THC and CBD had opposite effects on brain connectivity in regions involved in attention and salience processing
In healthy cannabis users, THC reduced connectivity between the prefrontal cortex and striatum while CBD enhanced it, with opposite patterns also seen in hippocampal-prefrontal connections.
Quick Facts
What This Study Found
Researchers administered THC, CBD, or placebo to healthy occasional cannabis users and scanned their brains during a task involving processing novel and salient stimuli. THC and CBD produced opposite effects on functional connectivity between brain regions central to attention and salience processing.
THC reduced connectivity between the dorsal striatum and prefrontal cortex, and this reduction was related to poorer task performance. CBD enhanced this same connection. Conversely, THC increased connectivity between the hippocampus and prefrontal cortex, while CBD reduced it.
These opposite effects on brain network communication occurred in regions involved in determining what is relevant and worth attending to, a process called salience attribution. Disrupted salience processing is a leading theory for how psychotic symptoms arise.
Key Numbers
Three conditions compared: THC, CBD, placebo. Three key brain regions analyzed: dorsal striatum, prefrontal cortex, hippocampus. THC and CBD showed opposite effects on fronto-striatal and mediotemporal-prefrontal connectivity.
How They Did This
Randomized, placebo-controlled study in healthy occasional cannabis users. Participants received oral THC, CBD, or placebo and underwent fMRI during an oddball salience processing task. Seed cluster-based functional connectivity analysis examined correlations between salience-processing brain regions.
Why This Research Matters
The finding that THC and CBD have opposite effects on brain connectivity in salience-processing regions provides a neural basis for why THC can induce psychotic-like experiences while CBD may protect against them. This has implications for understanding how different cannabis strains or ratios affect the brain.
The Bigger Picture
The psychosis theory of aberrant salience attribution proposes that psychotic symptoms arise when the brain incorrectly tags irrelevant stimuli as important. THC's disruption and CBD's enhancement of the brain connections involved in this process help explain the contrasting psychiatric profiles of these two cannabinoids.
What This Study Doesn't Tell Us
The sample included only occasional cannabis users, so results may differ in regular or heavy users. Single-dose design does not capture effects of chronic use. The study used oral administration, which differs from smoked or vaped cannabis in onset and metabolism.
Questions This Raises
- ?Would cannabis strains with higher CBD-to-THC ratios show less disruption of salience network connectivity?
- ?Could CBD be used as an adjunct treatment for psychosis by restoring salience processing?
- ?Do these connectivity changes persist after chronic use?
Trust & Context
- Key Stat:
- THC and CBD had opposite effects on fronto-striatal connectivity
- Evidence Grade:
- Randomized, placebo-controlled fMRI study in healthy volunteers. Well-designed but single-dose, single-session protocol.
- Study Age:
- Published in 2015. THC-CBD interaction research has expanded significantly since.
- Original Title:
- Cannabinoid modulation of functional connectivity within regions processing attentional salience.
- Published In:
- Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 40(6), 1343-52 (2015)
- Authors:
- Bhattacharyya, Sagnik(39), Falkenberg, Irina, Martin-Santos, Rocio(10), Atakan, Zerrin, Crippa, Jose A, Giampietro, Vincent, Brammer, Mick, McGuire, Philip
- Database ID:
- RTHC-00922
Evidence Hierarchy
Participants are randomly assigned to treatment or placebo groups to test cause and effect.
What do these levels mean? →Frequently Asked Questions
Do THC and CBD affect the brain differently?
Yes. In this study, THC reduced communication between the prefrontal cortex and striatum (important for attention) while CBD enhanced it. They also had opposite effects on hippocampal-prefrontal connections.
What is salience processing?
Salience processing is the brain's ability to determine what is important and worth paying attention to. When this process is disrupted, people may assign inappropriate significance to irrelevant stimuli, which is a feature of psychotic experiences.
Read More on RethinkTHC
- THC-amygdala-anxiety-brain
- anandamide-weed-withdrawal
- cannabinoid-receptors-recovery-time
- cannabis-developing-brain-teenagers
- cant-enjoy-anything-without-weed
- dopamine-recovery-after-quitting-weed
- endocannabinoid-system-explained-simply
- endocannabinoid-system-withdrawal
- nervous-system-weed-withdrawal-fight-flight
- teen-weed-use-under-18-effects-brain
- thc-brain-withdrawal
- thc-prefrontal-cortex-brain-effects
- weed-cortisol-stress-hormones
- weed-memory-loss-recovery
- weed-motivation-amotivational-syndrome
- weed-nervous-system-effects
- weed-reward-system-brain
Cite This Study
https://rethinkthc.com/research/RTHC-00922APA
Bhattacharyya, Sagnik; Falkenberg, Irina; Martin-Santos, Rocio; Atakan, Zerrin; Crippa, Jose A; Giampietro, Vincent; Brammer, Mick; McGuire, Philip. (2015). Cannabinoid modulation of functional connectivity within regions processing attentional salience.. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 40(6), 1343-52. https://doi.org/10.1038/npp.2014.258
MLA
Bhattacharyya, Sagnik, et al. "Cannabinoid modulation of functional connectivity within regions processing attentional salience.." Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 2015. https://doi.org/10.1038/npp.2014.258
RethinkTHC
RethinkTHC Research Database. "Cannabinoid modulation of functional connectivity within reg..." RTHC-00922. Retrieved from https://rethinkthc.com/research/bhattacharyya-2015-cannabinoid-modulation-of-functional
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.