA as an empathogen rather than a classic psychedelic; Morgan notes policy paradoxes given ketamine’s abuse potential.
- 22:07 – 28:02
Addiction potential and harms: dependence rates, tolerance, bladder damage, and ketamine-seeking patterns
Attia presses for how addictive ketamine is relative to opioids and benzodiazepines. Morgan explains that dependence definitions vary and offers her study estimate of dependence/craving symptoms among recreational users, then details severe harms from heavy daily use—rapid tolerance, extreme dosing, and bladder injury—while distinguishing these patterns from medical dosing.
- •Morgan estimates about 9% of a recreational-user sample showed symptoms of dependence/craving, while emphasizing measurement challenges.
- •She says ketamine dependence is observed in a small subset, and medical-trial data so far suggest low observed dependency in depression treatment contexts.
- •Morgan details severe bladder toxicity in heavy daily users, including cases requiring bladder removal in young people.
- •She describes rapid tolerance (tachyphylaxis), with heavy users functioning on doses that would incapacitate others.
- •Attia raises concern about ketamine clinics and ketamine-seeking across locations; Morgan notes case reports and argues for better registries.
- 28:02 – 33:05
Why people escalate ketamine use; notable narratives and PCP ‘lore’ vs evidence
Morgan describes motivations reported by users, from cost and escapism to chasing insight, and recounts published stories of extreme ketamine addiction and related tragedies. Attia asks why PCP had a reputation for violence and “bulletproof” behavior, and Morgan argues much of that is lore without strong literature support, possibly shaped by policing and social factors.
- •Morgan reports user motivations ranging from “cheap and gets me very high” to pursuit of altered consciousness and perceived insights.
- •She references accounts of extreme ketamine use, including continuous IV use described by a neuroscientist and another narrative ending in fatal exposure after dissociation.
- •Morgan emphasizes rapid tolerance as a driver of dose escalation.
- •Attia asks about PCP’s aggressive reputation; Morgan says she finds little supporting evidence for “bulletproof” phenomena in literature.
- •Morgan suggests policing practices and social context may have contributed to PCP narratives; she notes PCP is not commonly a UK street drug.
- 33:05 – 35:37
Ketamine vs LSD/psilocybin: different receptor targets, anxiety profile, and why abuse may be easier
Attia asks how ketamine compares with classical psychedelics. Morgan contrasts ketamine’s NMDA/glutamatergic action with 5-HT2A psychedelics and discusses differences in cognition, dissociation, and emotional tone—especially ketamine’s relative lack of anxiety even during intense experiences—which they link to its higher abuse potential.
- •Morgan contrasts ketamine’s glutamatergic/NMDA mechanism with LSD/psilocybin’s 5-HT2A mechanism.
- •Both note a shared phenomenon of ego dissolution, with Morgan saying ketamine can produce it profoundly.
- •Morgan says people can often think more clearly on LSD/psilocybin, while ketamine impairs higher cognitive functions more.
- •Morgan notes ketamine’s analgesia/anxiolytic feel: experiences can sound scary but often lack strong physiological anxiety; LSD/psilocybin can be terrifying depending on dose/setting.
- •Attia and Morgan suggest ketamine’s more predictable emotional “escape” may reduce negative feedback and facilitate repeated use.
- 35:37 – 39:44
How ketamine became a depression treatment: early IV trials and rapid response
Attia explains how ketamine first came to his attention through off-label intranasal prescribing and the rise of ketamine clinics. Morgan traces the modern evidence base to early IV work in treatment-resistant depression, highlighting the major shift from delayed-onset antidepressants to ketamine’s rapid symptom reduction.
- •Attia recounts early exposure to off-label intranasal ketamine and later proliferation of ketamine clinics.
- •Morgan references early, less central historical psychiatric uses, then focuses on a pivotal study in 2000 giving a single ketamine infusion to treatment-resistant depression patients.
- •Ketamine’s standout feature is rapid reduction in depressive symptoms compared with delayed-onset traditional antidepressants.
- •The early depression protocol discussed is IV ketamine at 0.5 mg/kg infused over about 40 minutes.
- •Morgan emphasizes these were treatment-resistant, not mild depression, populations.
- 39:44 – 47:58
Acute experience variability, predictors, and whether “trippy” effects relate to antidepressant benefit
They discuss how therapeutic dosing compares to recreational dosing and how subjective effects vary widely even with weight-adjusted infusions. Morgan reviews emerging predictors and explains that evidence is mixed on whether dissociation predicts antidepressant response, with some indication that more nuanced measures (including ineffable or “mystical” features) may better relate to outcomes.
- •Morgan estimates recreational “blast off” doses as variable but often higher than therapeutic infusion dosing; intranasal is common recreationally.
- •She describes large inter-individual variability at 0.5 mg/kg: some feel mildly intoxicated, others experience vivid, bizarre hallucinations.
- •Morgan notes limited predictors; she mentions findings linking family history of alcohol problems with greater therapeutic response but less acute response, and BMI relating to acute effects.
- •She says more suicide attempts may be associated with better therapeutic response in depression, possibly reflecting severity.
- •Evidence on acute dissociation predicting antidepressant effects is mixed; Morgan says some studies find a link, many do not, and better instruments may be needed.
- •Morgan describes using recorded narratives and machine learning to detect patterns that might predict outcomes.
- 47:58 – 56:45
What response looks like in depression: onset, response rates, and the maintenance dilemma
Morgan describes striking rapid improvements in some severely depressed patients, likening it to people “coming alive,” but stresses many do not respond and effects often fade within days to weeks. They discuss how this creates pressure toward repeated dosing and maintenance models, especially with intranasal ketamine, while questioning long-term strategies and the need for better real-world data.
- •Morgan says some patients feel markedly better quickly, with increased clarity and renewed interest in the world.
- •She estimates a substantial non-response rate and notes that early high response rates often decline as more studies emerge.
- •Morgan describes typical duration as roughly two days to a week for many, sometimes up to two weeks, with high variability.
- •They discuss repeated dosing and maintenance patterns, including intranasal ketamine regimens with ongoing use over long periods.
- •Morgan argues for better registries to understand real-world dosing patterns, safety, and outcomes, especially given broad clinic-based use.
- 56:45 – 1:05:12
Mechanisms and brain effects: plasticity windows, default mode network, and prediction error disruption
Morgan outlines one leading framework: ketamine triggers downstream cascades increasing synaptic plasticity, which may open a window for learning and therapeutic change. She discusses timing hypotheses from animal work, her team’s EEG efforts to map this in humans, and neuroimaging concepts including default mode network disruption and altered prediction error signaling.
- •Morgan describes ketamine (and other compounds) as potentially increasing synaptic plasticity in the prefrontal cortex, linked to antidepressant effects.
- •She references animal-timing concepts: plasticity changes beginning hours after dosing and peaking around a day later, motivating therapy timing outside the acute intoxication period.
- •Morgan notes a limitation: neuroplasticity is not unique to therapeutic drugs; she gives cocaine as an example where plasticity may relate to addiction.
- •She explains the default mode network as resting-state/background brain activity, often linked to rumination and affected by psychedelics and mindfulness.
- •Morgan describes research on prediction error signaling and dorsolateral prefrontal cortex disruption under ketamine, making predictable events feel surprising and vice versa.
- •Attia asks about metabolism and regional effects; Morgan suggests the picture is not fully clear and notes increases in prefrontal glutamate are discussed in the field.
- 1:05:12 – 1:16:39
Overuse risks and long-term concerns: cognition, hippocampal changes, and daily-dose drug development
Attia raises concerns about chronic high-frequency ketamine use and subtle cognitive/affective changes beyond bladder toxicity. Morgan describes observed cognitive impairments and neuroimaging findings in heavy daily users, and she expresses concern about pharmaceutical efforts toward daily ketamine dosing and escalation risks due to tolerance.
- •Attia worries about long-term high-frequency ketamine use and describes a perceived “vacancy” or dullness in heavy users, beyond bladder damage.
- •Morgan describes cognitive impairments (including planning) observed in heavy daily ketamine users and reduced hippocampal function/volume findings in imaging work.
- •Morgan contrasts the original promise of ketamine as not necessarily a maintenance medication with the reality of prolonged dosing in some settings.
- •She reports concern about trends toward daily dosing development and the implication of inevitable dose escalation due to tolerance.
- •Attia criticizes profit-driven expansion without sufficient consideration of downsides and notes the challenge of separating placebo effects in clinic contexts.
- 1:16:39 – 1:26:12
Ketamine-assisted treatment for alcohol (and other addictions): trial design, results, and therapy content
Morgan explains her alcohol dependence work, including the rationale for using ketamine with structured psychological therapy to extend benefits. She details a four-arm trial comparing ketamine and therapy combinations, describes high abstinence rates, and outlines how therapy sessions are timed around infusions to leverage a hypothesized post-ketamine learning window.
- •Morgan notes historical Russian work using ketamine plus psychotherapy in addictions and discusses limitations of older study designs while highlighting reported long-term reductions.
- •She describes her four-arm trial comparing ketamine plus therapy, ketamine plus education control, placebo plus therapy, and placebo plus education control.
- •Morgan reports strongest outcomes in the ketamine-plus-therapy group, including high abstinence rates at six months, with ketamine-plus-education next best.
- •She explains the education control included alcohol education and relaxation to control for therapist time and nonspecific support.
- •Placebo was saline, and Morgan acknowledges an active placebo (e.g., midazolam) might have improved blinding.
- •Morgan describes therapy timing: a session before infusion, then a longer session the next day, repeated across three infusions, plus structured homework (planning, journaling, mindfulness for cravings, identifying risky situations and cognitive biases).
- 1:26:12 – 1:36:06
Clinical safeguards and scaling to healthcare systems: screening, contraindications, and phase-three plans
Morgan outlines screening requirements and exclusion criteria used in her trials, emphasizing abstinence readiness, psychiatric contraindications, and blood pressure concerns. She then discusses adapting therapy intensity for a state healthcare system and explains why the next larger trial will simplify arms and use low-dose ketamine as a control to manage expectancy and retention.
- •Trial entry requires substantial screening and often medically supervised detox to ensure safe abstinence before starting treatment.
- •Morgan lists exclusions including psychosis (or first-degree relative history), uncontrolled hypertension due to ketamine’s blood pressure effects, and other medical contraindications.
- •An anesthetist supervises infusions; Morgan notes rare cases where infusion is stopped due to high blood pressure spikes.
- •Morgan designed therapy to be manualized and feasible within a state healthcare system rather than requiring extremely intensive therapist hours.
- •For the larger phase-three study, they will compare the most clinically relevant extreme arms and avoid giving ketamine without a “therapeutic container.”
- •They plan to use a very low ketamine dose as the control to improve expectancy management and reduce dropout from perceived placebo assignment.
- 1:36:06 – 1:42:40
Guidance and cautions for real-world ketamine use: supervision, therapy integration, and safety concerns with at-home models
Attia asks how Morgan would caution people in a US landscape of easily accessible ketamine clinics. Morgan argues ketamine is best used within therapy, with minimal necessary dosing, and she warns against unsupervised at-home use due to profound dissociation and safety risks, also noting concerns about product variability via analogs.
- •Morgan recommends embedding ketamine use within psychotherapy rather than “just doing ketamine,” to avoid unnecessary high numbers of doses and to support patient empowerment.
- •She cautions against models that provide ketamine with inadequate clinical supervision, especially unsupervised at-home use where accidents or emergencies could occur during dissociation.
- •Morgan emphasizes ketamine’s dissociative nature makes supervision important even if abuse risk is limited by cost in some settings.
- •When discussing non-medical use, Morgan stresses harm reduction basics: safe setting, sober supervision, and starting with small doses.
- •She notes ketamine can sometimes be substituted with or confused for ketamine analogs (e.g., methoxetamine), which may have greater bladder toxicity, reinforcing the need for caution.
