Plasmatic endocannabinoids are decreased in subjects with ultra-high risk of psychosis.

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.

Increased PLA2 activity in individuals at ultra-high risk for psychosis.

Phospholipase A2 is the main enzyme in the metabolism of membrane phospholipids. It comprises a family of enzymes divided into iPLA2, cPLA2 and sPLA2. Studies have reported increased PLA2 activity in psychotic patients, which suggests an accelerated breakdown of membrane phospholipids. In the present study we investigated whether increased PLA2 activity is also present in individuals at ultra-high risk (UHR) for psychosis. One-hundred fifty adults were included in this study (85 UHR and 65 controls). UHR was assessed using the "structured interview for prodromal syndromes". PLA2 activity was determined in platelets by a radio-enzymatic assay. We found in UHR individuals increased activities of iPLA2 (p < 0.001) and cPLA2 (p = 0.012) as compared to controls. No correlations were found between socio-demographic and clinical parameters and PLA2 activity. Our findings suggest that increased PLA2 activities may be useful as a biological risk-marker for psychotic disorders.

COX-2 pathway is upregulated in ultra-high risk individuals for psychosis.

BACKGROUND: The identification of Ultra-High Risk (UHR) individuals is thought to be useful for early intervention to improve psychosis outcomes. However, transition rates vary widely, and there is an effort to make these criteria more specific and accurate. Neuroinflammation has been discussed in the pathophysiology of psychosis. The metabolism of eicosanoids is a key process in inflammatory states. Therefore, we investigated whether the study of the inflammatory COX-2 pathway through the quantification of the eicosanoid levels can be a useful approach for the characterisation of UHR individuals. METHODS: One hundred and twenty-two individuals were included in this study (67 UHR and 55 controls) based on performance on the Prodromal Questionnaire. UHR status was assessed by Structured Interview for Prodromal Syndromes (SIPS). We determined the levels of Prostaglandin F2α (PGF2α), Prostaglandin E2 (PGE2), and Thromboxane B2 (TxB2) in plasma using ELISA assays. RESULTS: Concentrations of PGE2 and TxB2 were increased in UHR compared to controls (p = 0.01 and p < 0.05, respectively). PGE2 and PGF2α levels were correlated to negative symptoms (p < 0.01 and p < 0.05), whereas TxB2 correlated with positive symptoms (p = 0.05) as assessed by the SIPS. CONCLUSIONS: Our findings suggest that overactivation of the COX-2 pathway may be related to an increased risk for psychosis. However, our data do not allow us to draw conclusions related to the cause-effect mechanisms. Future studies should determine whether the levels of the eicosanoids have a predictive value for the transition of UHR to frank psychosis.