← Huberman Lab

The Effects of Cannabis (Marijuana) on the Brain & Body

Episode 92 Oct 3, 2022 2h 38m 19 insights
In this episode, I discuss cannabis (aka marijuana), including the biological mechanisms underlying its effects on the mind and body, its known medical applications, its impact on libido, creativity, hunger, hormones and more. I also cover the known adverse health consequences of chronic and even acute (one-time) use and the factors that determine if cannabis is helpful or harmful. Additionally, I detail how the various strains of cannabis: sativa, indica and hybrid strains, can produce such divergent effects depending on the strain type, THC-to-CBD ratio, total dosage, and frequency of use. I review why cannabis can impact speech patterns and one’s propensity to develop anxiety/depression during and after use and, in some individuals, paranoia. As the legal landscape for cannabis is rapidly evolving, this episode should interest a wide audience, including former/current cannabis users, those in the medical, sports, law enforcement, and educational communities and, of course, children, teenagers, and parents. For the full show notes, visit hubermanlab.com.
Actionable Insights

1. Avoid Cannabis During Pregnancy

Pregnant or lactating mothers should absolutely avoid ingesting or smoking cannabis, THC, or CBD products, as these compounds are critical for fetal brain wiring and development and can cross the blood-placental barrier.

2. Youth Avoid Cannabis Use

Individuals aged 14-25 should avoid cannabis use (smoking, vaping, edibles) due to its detrimental effects on the developing brain, including accelerated thinning of the prefrontal cortex, increased risk of anxiety, depression, and psychosis later in life.

3. Assess Psychosis Predisposition

Individuals with a pre-existing genetic propensity for psychosis, schizophrenia, or bipolar disorder should be extremely cautious or avoid cannabis entirely, as it can significantly increase the risk of psychotic episodes.

4. Avoid Smoking/Vaping Cannabis

Regardless of the substance, smoking or vaping cannabis severely impairs endothelial cells in blood vessels, decreasing cognitive capacity, increasing stroke risk, impacting lung function, and leading to sexual dysfunction.

5. Youth Cannabis Cessation & Recovery

If a young person (14-25) has used cannabis, quitting immediately and focusing on healthy behaviors like cardiovascular exercise, adequate nutrition, avoiding nicotine, sufficient sleep, and social connection can facilitate some recovery of brain function.

6. Chronic Use Increases Anxiety

Chronic cannabis use (twice a week or more) can paradoxically increase anxiety and depression over time, even for individuals who initially used it for anxiety relief, as the body’s cannabinoid receptor systems habituate.

7. High Potency THC Risk

Higher potency THC concentrations are directly associated with a greater risk of developing psychosis, major depressive episodes, or major anxiety disorders later in life, especially with chronic use.

8. Don’t Increase Dose for Paranoia

If a specific strain or edible causes paranoia or anxiety, increasing the dosage is categorically false advice and will likely exacerbate the negative effects rather than alleviate them.

9. Understand Cannabis Dependence

Regular cannabis use can lead to dependence because external cannabinoids (THC/CBD) out-compete natural endogenous cannabinoids, causing heightened anxiety and disrupted mood when not ingested.

10. Know Local Cannabis Laws

It is your obligation to know the local laws regarding cannabis possession, use, and sale in your area and when you travel, as legality varies tremendously.

11. Beware “Natural” Fallacy

Do not mistakenly assume that because cannabis is a plant and naturally occurring, or because the body has cannabinoid receptors, that ingesting cannabis is inherently safe or appropriate for you.

12. Effects Vary Individually

There is no reliable way to predict how a specific cannabis strain or dosage will affect an individual, as responses can vary greatly even among people with similar personality traits.

13. Understand THC:CBD Ratios

Learn about Type 1 (THC dominant), Type 2 (equal THC:CBD), and Type 3 (CBD dominant) strains to better understand and potentially predict how different cannabis products might impact you.

14. Cannabis Alters Speech Patterns

Chronic cannabis users (twice a week or more) often experience changes in speech production, including reduced spectral tilt (vocal effort/intensity) and altered verbal timing, even when not under the influence.

15. Cannabis & Sexual Arousal

Cannabis’s effect on sexual arousal depends on individual prolactin response; if cannabis elevates your prolactin, it will likely suppress sexual desire, whereas if it doesn’t, it may increase arousal.

16. Question Cannabis Safety Claims

Be critical of the perception that cannabis is universally safe or beneficial, especially as its legality increases, as this often overlooks documented negative health effects, particularly for young people.

17. Ensure Proper Hydration

Maintain optimal brain and body function by ensuring proper hydration and adequate electrolyte intake (sodium, magnesium, potassium), as even slight dehydration impairs performance.

18. Daily Element Electrolyte Routine

Dissolve one packet of Element in 16-32 ounces of water first thing in the morning and during any physical exercise to ensure adequate hydration and electrolyte balance.

19. Utilize Waking Up App

Use the Waking Up app for meditation, mindfulness training, Yoga Nidra, or NSDR (non-sleep deep rest) sessions, even short 10-minute ones, to restore cognitive and physical energy and explore different brain states.