Mark Hyman, MD · 2025-07-16 · Mark Hyman (host), Robin Carhart-Harris
Why Your Brain is Stuck: The Truth About Psychedelics and Plasticity
37 research-tied claims examined: 2 contradicted 3 overstated 27 supported 5 unverified
3 Overstated
Depression is the leading cause of disability, loss of quality-adjusted life years, and societal cost.
"Depression is the biggest source of disability and loss of quality of life years, and cost to society." (said at 0:01:40)
While major depressive disorder is often highlighted by the World Health Organization as a leading contributor to global disability and non-fatal health loss, asserting that it is the single biggest source of disability, loss of quality/disability-adjusted life years (DALYs), and societal cost across all health conditions is overstated. In comprehensive epidemiological assessments such as the Global Burden of Disease Study 2019, depressive disorders rank among the top ten leading causes of burden (e.g., sixth in DALYs among adults aged 25–49), but conditions such as ischemic heart disease, stroke, and low back pain rank higher overall in total DALYs and years lived with disability (YLDs).
- contradicts: Global burden of 369 diseases and injuries in 204 countries and territories, 1990-2019: a … (Lancet (London, England) 2020) · cited 19775x in the literature
"Five of the causes that were in the top ten for ages 10-24 years were also in the top ten in the 25-49-year age group: road injuries (ranked first), HIV/AIDS (second), low back pain (fourth), headache disorders (fifth), and depressive disorders (sixth). In 2019, ischaemic heart disease and stroke were the top-ranked causes of DALYs in both the 50-74-year and 75-years-and-older age groups." (abstract, results, passage verified)
pubmedfull study (doi) - context: Global, regional, and national burden of 12 mental disorders in 204 countries and territor… (The lancet. Psychiatry 2022) · cited 5980x in the literature
"GBD 2019 showed that mental disorders remained among the top ten leading causes of burden worldwide, with no evidence of global reduction in the burden since 1990." (abstract, conclusions, passage verified)
pubmedfull study (doi)
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.
- supports: Modulation of Serum Brain-Derived Neurotrophic Factor by a Single Dose of Ayahuasca: Obser… (Frontiers in psychology 2019) · cited 177x in the literature
"After treatment (D2) we observed higher BDNF levels in both patients and controls that ingested ayahuasca ( N = 35) when compared to placebo ( N = 34)." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Low Doses of LSD Acutely Increase BDNF Blood Plasma Levels in Healthy Volunteers. (ACS pharmacology & translational science 2021) · cited 136x in the literature
"The findings demonstrated an increase in BDNF blood plasma levels at 4 h (5 μg) and 6 h (5 and 20 μg) compared to that for the placebo. The finding that LSD acutely increases BDNF levels warrants studies in patient populations." (abstract, results, passage verified)
pubmedfull study (doi) - contradicts: Effects of psychoplastogens on blood levels of brain-derived neurotrophic factor (BDNF) in… (Molecular psychiatry 2025) · cited 17x in the literature
"We included 29 studies and found no evidence that psychoplastogens elevate peripheral BDNF levels in humans (SMD = 0.024, p = 0.64). This result was not affected by drug, dose, blood fraction, participant age, or psychiatric diagnoses. In general, studies with better-controlled designs and fewer missing values reported smaller effect sizes." (abstract, results, passage verified)
pubmedfull study (doi)
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.
Unverified means no publication matching the claim was located; it does not prove the claim false. Spotted an error? See the corrections policy - disputes from the people quoted are prioritized.