Cannabis Extract With CBD Boosted Auditory Brain Responses While Pure THC Alone Did Not | Research

The takeaway

A standardized cannabis extract containing both THC and CBD enhanced auditory processing brain responses at central electrodes, while pure THC did not, suggesting CBD may counteract some of THC's cognitive effects.

Read this if you're interested in how CBD might modify THC's effects on brain function.

Cannabis extract with CBD enhanced auditory brain responses; pure THC did not

What the researchers found

In a double-blind, placebo-controlled crossover study, 22 healthy volunteers received either pure THC, a standardized cannabis extract containing both THC and CBD, or placebo on separate occasions.

The cannabis extract (THC + CBD) produced significantly greater mismatch negativity (MMN) amplitudes at central brain electrodes compared to both placebo and pure THC. MMN is an automatic brain response that reflects auditory information processing and is often reduced in schizophrenia.

Pure THC alone did not significantly alter MMN amplitudes compared to placebo. Since the main difference between the two active conditions was the presence of CBD in the extract, the authors suggested that CBD may contribute to enhanced cortical activation and cognitive processing, potentially through neuroprotective or anti-psychotic mechanisms.

MMN amplitudes at central electrodes correlated with blood levels of 11-OH-THC, a psychoactive THC metabolite.

Why it matters

Reduced MMN is a biomarker of schizophrenia and reflects impaired automatic auditory processing. This study provided experimental evidence in humans that CBD may counteract some of THC's effects on brain function, supporting the hypothesis that CBD has neuroprotective or antipsychotic properties.

The numbers in context

22 healthy volunteers. Cannabis extract with CBD significantly increased MMN amplitude at central electrodes (p significant). Pure THC showed no significant effect on MMN. 11-OH-THC levels correlated with MMN amplitudes at central electrodes.

How the study worked

This was a prospective, double-blind, placebo-controlled crossover study in 22 healthy volunteers. Each participant received THC, standardized cannabis extract (THC + CBD), and placebo on separate occasions. Auditory mismatch negativity was recorded using 32-channel EEG with 1000 standard (1000 Hz) and deviant (1500 Hz) stimuli.

What this study cannot tell us

The sample was small (22 participants). The study examined only one aspect of cognitive function (auditory mismatch negativity). The cannabis extract contained other compounds besides CBD that could contribute to the difference. Acute effects may not predict chronic use outcomes.

How to read the evidence

This is a well-designed double-blind crossover RCT, though the small sample (22) and single cognitive measure limit generalizability.

When this study was published

Published in 2007. Subsequent research has further explored CBD's potential antipsychotic and neuroprotective properties in larger studies and clinical populations.

The bigger picture

This study contributed to the growing evidence that CBD modulates THC's effects on the brain. It was part of a broader research program exploring why cannabis with higher CBD content may be associated with fewer psychotic-like effects, a finding with implications for both recreational cannabis policy and medical cannabis formulation.

Questions still open

Does CBD's enhancement of auditory processing extend to other cognitive domains? Would these results hold in people with psychotic disorders? What is the optimal THC:CBD ratio for preserving cognitive function?

Common questions

What is mismatch negativity (MMN)?

MMN is an automatic brain response that occurs when the brain detects a sound that differs from a repeated pattern. It reflects pre-attentive auditory processing and working memory. MMN is typically reduced in schizophrenia.

Does this mean CBD makes cannabis safer?

This study found one specific brain measure was better with CBD present than without it, but a single measure doesn't capture all of cannabis's effects. However, this adds to evidence suggesting CBD may counteract some of THC's negative cognitive impacts.

Read the original research

Acute effects of Delta9-tetrahydrocannabinol and standardized cannabis extract on the auditory evoked mismatch negativity.

Schizophrenia research, 97(1-3), 109-17

View on PubMed ↗

Citation

Juckel, Georg; Roser, Patrik; Nadulski, Thomas; Stadelmann, Andreas M; Gallinat, Jürgen. (2007). Acute effects of Delta9-tetrahydrocannabinol and standardized cannabis extract on the auditory evoked mismatch negativity.. Schizophrenia research, 97(1-3), 109-17.