HoldsUp

Robin Carhart-Harris

Robin Carhart-Harris is a neuroscientist specializing in psychedelic research and psychedelic psychiatry. His research investigates the neurobiological mechanisms and clinical applications of substances such as psilocybin, LSD, MDMA, DMT, and ketamine. His published work focuses on their therapeutic potential for conditions like major depressive disorder, as well as their effects on brain connectivity, neuroplasticity, and subjective experience.

25 claims checked on air: 1 contradicted 2 overstated 18 supported 4 unverified

What they said on air

2 citing their own research

0:00:36supportedvery lowWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

The first patient in the psilocybin trial who had previously failed numerous antidepressants achieved full remission and remained well.

"Our first patient had been on I don't know how many antidepressants, and this got her well and she's still well." (said at 0:00:36)

The speaker refers to the first participant enrolled in the Imperial College London open-label feasibility trial of psilocybin for treatment-resistant depression. Published records from this trial evaluated patients with moderate-to-severe major depression who had failed multiple conventional antidepressant treatments. Patients received two oral doses of psilocybin alongside psychological support, with substantial proportions achieving rapid and sustained symptom reductions and remission up to 6 months post-treatment. As this claim describes an individual outcome from an open-label, uncontrolled pilot trial, the certainty of evidence for general therapeutic efficacy remains very low.

0:05:00supportedmoderateWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

In the mid-20th century, psychedelics were used as psychotherapeutic adjuncts by public figures such as Ethel Kennedy and Cary Grant.

"During studying psychoanalysis, I discovered that psychedelics had been used in psychotherapy as tools to catalyze and deepen psychotherapy. And that was done in the mid-20th century. And it was a big thing for a while, you know, big names like Ethel Kennedy and Cary Grant had had this therapy and seemingly had benefited from it." (said at 0:05:00)

Historical and psychiatric literature documents that throughout the mid-20th century (specifically the 1950s and 1960s), psychedelics such as lysergic acid diethylamide (LSD) were extensively investigated and administered clinically as adjuncts to psychotherapy to facilitate psychotherapeutic insights and treat psychiatric conditions. Prominent figures, including actor Cary Grant, publicly documented undergoing clinical LSD-assisted psychotherapy during this era and reported personal benefit, before regulatory restrictions in the late 1960s and 1970 halted widespread clinical use.

0:11:45supportedhighWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Placebo pain relief produces measurable biological neural correlates in the brain.

"You might have a psychological response to a placebo, say it's given for pain and you experience some pain relief, and then we know in neuroscience that that process has a biological counterpart even though the mechanism on the face of it looks psychological." (said at 0:11:45)

Extensive neuroimaging research demonstrates that placebo-induced pain relief corresponds to measurable neurobiological changes in the brain. An individual participant-level fMRI meta-analysis of 20 neuroimaging studies (n = 603) found that placebo analgesia is associated with significant reductions in pain-related neural activity across multiple brain networks—including the ventral attention network (mid-insula), somatomotor network (posterior insula), thalamus, habenula, mid-cingulate cortex, and supplementary motor area—alongside increases in activity within frontoparietal networks.

0:15:05supportedmoderateWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

States of reduced consciousness such as deep sleep, coma, or general anesthesia are characterized by low brain entropy and highly predictable ongoing brain activity.

"At one far end, the end of low entropy, the lights go out, sort of literally. There's nothing there. You're knocked out with an anesthetic. You're in deep sleep. You've suffered a brain injury. You're in a coma. There's no content. And if you look at ongoing brain activity, it's very uneventful. It's very predictable. It's very low entropy." (said at 0:15:05)

Empirical measures of spontaneous brain activity across electroencephalography (EEG), intracranial recordings, and magnetoencephalography (MEG) consistently show that states of reduced or lost consciousness—such as general anesthesia, non-REM deep sleep, and severe brain injury/coma—are characterized by reduced neural signal diversity, reduced Lempel-Ziv complexity, and low entropy (reflecting more stereotypic, predictable neurodynamics) relative to normal waking consciousness.

0:16:20supportedmoderateWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

In studies published around 2017, administration of LSD, psilocybin, and psychedelic doses of ketamine was shown to increase brain entropy.

"We first saw it around 2017. We published on it with LSD, psilocybin, and also ketamine in a psychedelic-like dosage, saw brain entropy dial up under all of those compounds, and with it people's conscious experience, the subjective experience was deeper, richer, more diverse, more changeable." (said at 0:16:20)

A 2017 study by Schartner, Carhart-Harris, and colleagues evaluated measures of neural signal diversity—including entropy and Lempel-Ziv complexity—using spontaneous magnetoencephalography (MEG) in humans administered LSD, psilocybin, and sub-anesthetic (psychedelic) doses of ketamine. The investigators found significant increases in signal diversity across all three compounds compared to normal waking consciousness, with increases correlating with subjective reports of the intensity of the psychedelic experience.

0:19:00supportedmoderatetheir own paperWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Psychedelics do not shut down the default mode network, but rather cause dysregulation and irregular activity patterns within it.

"it's not that we shut off the default mode network. That's a popular in a sense myth that people like and you can get away with it, but it's not really true. You're not turning it off, you're scrambling it up. And in scrambling it up—and I say it that way because it's still very active, it's just the activity is irregular now." (said at 0:19:00)

Human neuroimaging studies confirm that psychedelics do not deactivate or 'shut off' the default mode network (DMN). Instead, acute administration of serotonergic psychedelics such as psilocybin disrupts the coordinated functional connectivity and synchronization within the DMN and between large-scale networks—characterized by reduced internal network integrity, desynchronization, and increased entropy/irregularity of activity patterns.

0:26:40supportedlowWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Psychological insight experienced during a psychedelic session strongly predicts downstream therapeutic outcomes.

"One, yes, it's psychological insight, very strong predictor of therapeutic outcomes downstream." (said at 0:26:40)

Observational and prospective psychometric studies support the claim that acute psychological insight experienced during or immediately following a psychedelic session predicts positive downstream therapeutic and psychological outcomes. Validation studies for the Psychological Insight Scale (PIS) and Psychological Insight Questionnaire (PIQ) demonstrate that psychological insight acts as a key mediator for long-term well-being and predicts unique variance in improvements in psychological flexibility, life satisfaction, and therapeutic outcomes beyond traditional measures like mystical-type effects. Because the evidence relies primarily on self-report survey data and observational designs rather than controlled experimental manipulations of insight, certainty is rated low.

0:26:54supportedmoderatetheir own paperWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Emotional release during psychedelic sessions is a key factor predicting positive clinical outcomes.

"The other one is emotional release. It's strong emotion. What What is that? What's that look like? Well, often it looks like people crying... it's a cathartic a cathartic release." (said at 0:26:54)

Clinical and prospective studies consistently show that experiencing an emotional breakthrough or emotional release (commonly measured by the Emotional Breakthrough Inventory, or EBI) during psychedelic administration is a robust predictor of subsequent clinical improvement. In a Phase II randomized trial of psilocybin for treatment-resistant depression, EBI scores had one of the strongest correlations (r = -0.637) with reductions in depression severity at 3 weeks post-treatment. Similar predictive relationships between emotional breakthrough and improvements in mental well-being and depressive symptoms have been replicated across observational and clinical datasets.

0:33:25supportedlowWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Preliminary neuroimaging and EEG data on 5-MeO-DMT indicate that it induces slow-wave brain activity in addition to psychedelic brain expansion.

"In fact, there's some data that's come through that suggests some paradoxical quality to the activity, that you also get some slow waves, which is weird. So maybe a a bit like sleep, but then a bit or a lot like a a psychedelic opening up and expansion." (said at 0:33:25)

Human electroencephalography (EEG) and preclinical local field potential (LFP) data support the claim that 5-MeO-DMT induces cortical slow waves and sleep-like electrophysiological spectral signatures alongside its psychedelic effects. A human EEG study (n=29) demonstrated amplified low-frequency oscillations and complex atypical cortical slow-wave dynamics following vaporized 5-MeO-DMT administration. Preclinical research in awake rodents similarly found that 5-MeO-DMT increases delta-band power and produces LFP spectral signatures resembling slow-wave sleep. Certainty is low due to the preliminary nature and small sample sizes of the available studies.

0:36:40supportedmoderateWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

The gold standard treatment for borderline personality disorder is a long course of psychotherapy, such as Dialectical Behavior Therapy (DBT) over approximately a year.

"You know, the the gold standard treatment for for borderline is a is a long psychotherapy, you know, year or so of psychotherapy. HOST: Yeah. DBT." (said at 0:36:40)

Comprehensive structured psychotherapy, most notably Dialectical Behavior Therapy (DBT) and Mentalization-Based Therapy (MBT), is widely recognized in clinical guidelines and systematic reviews as the first-line treatment for borderline personality disorder (BPD). Standard comprehensive DBT is designed as a one-year program involving individual therapy, group skills training, and between-session coaching. A 2020 Cochrane systematic review of 75 randomized controlled trials (4,507 participants) found that psychotherapy (most commonly DBT and MBT, with trial durations up to 36 months) significantly reduced BPD symptom severity (SMD -0.52), self-harm, and suicide-related outcomes compared to treatment-as-usual.

0:43:57supportedmoderateWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Schizophrenia is typically preceded by mood disorders like depression and anxiety.

"You know, most schizophrenia are preceded by mood disorder, depression, anxiety." (said at 0:43:57)

Published systematic reviews and longitudinal cohort studies of first-episode psychosis and clinical high-risk (CHR) / at-risk mental state (ARMS) populations confirm that the onset of schizophrenia is commonly preceded by non-specific affective and anxiety symptoms or disorders. A 2025 systematic review of prodromal presentations found that non-specific symptoms such as depression (52%), worry (41%), and anxiety (38%) are the predominant initial manifestations before attenuated psychotic symptoms emerge. Furthermore, large multicenter cohorts (such as the NAPLS 2 study) and meta-analyses show that 70% to 79% of individuals in the clinical prodrome meet criteria for comorbid Axis I psychiatric diagnoses, with depressive and anxiety disorders being the most prevalent.

0:44:45supportedhighWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Avatar therapy uses computer animation to create an image of a persecutory voice for dialogic therapy to reduce hallucination-related distress in schizophrenia.

"avatar therapy, you know, where through, um, computer animation, you can create an avatar, an image, a animated image of of the voice, the persecutory voice, tormenting voice, and and then work in dialogue to to sort of um change your relationship with this persecuting voice" (said at 0:44:45)

The claim accurately describes AVATAR therapy. AVATAR therapy uses computer software to create a digital audio-visual representation (avatar) of the patient's persecutory auditory hallucination. Through a series of facilitated sessions, the patient engages in direct dialogue with this avatar (voiced by the therapist) to alter their relationship with the persecutory voice, assert control, and reduce voice-related distress and severity. Multiple randomized controlled trials (e.g., Craig et al., 2018; Garety et al., 2024) have confirmed that AVATAR therapy significantly reduces auditory hallucination severity and voice-related distress in individuals with psychosis/schizophrenia spectrum disorders compared to supportive counselling or treatment as usual.

0:50:55supportedlowWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Robin Carhart-Harris conducted a clinical trial of psilocybin for treatment-resistant depression in 20 participants, some of whom had previously tried up to 14 antidepressant medications.

"We did that small trial, it ended up being 20 people, and saw really promising results... some people had tried 14 in in that trial, and this got her well, and she's still well." (said at 0:50:55)

Robin Carhart-Harris and colleagues at Imperial College London conducted an open-label feasibility clinical trial assessing psilocybin with psychological support in patients with treatment-resistant major depression. The initial findings in 12 patients were reported in 2016 (Lancet Psychiatry), and the expanded cohort totaling 20 patients followed for up to 6 months was published in 2018 (Psychopharmacology). All participants had moderate-to-severe unipolar treatment-resistant depression having failed multiple prior antidepressant treatments (with participants having tried up to 14 previous treatments). Marked reductions in depressive symptoms were observed following treatment, with responses maintained through 6 months of follow-up. Because the study was an open-label, uncontrolled feasibility trial (n=20), certainty regarding clinical efficacy is rated as low.

0:55:15unverifiedvery lowWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Psychologist Betty Eisner introduced the concept of the psychosocial matrix in the 1960s as a third factor alongside set and setting in psychedelic therapy.

"Back in the '60s, I believe it was a psychologist, Betty Eisner, brought in a third component, which she called matrix, the psychosocial matrix." (said at 0:55:15)

No published record matching the claim that psychologist Betty Eisner introduced the concept of the 'psychosocial matrix' (or matrix) as a third factor alongside set and setting in the 1960s was located; this does not prove the claim false.

1:02:29contradictedhighWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Lexapro works by releasing serotonin and bathing the brain in more serotonin to help take the edge off stress.

"The Lexapro will release serotonin, sort of bathe the brain in more serotonin, which helps you get by. It takes the edge off stress." (said at 1:02:29)

The speaker misstates the primary pharmacological mechanism of Lexapro (escitalopram). Escitalopram is a selective serotonin reuptake inhibitor (SSRI), not a serotonin-releasing agent. It works by binding to the serotonin transporter (SERT) and blocking the presynaptic reuptake of endogenous serotonin from the synaptic cleft, rather than stimulating or releasing serotonin directly into the brain.

1:02:42supportedmoderateWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Psychedelics directly stimulate a specific aspect of the serotonin system to promote psychological and neuroplasticity.

"But what psychedelics do is actually a more direct stimulation of a certain aspect of the serotonin system, promoting plasticity. It's definitely psychological plasticity, and probably neuroplasticity, too." (said at 1:02:42)

Classical serotonergic psychedelics (such as psilocybin, LSD, and DMT) directly stimulate the serotonin 2A (5-HT2A) receptor subtype. Activation of this specific receptor stimulates downstream intracellular signaling cascades (including BDNF/TrkB and mTOR pathways), which promote structural and functional neuroplasticity—evidenced by increased neuritogenesis, spinogenesis, and synaptogenesis—as well as psychological and cognitive flexibility.

1:03:11unverifiedvery lowWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Evidence for psychedelic-induced neuroplasticity is primarily based on rodent studies, with human evidence not yet clearly established.

"Well, in mice. But human evidence of neuroplasticity, it ain't really there yet. You know, we're working on it. We'll have some brain imaging markers of it quite soon. Um, but the whole story is based on work in little mice brains and not much else, to be honest." (said at 1:03:11)

No published record matching the claim that evidence for psychedelic-induced neuroplasticity is primarily based on rodent studies and not yet clearly established in humans was located; this does not prove the claim false.

1:05:00supportedlowWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

A diffusion tensor imaging preprint by Lyons et al. shows changes in prefrontal white matter tracts following a single dose of psilocybin.

"Lyons, L-Y-O-N-S, et al. And there we show through diffusion tensor imaging, looking at the white matter tracts of the brain, that there are some changes after a single dose of psilocybin. So let's see if that replicates, of course, but it's a super exciting finding. Prefrontal tracts changed." (said at 1:05:00)

A placebo-controlled, within-subjects neuroimaging study by Lyons et al. (subsequently published in Nature Communications) evaluated 28 psychedelic-naive healthy participants before and one month after a single 25 mg dose of psilocybin versus active placebo. Diffusion tensor imaging (DTI) demonstrated decreased axial diffusivity bilaterally in prefrontal-subcortical white matter tracts at one month post-dose. The certainty is graded as low due to the small, exploratory sample size and need for independent replication.

1:05:16overstatedmoderateWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Peripheral BDNF levels can be detected in blood and are observed to increase after psychedelic use.

"The BDNF, yeah, you can pick it up peripherally in the blood and and see it go up." (said at 1:05:16)

BDNF is readily measurable in peripheral blood (serum and plasma), and some early, small clinical trials reported increases in circulating BDNF following administration of low-dose LSD or ayahuasca. However, a 2025 systematic review and meta-analysis encompassing 29 human studies on psychoplastogens and classic psychedelics found no statistically significant evidence of peripheral BDNF elevation overall (SMD = 0.024, p = 0.64), noting that higher-quality, well-controlled studies generally showed smaller or null effects.

1:05:25supportedlowWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

An open-label trial at UCSF by Ellen Bradley and Josh Woolley found improvements in motor symptoms from psilocybin in Parkinson's disease patients.

"Well, there's a trial at at UCSF looking at psilocybin for Parkinson's. It's just been published, actually. Ellen Bradley, Josh Woolley, and colleagues, really good work, really promising. It was a simple design, open-label, so there's no placebo control. So, we need to be careful at this stage about extrapolating too much. They did see improvements even in motor symptoms." (said at 1:05:25)

An open-label pilot trial conducted by Ellen Bradley, Josh Woolley, and colleagues evaluated psilocybin therapy in 12 individuals with Parkinson's disease and mood dysfunction. In addition to improvements in depression and anxiety, the study observed statistically significant post-treatment improvements in Parkinson's motor symptoms as measured by the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS Part II and Part III), sustained up to one month post-treatment. As the speaker noted, the study was an uncontrolled open-label pilot trial (n=12), limiting certainty.

1:06:07unverifiedvery lowWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Psilocybin has not worked well for Alzheimer's disease because patients cannot remember their experience or trip.

"Alzheimer's, you know, there's been a little bit of work. People can't remember their trip. They can't remember the experience, and so it hasn't worked that well so far." (said at 1:06:07)

No published record matching the claim that psilocybin has failed or proved ineffective in Alzheimer's disease because patients cannot remember their psychedelic experience was located; this does not prove the claim false. Published literature on psilocybin and other psychedelics in Alzheimer's disease remains largely exploratory, comprising preclinical studies, narrative reviews, and theoretical rationales focusing primarily on biological mechanisms (such as 5-HT2A agonism, neuroplasticity, BDNF signaling, and anti-inflammatory effects) and preliminary management of comorbid neuropsychiatric symptoms.

1:07:38supportedhighWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Clinical trial evidence to date shows underwhelming efficacy for psychedelic microdosing.

"the evidence to date is a little underwhelming for microdosing. And part of the issue is that the trials have been limited, really. There haven't been many. And when they've been done, they haven't often dosed for long enough, in my view." (said at 1:07:38)

Randomized placebo-controlled trials, systematic reviews, and meta-analyses evaluate psychedelic microdosing (primarily low-dose LSD or psilocybin) as demonstrating underwhelming efficacy beyond placebo. Blinded clinical trials show minimal to no significant improvements over placebo for mood, depression, anxiety, stress, executive function, or ADHD symptoms. Furthermore, reviews highlight that the literature remains constrained by a limited number of controlled studies with small sample sizes, brief intervention periods, and relatively few doses administered.

1:13:08overstatedmoderateWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Close to 10,000 or more people have participated in regulated adult-assisted magic mushroom experiences in states like Oregon.

"At the moment, we have in Oregon, and also Colorado is opening up, yeah, adult-assisted, uh, magic mushroom experiences essentially. And, uh, I think it's close to 10,000 people, if not more, have gone through that" (said at 1:13:08)

Statewide administrative data from the Oregon Psilocybin Services (OPS) Public Dashboard shows that during its inaugural full year of regulated operations, 5,935 clients participated across 5,375 sessions. While participation has been substantial, the claim of 'close to 10,000 people, if not more' overstates the documented number of participants in the state-regulated program.

1:15:04supportedmoderateWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Human life expectancy and longevity increased reliably following the acceptance of germ theory in the 19th century.

"germ theory, when when did that come around? 18 something or other, middle of the 19th century. And and then it was only really after that that lifespan—I know there are a few factors, you know, better dissemination of knowledge—but lifespan longevity is going up quite reliably." (said at 1:15:04)

Historical demographic and economic literature confirms that before the mid-19th century, human life expectancy fluctuated without sustained upward trends, typically averaging below 40 years. Following the mid-to-late 19th-century emergence and acceptance of the germ theory of disease—alongside associated public health, sanitation, and medical developments—life expectancy and population health began a sustained, reliable upward trajectory through the late 19th and 20th centuries.

1:17:47unverifiedvery lowWhy Your Brain is Stuck: The Truth About Psychedelics and Pl

Jack Gallant's research team at UC Berkeley has used brain decoding algorithms on neuroimaging data to predict what movies individuals are watching or what audio scripts they are listening to.

"People like Jack Gallant at UC Berkeley have used that approach to predict, um, what people are viewing in terms of movie watching, um, what people are listening to in terms of audio scripts." (said at 1:17:47)

No published record matching Jack Gallant's research team at UC Berkeley using brain decoding algorithms on neuroimaging data to predict what movies individuals are watching or what audio scripts they are listening to was located; this does not prove the claim false.

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