Hair concentrations of Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in cannabis consumers psychiatric patients (Preprint)

Background: Among young consumers of cannabis, a brief psychotic disorder (BPD) can be either the clinical manifestation of acute cannabis psychosis (ACP) or an announcement of schizophrenia’s onset. Clinicians are faced with the difficulty of making a differential diagnosis between disorders of the schizophrenic field and disorders induced by cannabis. To date, no clinical or even less paraclinical criteria have made it possible to differentiate syndromes whose prognoses and management are different.

Objective: We wanted to determine if these patients, cannabis users, suffering from BPD, present particular phenotypes of capillary cannabinoid concentrations (THC and CBD). In other words, it would be possible to make a first diagnosis just after the initial psychiatric evaluation, thus making it possible to overcome a significant delay (3–6 months), delaying the most appropriate care. Appropriate care and early therapeutic management are important if the pathology responsible for mental disorders is chronic psychosis.

Methods: Since 2010, we measured delta-9 tetrahydrocannabinol (THC) and cannabidiol (CBD) concentrations in head hair among New Caledonian patients, all cannabis consumers (n = 256). At the time of initial psychiatric consultation, a sample of 3 cm proximal length of head hair was prepared for analysis, and THC and CBD were then assayed by Gas Chromatography coupled with Mass Spectrometry (Limit Of Quantitation: 0.05 ng/mg). At the end of the 6 months medico-psychologic follow-up from the initial evaluation, four groups of cannabis users were identified according to the final psychiatric diagnosis: control, acute cannabis psychosis (ACP), chronic psychosis (CP), and other personality disorders (OPD) groups.

Results: In this study, a high hair level of THC detected (> 0.7 ng/mg) associated with a low hair CBD/THC ratio (< 0.26) are two parameters that taken together could be good markers of CP development. For OPD and ACP, hair CBD/THC ratios were higher in the ACP group (> 0.43) than in the OPD group (< 0.32).

Conclusions: This study highlights, once again, the protective role of CBD against the deleterious effects of THC. In association with clinical evaluation, this toxicological approach could be helpful for psychiatric diagnosis and would allow early management of BPD in cannabis consumers. For a consumer who does not present with a psychiatric disorder, it could give an information about the possibility of belonging to a group of patients at high risk of psychiatric decompensation. This provides an additional argument for efforts to control cannabis consumption by patients.