Psychotic patients who used cannabis frequently before illness onset have higher genetic predisposition to schizophrenia than those who did not

The Effects of Cannabidiol and δ-9-Tetrahydrocannabinol in Social Cognition: A Naturalistic Controlled Study

Background: Social cognition abilities such as empathy and the Theory of Mind (ToM) have been shown to be impaired in neuropsychiatric conditions such as psychotic, autistic, and bipolar disorders. The endocannabinoid system (ECS) seems to play a role in social behavior and emotional processing while it also seems to play a role in those neuropsychiatric conditions showing social cognition impairments. Main plant cannabinoids delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) modulate the ECS and, due to their opposite effects, have been proposed as both cause and treatment for neuropsychiatric-related disorders such as schizophrenia, anxiety, or post-traumatic stress disorder (PTSD). The aim of this study was to test the effects of THC and CBD on social cognition abilities in chronic cannabis users. Method: Eighteen members from a cannabis social club were tested for social cognition effects under the effects of different full spectrum cannabis extracts containing either THC, CBD, THC+CBD, or placebo in a naturalistic randomized double-blind crossover placebo-controlled study. Results: Results showed that participants under the effects of THC showed lower cognitive empathy when compared with the effects of CBD but not when those were compared with THC+CBD or placebo. Also, participants showed higher cognitive ToM under the effects of CBD when compared with the effects of placebo, but not when those were compared with THC or THC+CBD. However, we did not find differences on the emotional scales for empathy or ToM. Conclusions: This study provides evidence for the interaction between the effects of THC and CBD and social cognition abilities in a naturalistic environment, which can be of special interest for the clinical practice of medical cannabis on neuropsychiatric disorders. We show for the first time that CBD can improve ToM abilities in chronic cannabis users. Our results might help to understand the role of the ECS in social cognition, and their association with psychiatric and neurodevelopmental disorders such as schizophrenia or autism. Finally, we demonstrate how reliable methodologies can be implemented in naturalistic environments to collect valid ecological evidence outside classic laboratory settings.

Characterization of childhood trauma, hippocampal mediation and Cannabis use in a large dataset of psychosis and non-psychosis individuals

BACKGROUND

Cannabis use (CA) and childhood trauma (CT) independently increase the risk of earlier psychosis onset; but their interaction in relation to psychosis risk and association with endocannabinoid-receptor rich brain regions, i.e. the hippocampus (HP), remains unclear. The objective was to determine whether lower age of psychosis onset (AgePsyOnset) is associated with CA and CT through mediation by the HP volumes, and genetic risk, as measured by schizophrenia polygene scores (SZ-PGRS).

METHODS

Cross-sectional, case-control, multicenter sample from 5 metropolitan US regions. Participants (n = 1185) included 397 controls not affected by psychosis (HC); 209 participants with bipolar disorder type-1; 279 with schizoaffective disorder; and 300 with schizophrenia (DSM IV-TR). CT was assessed using the Childhood Trauma Questionnaire (CTQ); CA was assessed by self-reports and trained clinical interviewers. Assessment included neuroimaging, symptomatology, cognition and calculation of the SZ polygenic risk score (SZ-PGRS).

RESULTS

In survival analysis, CT and CA exposure interact to be associated with lower AgePsyOnset. At high CT or CA, CT or CA are individually sufficient to affect AgePsyOnset. CT relation with AgePsyOnset is mediated in part by the HP in CA users before AgePsyOnset. CA before AgePsyOnset is associated with higher SZ-PGRS and correlated with younger age at CA usage.

DISCUSSION

CA and CT interact to increase risk when moderate; while severe CT and/or CA abuse/dependence are each sufficient to affect AgePsyOnset, indicating a ceiling effect. Probands with/out CA before AgePsyOnset differ on biological variables, suggesting divergent pathways to psychosis.

FUNDING

MH077945; MH096942; MH096913; MH077862; MH103368; MH096900; MH122759.

Lost in Translation: Challenges in the Diagnosis and Treatment of Early-Onset Schizophrenia

Early-onset schizophrenia (EOS) is a heterogeneous condition that has a serious, insidious clinical course and poor long-term mental health outcomes. The clinical presentations are highly complex due to the overlapping symptomatology with other illnesses, which contributes to a delay in the diagnosis. The objective of the review is to study if an earlier age of onset (AAO) of EOS has poor clinical outcomes, the diagnostic challenges of EOS, and effective treatment strategies. The review provides a comprehensive literature search of 5966 articles and summarizes 126 selected for empirical evidence to methodically consider challenges in diagnosing and treating EOS for practicing clinicians. The risk factors of EOS are unique but have been shared with many other neuropsychiatric illnesses. Most of the risk factors, including genetics and obstetric complications, are nonmodifiable. The role of early diagnosis in reducing the duration of untreated psychosis (DUP) remains critical to reducing overall morbidity. Many specific issues contribute to the risk and clinical outcomes. Therefore, issues around diagnostic ambiguity, treatment resistance, nonadherence, and rehospitalizations further extend the DUP. There is hesitancy to initiate clozapine early, even though the empirical evidence strongly supports its use. There is a growing body of research that suggests the use of long-acting injectables to address nonadherence, and these measures are largely underutilized in acute settings. The clinical presentations of EOS are complex. In addition to the presence of specific risk factors, patients with an early onset of illness are also at a higher risk for treatment resistance. While there is a need to develop tools for early diagnosis, established evidence-based measures to address nonadherence, psychoeducation, and resistance must be incorporated into the treatment planning.

Profiles and factors associated with schizophrenia in eastern Ethiopia: A matched case-control study

Background

Despite its strong hereditary and genetic connections, there are other factors reported to be linked to schizophrenia, but not well studied in eastern Ethiopia.

Objective

This study was aimed to investigating the potential profiles and factors associated with schizophrenia in eastern Ethiopia.

Materials and methods

A matched case-control study was conducted in two public hospitals from December 1, 2021, to January 30, 2022. Cases were patients with schizophrenia who visited the hospitals, and controls were healthy individuals without any mental illness who visited the same hospitals. A questionnaire was used to collect the data. Cases and controls were matched using age and sex. STATA-14 was used for analysis. A conditional logistic regression with an adjusted odds ratio (AOR) and a 95% confidence interval (CI) was applied to identify the determinants. P-values of <0.05 were used to build the final model as a measure of statistical significance.

Results

The mean age of the study participants group was 28.6 (±8.44) years, mean age for cases was 28.7(±8.5) ranging from 18 to 56 years and the mean age for the controls was 28.4 (±8.5), ranging from 18 to 60 years. About 181 (83.03%) of the participants were male. The odds of having schizophrenia was about 12.2 times higher among participants with family history of mental illness (AOR: 12.21; 95% CI: 4.83-30.00). The odds of having schizophrenia was 4.5 times higher among polysubstance users (AOR: 4.45; 95% CI: 1.28-5.45) and 2.8 times higher among khat consumers (AOR: 2.82; 95% CI: 1.23-6.45) compared to their counterparts.

Conclusion

Our findings show that genetic risk factors as well as some modifiable behaviors are associated to schizophrenia in eastern Ethiopia. At all levels, special attention should be given to those who are at risk.

Is there an association between inflammatory/anti-oxidant markers and the presence of psychotic symptoms or severity of illness in mood and psychotic disorders? A multi-centric study on a drug-free sample

The immune and antioxidant systems are intimately connected and their role in the etiology of major psychiatric disorders is currently under study. The aim of this study was to evaluate the potential associations between inflammatory/antioxidant peripheral markers and presence of psychotic symptoms or severity of illness in patients affected by major psychiatric disorders.

One hundred and twenty-six drug-free patients were included. A blood sample was collected to measure total/B/T lymphocytes and plasma levels of albumin, total bilirubin, uric acid, C-reactive protein, and vitamins A and E. Severity of illness was assessed using psychometric scales. Groups of patients divided according to diagnosis were compared in terms of measured markers using multivariate analyses of variance (MANOVAs). Linear and logistic regression analyses were performed to investigate the potential association between markers and severity of illness or presence/absence of psychotic symptoms.

Albumin plasma levels were higher in patients with substance-induced psychotic disorder (SIPD) than subjects affected by schizophrenia (F ​= ​4.923; p ​= ​0.003). Lower vitamin E (OR ​= ​0.81; p ​= ​0.014) and T lymphocyte (OR ​= ​0.99; p ​= ​0.048) plasma levels were predictive of lifetime psychotic symptoms. Lower vitamin A levels were associated with higher Montgomery-Åsberg Depression Rating Scale scores (β ​= ​-24.26; p ​= ​0.029), independent of diagnosis.

Patients with SIPD may be less vulnerable to oxidative stress. The severity of depressive symptoms, inversely associated with vitamin A plasma levels, is likely to be modulated by the degree of inflammation. Patients presenting with lifetime psychotic symptoms may be more vulnerable to oxidative stress and may have a higher activation of humoral immunity.

Premorbid characteristics of patients with DSM-IV psychotic disorders

INTRODUCTION

Psychotic disorder not otherwise specified (PNOS) is considered part of the psychosis spectrum, together with schizophrenia spectrum disorders (SSD) and psychotic bipolar spectrum disorders (PBD). The atypical clinical presentations of PNOS conditions may lead to uncertainty regarding treatment choices and expected outcomes. PNOS is understudied, and little is known about patients' premorbid characteristics including premorbid adjustment, prevalence of early cannabis use and childhood trauma. Knowledge about early illness phases can increase our understanding of this diagnostic group.

METHODS

We included 1099 participants from the Norwegian TOP-study; 688 with narrow SSD diagnoses (schizophrenia, schizoaffective disorder, schizophreniform disorder), 274 with PBD (psychotic bipolar 1 and bipolar NOS) and 137 with PNOS diagnosed with the SCID-I for DSM-IV. Participants were assessed with the Premorbid Adjustment Scale (PAS) divided into the areas of premorbid academic and social functioning. We obtained information on age at first exposure to cannabis and use of cannabis before the age of 16. The participants also provided information regarding early traumatic experiences using the Childhood Trauma Questionnaire (CTQ).

RESULTS

Participants with PNOS and SSD had poorer premorbid academic functioning than those with PBD (F_{2, 1029} = 7.81, p < 0.001, _pη² = 0.015). Premorbid social adjustment was significantly worse in the SSD group compared to the PBD group (F_{2, 1024} = 3.10, p = 0.045, _pη² = 0.006), with PNOS in the middle position. Significantly more of the participants with PNOS (17.5%) and SSD (11.5%) used cannabis before the age of 16 compared with PBD (5.3%, Wald χ² = 6.86, p = 0.03). There were no significant differences between the three groups regarding mean CTQ scores or in the proportion of participants who had experienced at least one type of childhood adversity.

CONCLUSIONS

Participants with PNOS appear as more similar to participants with SSD than to those with PBD regarding early premorbid adjustment and early cannabis use. The results indicate that many conditions classified as PNOS have functional impairments and problematic substance use from an early age. The prevalence of childhood adversities are high in all three groups.

A comprehensive gene-centric pleiotropic association analysis for 14 psychiatric disorders with GWAS summary statistics

BACKGROUND

Recent genome-wide association studies (GWASs) have revealed the polygenic nature of psychiatric disorders and discovered a few of single-nucleotide polymorphisms (SNPs) associated with multiple psychiatric disorders. However, the extent and pattern of pleiotropy among distinct psychiatric disorders remain not completely clear.

METHODS

We analyzed 14 psychiatric disorders using summary statistics available from the largest GWASs by far. We first applied the cross-trait linkage disequilibrium score regression (LDSC) to estimate genetic correlation between disorders. Then, we performed a gene-based pleiotropy analysis by first aggregating a set of SNP-level associations into a single gene-level association signal using MAGMA. From a methodological perspective, we viewed the identification of pleiotropic associations across the entire genome as a high-dimensional problem of composite null hypothesis testing and utilized a novel method called PLACO for pleiotropy mapping. We ultimately implemented functional analysis for identified pleiotropic genes and used Mendelian randomization for detecting causal association between these disorders.

RESULTS

We confirmed extensive genetic correlation among psychiatric disorders, based on which these disorders can be grouped into three diverse categories. We detected a large number of pleiotropic genes including 5884 associations and 2424 unique genes and found that differentially expressed pleiotropic genes were significantly enriched in pancreas, liver, heart, and brain, and that the biological process of these genes was remarkably enriched in regulating neurodevelopment, neurogenesis, and neuron differentiation, offering substantial evidence supporting the validity of identified pleiotropic loci. We further demonstrated that among all the identified pleiotropic genes there were 342 unique ones linked with 6353 drugs with drug-gene interaction which can be classified into distinct types including inhibitor, agonist, blocker, antagonist, and modulator. We also revealed causal associations among psychiatric disorders, indicating that genetic overlap and causality commonly drove the observed co-existence of these disorders.

CONCLUSIONS

Our study is among the first large-scale effort to characterize gene-level pleiotropy among a greatly expanded set of psychiatric disorders and provides important insight into shared genetic etiology underlying these disorders. The findings would inform psychiatric nosology, identify potential neurobiological mechanisms predisposing to specific clinical presentations, and pave the way to effective drug targets for clinical treatment.

Eye movements in patients in early psychosis with and without a history of cannabis use

It is unclear whether early psychosis in the context of cannabis use is different from psychosis without cannabis. We investigated this issue by examining whether abnormalities in oculomotor control differ between patients with psychosis with and without a history of cannabis use. We studied four groups: patients in the early phase of psychosis with a history of cannabis use (EPC; n = 28); patients in the early phase of psychosis without (EPNC; n = 25); controls with a history of cannabis use (HCC; n = 16); and controls without (HCNC; n = 22). We studied smooth pursuit eye movements using a stimulus with sinusoidal waveform at three target frequencies (0.2, 0.4 and 0.6 Hz). Participants also performed 40 antisaccade trials. There were no differences between the EPC and EPNC groups in diagnosis, symptom severity or level of functioning. We found evidence for a cannabis effect (χ2 = 23.14, p < 0.001), patient effect (χ2 = 4.84, p = 0.028) and patient × cannabis effect (χ2 = 4.20, p = 0.04) for smooth pursuit velocity gain. There was a large difference between EPC and EPNC (g = 0.76-0.86) with impairment in the non cannabis using group. We found no significant effect for antisaccade error whereas patients had fewer valid trials compared to controls. These data indicate that impairment of smooth pursuit in psychosis is more severe in patients without a history of cannabis use. This is consistent with the notion that the severity of neurobiological alterations in psychosis is lower in patients whose illness developed in the context of cannabis use.

The Cannabinoid CB1 Receptor in Schizophrenia

Converging lines of evidence from epidemiological, preclinical, and experimental studies indicate that the endocannabinoid system may be involved in the pathophysiology of schizophrenia and suggest that the cannabinoid CB₁ receptor may be a potential therapeutic target. In view of this, we first provide an overview of the endocannabinoid system and systematically review the evidence for CB₁ receptor alterations in animal models of schizophrenia and clinical studies in schizophrenia. MEDLINE, EMBASE, PsycArticles, and PsycINFO were systematically searched from inception until January 7, 2020. Of 1187 articles, 24 were included in the systematic review, including 8 preclinical studies measuring the CB₁ receptor in the context of an established animal model of schizophrenia and 16 clinical studies investigating the CB₁ receptor in schizophrenia. The majority of preclinical studies (6 of 8) have shown that the CB₁ receptor is reduced in the context of animal models of schizophrenia. Moreover, the majority of in vivo clinical imaging studies that used arterial blood sampling to quantify the radiotracer kinetics (3 of 4) have shown reduced CB₁ receptor availability in schizophrenia. However, mixed findings have been reported in ex vivo literature, including reports of no change in receptor levels (5 of 11), increased receptor levels (4 of 11), and decreased receptor levels (2 of 11). We review methodological reasons for these discrepancies and review how CB₁ receptor dysfunction may contribute to the pathophysiology of schizophrenia, drawing on the role of the receptor in regulating synaptic transmission and synaptic plasticity. We also discuss how the CB₁ receptor may be a potential therapeutic target.

Translating big data to better treatment in bipolar disorder - a manifesto for coordinated action

Bipolar disorder (BD) is a major healthcare and socio-economic challenge. Despite its substantial burden on society, the research activity in BD is much smaller than its economic impact appears to demand. There is a consensus that the accurate identification of the underlying pathophysiology for BD is fundamental to realize major health benefits through better treatment and preventive regimens. However, to achieve these goals requires coordinated action and innovative approaches to boost the discovery of the neurobiological underpinnings of BD, and rapid translation of research findings into development and testing of better and more specific treatments. To this end, we here propose that only a large-scale coordinated action can be successful in integrating international big-data approaches with real-world clinical interventions. This could be achieved through the creation of a Global Bipolar Disorder Foundation, which could bring government, industry and philanthropy together in common cause. A global initiative for BD research would come at a highly opportune time given the seminal advances promised for our understanding of the genetic and brain basis of the disease and the obvious areas of unmet clinical need. Such an endeavour would embrace the principles of open science and see the strong involvement of user groups and integration of dissemination and public involvement with the research programs. We believe the time is right for a step change in our approach to understanding, treating and even preventing BD effectively.

Effects of haloperidol on the delta-9-tetrahydrocannabinol response in humans: a responder analysis

RATIONALE

Δ-9-Tetrahydrocannabinol (Δ-9-THC) produces psychotomimetic effects in humans. However, the role of dopamine signaling in producing such effects is unclear. We hypothesized that dopaminergic antagonism would reduce the psychotomimetic effect of Δ-9-THC.

OBJECTIVE

The objective of this study was to evaluate whether pre-treatment with haloperidol would alter the psychotomimetic and perceptual-altering effects of Δ-9-THC, measured by the Positive and Negative Syndrome Scale for Schizophrenia (PANSS) and the Clinician-Administered Dissociative Symptom Scale (CADSS) in humans.

METHODS

In a two-test-day double-blind study, 28 healthy individuals were administered with active (0.057 mg/kg) or placebo oral haloperidol, followed 90 and 215 min later by intravenous administration of active (0.0286 mg/kg) Δ-9-THC and placebo, respectively. This secondary analysis was conducted because of the observation in other studies and in our data that a significant proportion of individuals may not have an adequate response to THC (floor effect), thus limiting the ability to test an interaction. Therefore, this analysis was performed including only responders to THC (n = 10), defined as individuals who had an increase of at least one point on the PANSS positive scale, consistent with prior human laboratory studies.

RESULTS

In the 10 responders, Δ-9-THC-induced increases in PANSS positive scores were significantly lower in the haloperidol condition (1.1 + 0.35) compared with the placebo condition (2.9 + 0.92).

CONCLUSION

This responder analysis showed that haloperidol did reduce the psychotomimetic effect of Δ-9-THC, supporting the hypothesis that dopaminergic signaling may participate in the psychosis-like effects of cannabinoids.

Exposure to cannabinoids can lead to persistent cognitive and psychiatric disorders

BACKGROUND

Cannabinoids are proposed in a wide array of medical indications. Yet, the evaluation of adverse effects in controlled clinical studies, following the evidence-based model, has partly been bypassed. On the other hand, studies on the consequences of recreational use of cannabis and experimental studies bring some insights on the potential long-term consequences of cannabinoids use.

RESULTS

Epidemiological studies have consistently demonstrated that cannabis use is associated with a risk of persistent cognitive deficits and increased risk of schizophrenia-like psychoses. These risks are modulated by the dose and duration of use, on top of age of use and genetic factors, including partially shared genetic predisposition with schizophrenia. Experimental studies in healthy humans showed that cannabis and its principal psychoactive component, the delta-9-tetrahydrocannabinol (THC), could produce transient, dose-dependent, psychotic symptoms as well as cognitive effects, which can be attenuated by cannabidiol (CBD). Studies in rodents have confirmed these effects and shown that adolescent exposure results in structural changes and impaired synaptic plasticity, impacting fronto-limbic systems that are critically involved in higher brain functions. The endocannabinoid system plays an important role in brain maturation. Its over-activation by cannabinoid receptor type 1 agonists (e.g., THC) during adolescence and the resulting changes in neuroplasticity could alter brain maturation and cause long-lasting changes that persist in the adult brain.

CONCLUSIONS

Exposure to cannabinoids can have long-term impact on the brain, with an inter-individual variability that could be conveyed by personal and family history of psychiatric disorders and genetic background. Adolescence and early adulthood are critical periods of vulnerability.

SIGNIFICANCE

The assessment of benefice-risk balance of medical use of cannabis and cannabinoids needs to carefully explore populations that could be more at-risk of psychiatric and cognitive complications.

Polygenic Risk Scores in Clinical Psychology: Bridging Genomic Risk to Individual Differences

Genomewide association studies (GWASs) across psychiatric phenotypes have shown that common genetic variants generally confer risk with small effect sizes (odds ratio < 1.1) that additively contribute to polygenic risk. Summary statistics derived from large discovery GWASs can be used to generate polygenic risk scores (PRS) in independent, target data sets to examine correlates of polygenic disorder liability (e.g., does genetic liability to schizophrenia predict cognition?). The intuitive appeal and generalizability of PRS have led to their widespread use and new insights into mechanisms of polygenic liability. However, when currently applied across traits they account for small amounts of variance (<3%), are relatively uninformative for clinical treatment, and, in isolation, provide no insight into molecular mechanisms. Larger GWASs are needed to increase the precision of PRS, and novel approaches integrating various data sources (e.g., multitrait analysis of GWASs) may improve the utility of current PRS.