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The onset of frank psychosis is usually preceded by a prodromal phase characterized by attenuated psychotic symptoms. Currently, research on schizophrenia prodromal phase (ultra‐high risk for psychosis [UHR]) has focused on the risk of developing psychosis, on the transition to full blown psychosis and on its prediction. Neurobiological differences between UHR individuals who fully recover (remitters) versus those who show persistent/progressive prodromal symptoms (nonremitters) have been little explored. The endocannabinoid system constitutes a neuromodulatory system that plays a major role in brain development, synaptic plasticity, emotional behaviours and cognition. It comprises two cannabinoid receptors (CB1/CB2), two endocannabinoid ligands, arachidonylethanolamide (AEA) and 2‐arachidonoylglycerol (2AG) along with their inactivation enzymes. Despite much evidence that the endocannabinoid system is imbalanced during psychosis, very little is known about it in UHR. Therefore, we aimed to quantify the plasma endocannabinoid levels in UHR and healthy controls (HC) and verify if these metabolites could differentiate between remitters and nonremitters. Circulating concentrations of AEA (p =.003) and 2AG (p <.001) were lower in UHR when compared with HC, with no difference between remitters and nonremitters. Regarding clinical evolution, it was observed that out of 91 UHRs initially considered, 16 had psychiatric complaints (3 years of follow‐up). Considering those subjects, there were weak correlations between clinical parameters and plasma concentrations of endocannabinoids. Our results suggest that the endocannabinoids are imbalanced before frank psychosis and that changes can be seen in plasma of UHR individuals. These molecules proved to be potential biomarkers to identify individuals in the prodromal phase of psychosis. [ABSTRACT FROM AUTHOR]

Over the years CB2 cannabinoid receptors have received much less attention than CB1 receptors, the latter mediating most of the psychoactive effects of cannabis. Primarily this was due to difficulties in assigning a physiological function to CB2 receptors. In recent years this situation has changed, and CB2 receptors have been implicated in processes as diverse as analgesia, hepatic fibrosis, bone growth, and atherosclerosis. This special issue of the British Journal of Pharmacology addresses these and other topics in CB2 receptor research by compiling a series of reviews and primary research papers stemming from a meeting ‘CB22 cannabinoid receptors: New vistas’ that was held in Banff, Canada, from May 31 to June 3, 2007.British Journal of Pharmacology (2008) 153, 177–178; doi:10.1038/sj.bjp.0707617 [ABSTRACT FROM AUTHOR]