How THC and CBD work together in the brain – new study

New findings on how CBD and THC – the psychoactive compound in cannabis – affect the brain when administered together, could help to develop new cannabinoid therapeutics, scientists say.

A study has investigated the impact on the brain of CBD and THC, both as separate entities and when co-administered.

Researchers at University College London (UCL) analysed data from previous studies, including one which used functional Magnetic Resonance Imaging (fMRI) technology to measure brain activity in participants taking CBD and THC.

For the first time, they explored the response of the striatum region of the brain – a major part of the motor and reward systems. This is a critical component of numerous aspects of cognition, including motor and action planning, decision-making and motivation.

One study compared inhaled cannabis containing 8 mg THC, 8 mg THC + 10 mg CBD and a placebo. It showed strong disruptive effects of both THC and THC + CBD on connectivity in the associative and sensorimotor networks.

However it also identified a “specific effect of THC” in the limbic striatum network which was not present in the THC + CBD condition.

In a second study, testing oral 600 mg CBD versus placebo, CBD increased connectivity in the associative network, but produced only relatively minor disruptions in the limbic and sensorimotor networks.

The study concludes that THC “strongly disrupts striato-cortical networks” but that this effect is mitigated by the co-administration of CBD.

It states: “Oral CBD administered has a more complex effect profile of relative increases and decreases in connectivity.

“The insula [part of the brain implemented in diverse functions including emotions and self-awareness] emerges as a key region affected by cannabinoid-induced changes in functional connectivity, with potential implications for understanding cannabis-related disorders, and the development of cannabinoid therapeutics.”

This is the first report in human subjects of data from THC, THC + CBD and CBD use achieved “using a unified set of analysis methods, and with all comparisons performed in a placebo-controlled, double-blind design”.

Read the full report here.

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