In antipsychotic-naive first-episode psychosis patients, heavy cannabis use was associated with lower brain-derived neurotrophic factor (BDNF) levels, a relationship not seen in healthy controls.
Psychiatrists treating early psychosis, neuroscience researchers studying BDNF, and clinicians advising psychosis patients about cannabis use.
Cannabis-BDNF link found in psychosis patients but not healthy controls
What the researchers found
Among 70 drug-naive first-episode psychosis patients and 57 healthy volunteers, cannabis use was associated with reduced BDNF levels only in the psychosis group. Heavy cannabis use also correlated with younger age in patients. In healthy volunteers, cannabis use was linked to tobacco use but not to BDNF levels.
Why it matters
BDNF supports neuron health and plasticity. Finding that cannabis lowers BDNF specifically in psychosis patients suggests a biological mechanism by which cannabis may worsen outcomes in vulnerable individuals.
The numbers in context
70 first-episode psychosis patients (antipsychotic-naive). 57 healthy volunteers. High cannabis use was associated with lower BDNF in patients but not controls. High cannabis use also correlated with younger age in patients.
How the study worked
Cross-sectional study of 70 antipsychotic-naive first-episode psychosis patients and 57 healthy volunteers. Blood samples analyzed for BDNF by ELISA. Substance use, clinical diagnosis, and demographic variables collected via structured clinical interview.
What this study cannot tell us
Cross-sectional design cannot determine causation. Peripheral BDNF levels may not reflect brain BDNF. Cannabis use was self-reported. Relatively small sample sizes.
How to read the evidence
Cross-sectional study with a meaningful comparison group, but small sample and cannot establish causation.
When this study was published
2020 study. Adds to growing evidence on differential effects of cannabis in psychosis-vulnerable populations.
The bigger picture
The selective effect in psychosis patients, but not healthy volunteers, suggests that the biological context matters. The same exposure may have different neurobiological consequences depending on underlying vulnerability.
Questions still open
- Does cannabis-related BDNF reduction contribute to worse psychosis outcomes? Would BDNF levels recover if patients stopped using cannabis? Is the relationship specific to certain cannabis components like THC?
Common questions
What is BDNF?
Why were these patients antipsychotic-naive?
Read the original research
Cannabis use influence on peripheral brain-derived neurotrophic factor levels in antipsychotic-naïve first-episode psychosis.
European archives of psychiatry and clinical neuroscience, 270(7), 851-858
Citation
Toll, A; Bergé, D; Burling, K; Scoriels, L; Treen, D; Monserrat, C; Marmol, F; Duran, X; Jones, P B; Pérez-Solà, V; Fernandez-Egea, E; Mané, A. (2020). Cannabis use influence on peripheral brain-derived neurotrophic factor levels in antipsychotic-naïve first-episode psychosis.. European archives of psychiatry and clinical neuroscience, 270(7), 851-858. https://doi.org/10.1007/s00406-020-01117-y
Explore the wider topic
- How THC Affects Your Amygdala: The Brain's Threat Detector and Cannabis
- The Anandamide Connection: Your Body's Natural Bliss Molecule
- How Long for Cannabinoid Receptors to Return to Normal
- Cannabis and the Developing Brain: What Every Teenager (and Parent) Should Know
- Why Can't I Enjoy Anything Without Weed? The Science Behind It
- Dopamine Recovery After Quitting Weed: What the Science Says
- The Endocannabinoid System Explained Simply: What It Does and Why It Matters
- Your Endocannabinoid System Explained: Why Withdrawal Happens
- Your Nervous System After Quitting Weed: Fight or Flight
- Using Weed Under 18: What It Does to Your Developing Brain
- What THC Does to Your Brain: Why Withdrawal Happens
- THC and Your Prefrontal Cortex: What Cannabis Does to Your Decision-Making Brain
- Weed, Cortisol, and Stress: What Cannabis Does to Your Stress Hormones
- Weed and Memory: What the Science Says About THC and Your Hippocampus
- Weed and Motivation: Is Amotivational Syndrome Real?
- Weed and Your Nervous System: What THC Actually Does to Your Brain and Body
- How Weed Rewires Your Reward System (And How to Reset It)