F. Markus Leweke

Cerebrospinal anandamide levels are elevated in acute schizophrenia and are inversely correlated with psychotic symptoms.

The endocannabinoids are a family of bioactive lipids that activate CB1 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=47) than healthy controls (n=84), dementia patients (n=13) or affective disorder patients (n=22). Such an alteration is absent in schizophrenics treated with ‘typical’ antipsychotics (n=37), which antagonize dopamine D2-like receptors, but not in those treated with ‘atypical’ antipsychotics (n=34), which preferentially antagonize 5HT2A receptors. Furthermore, we found that, in nonmedicated acute schizophrenics, CSF anandamide is negatively correlated with psychotic symptoms (rS=−0.452, P=0.001). The results suggest that anandamide elevation in acute paranoid schizophrenia may reflect a compensatory adaptation to the disease state.

Metabolic profiling of CSF: evidence that early intervention may impact on disease progression and outcome in schizophrenia.

Background The 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. Conclusions Our 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.

Antibodies to infectious agents in individuals with recent onset schizophrenia.

Abstract.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.

Cannabis and psychiatric disorders: it is not only addiction.

Since the discovery of the endocannabinoid system, a growing body of psychiatric research has emerged focusing on the role of this system in major psychiatric disorders like schizophrenia (SCZ), bipolar disorder (BD), major depression and anxiety disorder. Continuing in the line of earlier epidemiological studies, recent replication studies indicate that frequent cannabis use doubles the risk for psychotic symptoms and SCZ. Further points of clinical research interest are alterations of endocannabinoids and their relation to symptoms as well as postmortem analyses of cannabinoid CB1 receptor densities in SCZ. A possible neurobiological mechanism for the deleterious influence of cannabis use in SCZ has been suggested, involving the disruption of endogenous cannabinoid signaling and functioning. Even though the number of studies is still limited for affective and anxiety disorders, previous results suggest these diseases to be exciting objectives of cannabinoid‐associated research. Therefore, it became apparent that cannabis use is not only frequent in patients suffering from BD, but that it also induces manic symptoms in this group. In addition, prior antipsychotic treatment decreased the numerical density of CB1 immunoreactive glial cells in bipolar patients. Although the data on the influence of cannabis use on the development of major depression is controversial, cannabinoid compounds could display a new class of medication, as suggested by the antidepressive effects of the fatty acid amino hydrolase inhibitor URB597 in animal models. With numerous open questions and controversial results, further research is required to specify and extend the findings in this area, which provides a promising target for novel pharmacotherapeutic interventions.

Disease Biomarkers in Cerebrospinal Fluid of Patients with First-Onset Psychosis

Background Psychosis is a severe mental condition that is characterized by a loss of contact with reality and is typically associated with hallucinations and delusional beliefs. There are numerous psychiatric conditions that present with psychotic symptoms, most importantly schizophrenia, bipolar affective disorder, and some forms of severe depression referred to as psychotic depression. The pathological mechanisms resulting in psychotic symptoms are not understood, nor is it understood whether the various psychotic illnesses are the result of similar biochemical disturbances. The identification of biological markers (so-called biomarkers) of psychosis is a fundamental step towards a better understanding of the pathogenesis of psychosis and holds the potential for more objective testing methods. Methods and Findings Surface-enhanced laser desorption ionization mass spectrometry was employed to profile proteins and peptides in a total of 179 cerebrospinal fluid samples (58 schizophrenia patients, 16 patients with depression, five patients with obsessive-compulsive disorder, ten patients with Alzheimer disease, and 90 controls). Our results show a highly significant differential distribution of samples from healthy volunteers away from drug-naïve patients with first-onset paranoid schizophrenia. The key alterations were the up-regulation of a 40-amino acid VGF-derived peptide, the down-regulation of transthyretin at ~4 kDa, and a peptide cluster at ~6,800–7,300 Da (which is likely to be influenced by the doubly charged ions of the transthyretin protein cluster). These schizophrenia-specific protein/peptide changes were replicated in an independent sample set. Both experiments achieved a specificity of 95% and a sensitivity of 80% or 88% in the initial study and in a subsequent validation study, respectively. Conclusions Our results suggest that the application of modern proteomics techniques, particularly mass spectrometric approaches, holds the potential to advance the understanding of the biochemical basis of psychiatric disorders and may in turn allow for the development of diagnostics and improved therapeutics. Further studies are required to validate the clinical effectiveness and disease specificity of the identified biomarkers.

Acute and chronic cannabinoid treatment differentially affects recognition memory and social behavior in pubertal and adult rats.

Although cannabis belongs to the most widely used drugs among adolescents, little is known about its acute and lasting neurobehavioral effects during critical developmental periods. In the present study we investigated acute and long‐term behavioral effects of the cannabinoid agonist WIN 55,212‐2 (WIN) in pubertal and adult rats. Chronic WIN (1.2 mg/kg)/vehicle treatment was extended over 25 days throughout puberty, from postnatal day (pd) 40 to pd 65, or for a similar time period in adult rats (> pd 80). All animals were tested at three time points for object/social recognition memory, social interaction and spontaneous social behavior. First, acute cannabinoid effects were investigated directly after the first injection. Additionally, behavioral performance was retested 24 hours and 15 days after cessation of WIN treatment. Chronic pubertal WIN treatment induced persistent object/social recognition deficits, indicating a general impairment in short‐term information processing. Lasting disturbances in social behavior, social play and self‐grooming were also found. Furthermore, behavioral deficits seen after acute WIN administration were more pronounced in pubertal than in adult rats. These results confirm our recent findings that chronic pubertal cannabinoid treatment leads to lasting behavioral alterations in adulthood, and they show that acute cannabinoid administration induces more severe behavioral deficits in pubertal rats than in mature animals. We therefore conclude that an immature brain is more susceptible to the acute and chronic effects of exogenous cannabinoids than an adult organism, which might be explained by an overactive endocannabinoid system and concomittant maturational disturbances in further neurotransmitter systems during pubertal development.

Validation of a Blood-Based Laboratory Test to Aid in the Confirmation of a Diagnosis of Schizophrenia

We describe the validation of a serum-based test developed by Rules-Based Medicine which can be used to help confirm the diagnosis of schizophrenia. In preliminary studies using multiplex immunoassay profiling technology, we identified a disease signature comprised of 51 analytes which could distinguish schizophrenia (n = 250) from control (n = 230) subjects. In the next stage, these analytes were developed as a refined 51-plex immunoassay panel for validation using a large independent cohort of schizophrenia (n = 577) and control (n = 229) subjects. The resulting test yielded an overall sensitivity of 83% and specificity of 83% with a receiver operating characteristic area under the curve (ROC-AUC) of 89%. These 51 immunoassays and the associated decision rule delivered a sensitive and specific prediction for the presence of schizophrenia in patients compared to matched healthy controls.

Anandamide elevation in cerebrospinal fluid in initial prodromal states of psychosis

Anandamide is a bioactive lipid binding to cannabinoid receptors. A homeostatic role for anandamide has been suggested in schizophrenia. We investigated its role in initial prodromal states of psychosis. We measured the levels of anandamide and its structural analog oleoylethanolamide in cerebrospinal fluid and serum of patients in the initial prodromal state (n=27) alongside healthy volunteers (n=81) using high-performance liquid chromatograph/mass spectrometry. Cerebrospinal anandamide levels in patients were significantly elevated. Patients with lower levels showed a higher risk for transiting to psychosis earlier. This anandamidergic up-regulation in the initial prodromal course may suggest a protective role of the endocannabinoid system in early schizophrenia.

Altered levels of circulating insulin and other neuroendocrine hormones associated with the onset of schizophrenia

Recently, we showed that the circulating levels of insulin-related peptides and the secretory granule protein chromogranin A were increased in small cohorts of first onset schizophrenia patients. Assuming that this effect was associated with impaired insulin signalling, we investigated the possibility that secretion of other hormones is also affected in schizophrenia. Multiplex immunoassay analysis of 21 hormones and hormone-related molecules was carried out using sera from 236 first and recent onset schizophrenia patients and 230 matched controls. Serum concentrations of insulin and chromogranin A were increased in schizophrenia subjects, consistent with our previous study. In addition, we found elevated concentrations of pancreatic polypeptide, prolactin, progesterone and cortisol, and decreased levels of growth hormone. We also found that growth hormone levels were decreased in post-mortem pituitaries obtained from chronic schizophrenia patients. It will be important to determine whether any of these molecules are involved in the pathosphysiology of schizophrenia or if they reflect the associated insulin resistance. We conclude that function of multiple components of the hypothalamic-pituitary-adrenal-gonadal axis may be affected in schizophrenia. This could have important implications for future biomarker discovery efforts and personalized medicine strategies based on patient stratification for the treatment of this debilitating disorder.

Gastrointestinal inflammation and associated immune activation in schizophrenia

Immune factors are implicated in normal brain development and in brain disorder pathogenesis. Pathogen infection and food antigen penetration across gastrointestinal barriers are means by which environmental factors might affect immune-related neurodevelopment. Here, we test if gastrointestinal inflammation is associated with schizophrenia and therefore, might contribute to bloodstream entry of potentially neurotropic milk and gluten exorphins and/or immune activation by food antigens. IgG antibodies to Saccharomyces cerevisiae (ASCA, a marker of intestinal inflammation), bovine milk casein, wheat-derived gluten, and 6 infectious agents were assayed. Cohort 1 included 193 with non-recent onset schizophrenia, 67 with recent onset schizophrenia and 207 non-psychiatric controls. Cohort 2 included 103 with first episode schizophrenia, 40 of whom were antipsychotic-naïve. ASCA markers were significantly elevated and correlated with food antigen antibodies in recent onset and non-recent onset schizophrenia compared to controls (p≤0.00001-0.004) and in unmedicated individuals with first episode schizophrenia compared to those receiving antipsychotics (p≤0.05-0.01). Elevated ASCA levels were especially evident in non-recent onset females (p≤0.009), recent onset males (p≤0.01) and in antipsychotic-naïve males (p≤0.03). Anti-food antigen antibodies were correlated to antibodies against Toxoplasma gondii, an intestinally-infectious pathogen, particularly in males with recent onset schizophrenia (p≤0.002). In conclusion, gastrointestinal inflammation is a relevant pathology in schizophrenia, appears to occur in the absence of but may be modified by antipsychotics, and may link food antigen sensitivity and microbial infection as sources of immune activation in mental illness.