Cannabidiol is a component of marijuana that does not activate cannabinoid receptors, but moderately inhibits the degradation of the endocannabinoid anandamide. We previously reported that an elevation of anandamide levels in cerebrospinal fluid inversely correlated to psychotic symptoms. Furthermore, enhanced anandamide signaling let to a lower transition rate from initial prodromal states into frank psychosis as well as postponed transition. In our translational approach, we performed a double-blind, randomized clinical trial of cannabidiol vs amisulpride, a potent antipsychotic, in acute schizophrenia to evaluate the clinical relevance of our initial findings. Either treatment was safe and led to significant clinical improvement, but cannabidiol displayed a markedly superior side-effect profile. Moreover, cannabidiol treatment was accompanied by a significant increase in serum anandamide levels, which was significantly associated with clinical improvement. The results suggest that inhibition of anandamide deactivation may contribute to the antipsychotic effects of cannabidiol potentially representing a completely new mechanism in the treatment of schizophrenia.

The endocannabinoids are a family of bioactive lipids that activate CB 1 cannabinoid receptors in the brain and exert intense emotional and cognitive effects. Here, we have examined the role of endocannabinoid signaling in psychotic states by measuring levels of the endocannabinoid anandamide in cerebrospinal fluid (CSF) of acute paranoid-type schizophrenic patients. We found that CSF anandamide levels are eight-fold higher in antipsychotic-naïve first-episode paranoid schizophrenics (n ¼ 47) than healthy controls (n ¼ 84), dementia patients (n ¼ 13) or affective disorder patients (n ¼ 22). Such an alteration is absent in schizophrenics treated with 'typical' antipsychotics (n ¼ 37), which antagonize dopamine D 2 -like receptors, but not in those treated with 'atypical' antipsychotics (n ¼ 34), which preferentially antagonize 5HT 2A receptors. Furthermore, we found that, in nonmedicated acute schizophrenics, CSF anandamide is negatively correlated with psychotic symptoms (r S ¼ À0.452, P ¼ 0.001). The results suggest that anandamide elevation in acute paranoid schizophrenia may reflect a compensatory adaptation to the disease state.

Background: Previous studies have shown that cerebrospinal fluid (CSF) from schizophrenic patients contains significantly higher levels of the endogenous cannabinoid anandamide than does CSF from healthy volunteers. Moreover, CSF anandamide levels correlated inversely with psychotic symptoms, suggesting that anandamide release in the central nervous system (CNS) may serve as an adaptive mechanism countering neurotransmitter abnormalities in acute psychoses. In the present study we examined whether cannabis use may alter such a mechanism. Methods: We used liquid chromatography/mass spectrometry (LC/MS) to measure anandamide levels in serum and CSF from firstepisode, antipsychotic-naïve schizophrenics (n = 47) and healthy volunteers (n = 81). Based on reported patterns of cannabis use and urine Δ 9 -tetrahydrocannabinol (Δ 9 -THC) tests, each subject group was further divided into two subgroups: 'low-frequency' and 'high-frequency' cannabis users (lifetime use ≤5 times and N20 times, respectively). Serum Δ 9 -THC was investigated to determine acute use and three patients were excluded from the analysis due to detectable Δ 9 -THC levels in serum. Results: Schizophrenic low-frequency cannabis users (n = 25) exhibited N 10-fold higher CSF anandamide levels than did schizophrenic high-frequency users (n = 19, p = 0.008), healthy low-frequency (n = 55, p b 0.001) or high-frequency users (n = 26, p b 0.001). In contrast, no significant differences in serum anandamide levels were found among the four subgroups. CSF anandamide levels and disease symptoms were negatively correlated in both user groups. Conclusions:The results indicate that frequent cannabis exposure may down-regulate anandamide signaling in the CNS of schizophrenic patients, but not of healthy individuals. Thus, our findings suggest that alterations in endocannabinoid signaling might be an important component of the mechanism through which cannabis impacts mental health.

BackgroundThe identification of schizophrenia biomarkers is a crucial step towards improving current diagnosis, developing new presymptomatic treatments, identifying high-risk individuals and disease subgroups, and assessing the efficacy of preventative interventions at a rate that is not currently possible.Methods and Findings 1H nuclear magnetic resonance spectroscopy in conjunction with computerized pattern recognition analysis were employed to investigate metabolic profiles of a total of 152 cerebrospinal fluid (CSF) samples from drug-naïve or minimally treated patients with first-onset paranoid schizophrenia (referred to as “schizophrenia” in the following text) and healthy controls. Partial least square discriminant analysis showed a highly significant separation of patients with first-onset schizophrenia away from healthy controls. Short-term treatment with antipsychotic medication resulted in a normalization of the disease signature in over half the patients, well before overt clinical improvement. No normalization was observed in patients in which treatment had not been initiated at first presentation, providing the first molecular evidence for the importance of early intervention for psychotic disorders. Furthermore, the alterations identified in drug-naïve patients could be validated in a test sample set achieving a sensitivity and specificity of 82% and 85%, respectively.ConclusionsOur findings suggest brain-specific alterations in glucoregulatory processes in the CSF of drug-naïve patients with first-onset schizophrenia, implying that these abnormalities are intrinsic to the disease, rather than a side effect of antipsychotic medication. Short-term treatment with atypical antipsychotic medication resulted in a normalization of the CSF disease signature in half the patients well before a clinical improvement would be expected. Furthermore, our results suggest that the initiation of antipsychotic treatment during a first psychotic episode may influence treatment response and/or outcome.

We investigated the levels of antibodies to infectious agents in the serum and cerebral spinal fluids (CSFs) of individuals with recent onset schizophrenia and compared these levels to those of controls without psychiatric disease. We found that untreated individuals with recent onset schizophrenia had significantly increased levels of serum and CSF IgG antibody to cytomegalovirus and Toxoplasma gondii as compared to controls. The levels of serum IgM class antibodies to these agents were not increased. Untreated individuals with recent onset schizophrenia also had significantly lower levels of serum antibody to human herpesvirus type 6 and varicella zoster virus as compared to controls. Levels of antibodies to herpes simplex virus type 1, herpes simplex virus type 2, and Epstein Barr virus, and did not differ from cases and controls. We also found that treatment status had a major effect on the levels of antibodies in this population. Individuals who were receiving treatment had lower levels of antibodies to cytomegalovirus and Toxoplasma gondii, and higher levels of serum antibodies to human herpesvirus type 6 as compared to untreated individuals. The level of antibodies to Toxoplasma and human herpesvirus type 6 measured in treated individuals did not differ from the levels measured in controls. In the case of cytomegalovirus, the levels of CSF antibodies in treated individuals did not differ from those of controls, while the level of serum IgG antibodies to CMV remained slightly greater than controls in this population. Our studies indicate that untreated individuals with recent onset schizophrenia have altered levels of antibodies to cytomegalovirus, Toxoplasma gondii, and human herpesvirus type 6 while the levels of these antibodies in treated individuals with recent onset schizophrenia are similar to those of controls. These findings indicate that infectious agents may play a role in the etiopathogenesis of some cases of schizophrenia.