Research Projects

Investigating the Psychological Effects of THC and the Medical Potential of CBD

Dr. Paul Morrison, Institute of Psychiatry, London
Dr. James Stone, Imperial College, London
Amanda Feilding, Beckley Foundation, Oxford

Along with Paul Morrison from the Institute of Psychiatry (IoP) and James Stone the Beckley Foundation is investigating the effects of cannabinoids in healthy people. The focus has been on the most significant compounds found in cannabis, THC and cannabidiol (CBD). Accumulating evidence suggests that THC and CBD act on the same physiological systems in a diametrically opposed fashion. This might explain why CBD has anti-psychotic properties, whereas THC has been associated with the induction of acute psychosis. (Morrison et al. 2009).

We used EEG to study the effects of cannabinoids on electrical activity in the brain. In contrast to fMRI, EEG can resolve brain-signalling events within the millisecond range. Modern EEG methods focus on synchronised activity between brain areas, which are believed to underlie perception and thinking.

Early results show that THC markedly diminishes power and coherence in the theta band, which sub-serves long-distance communication between neural assemblies. THC also appears to affect so-called event-related potentials (specifically the P300) in a manner which resembles endogenous psychoses.

You can read the full results of this very interesting study here: Opposite Effects of D-9-Tetrahydrocannabinol and Cannabidiol on Human Brain Function and Psychopathology

Using fMRI our co-worker Sagnik Bhattacharyya (IoP) found that THC and CBD produced opposite effects on neural activation relative to placebo in the cortex, amygdala, hippocampus and striatum. In a parallel experiment, we found that CBD inhibited THC-psychosis (and THC-induced tachycardia) in healthy subjects (Bhattacharyya et al. 2010). This has wider implications, given that most genetically-modified strains of modern cannabis have negligible CBD content, compared to traditional cannabis. It is also further evidence in support of CBD as a medicine in psychiatry.

Two new studies are planned. Firstly, we want to characterise the effects of CBD on electrical activity in the brain. Secondly, we are focussing on the therapeutic potential of CBD. Taking advantage of a virtual reality paradigm which immerses subjects in a 3-D interactive environment, we hypothesise that CBD will reduce anxiety, social phobia and paranoia in those vulnerable to such mental states. In the latter study, we are joined by Daniel Freeman (IoP), a leading authority on the psychology of paranoid thinking.

This Beckley research program will help understand how and why cannabis might contribute to states of psychosis, and also identify the role of the endocannabinoid system in determining these states. Such knowledge is vital in the search for a treatment to alleviate these states, as it identifies the neurotransmitter targets that any treatment should seek to manipulate.

At the same time, we will be contributing to the search for such treatments by investigating the efficacy of another component of cannabis, Cannabidiol (CBD), to relieve some of the distressing effects of THC. CBD has already been shown to have anti-psychotic properties so could be an important addition to the limited range of effective treatments for schizophrenia, one of the most debilitating and distressing diseases that mankind suffers from.