Randomised controlled trials (RCTs) of psilocybin have reported large antidepressant effects in adults with major depressive disorder and treatment-resistant depression (TRD). Given psilocybin's psychedelic effects, all published studies have included psychological support. These effects depend on serotonin 2A (5-HT2A) receptor activation, which can be blocked by 5-HT2A receptor antagonists like ketanserin or risperidone. In an animal model of depression, ketanserin followed by psilocybin had similar symptomatic effects as psilocybin alone.

To conduct a proof-of-concept RCT to (a) establish feasibility and tolerability of combining psilocybin and risperidone in adults with TRD, (b) show that this combination blocks the psychedelic effects of psilocybin and (c) provide pilot data on the antidepressant effect of this combination (compared with psilocybin alone).

In a 4-week, three-arm, ‘double dummy’ trial, 60 adults with TRD will be randomised to psilocybin 25 mg plus risperidone 1 mg, psilocybin 25 mg plus placebo, or placebo plus risperidone 1 mg. All participants will receive 12 h of manualised psychotherapy. Measures of feasibility will include recruitment and retention rates; tolerability and safety will be assessed by rates of drop-out attributed to adverse events and rates of serious adverse events. The 5-Dimensional Altered States of Consciousness Rating Scale will be a secondary outcome measure.

This trial will advance the understanding of psilocybin's mechanism of antidepressant action.

This line of research could increase acceptability and access to psilocybin as a novel treatment for TRD without the need for a psychedelic experience and continuous monitoring.

Background: Evidence suggests that cannabis use may be associated with suicidality in adolescence. Nevertheless, very few studies have assessed this association in low- and middle-income countries (LMICs). In this cross-sectional survey, we investigated the association of cannabis use and suicidal attempts in adolescents from 21 LMICs, adjusting for potential confounders.

Method: Data from the Global school-based Student Health Survey was analyzed in 86,254 adolescents from 21 countries [mean (SD) age = 13.7 (0.9) years; 49.0% girls]. Suicide attempts during past year and cannabis during past month and lifetime were assessed. Multivariable logistic regression analyses were conducted.

Results: The overall prevalence of past 30-day cannabis use was 2.8% and the age-sex adjusted prevalence varied from 0.5% (Laos) to 37.6% (Samoa), while the overall prevalence of lifetime cannabis use was 3.9% (range 0.5%–44.9%). The overall prevalence of suicide attempts during the past year was 10.5%. Following multivariable adjustment to potential confounding variables, past 30-day cannabis use was significantly associated with suicide attempts (OR = 2.03; 95% CI: 1.42–2.91). Lifetime cannabis use was also independently associated with suicide attempts (OR = 2.30; 95% CI: 1.74–3.04).

Conclusion: Our data indicate that cannabis use is associated with a greater likelihood for suicide attempts in adolescents living in LMICs. The causality of this association should be confirmed/refuted in prospective studies to further inform public health policies for suicide prevention in LMICs.

Depression and obesity are highly prevalent, and major impacts on public health frequently co-occur. Recently, we reported that having depression moderates the effect of the FTO gene, suggesting its implication in the association between depression and obesity.

To confirm these findings by investigating the FTO polymorphism rs9939609 in new cohorts, and subsequently in a meta-analysis.

The sample consists of 6902 individuals with depression and 6799 controls from three replication cohorts and two original discovery cohorts. Linear regression models were performed to test for association between rs9939609 and body mass index (BMI), and for the interaction between rs9939609 and depression status for an effect on BMI. Fixed and random effects meta-analyses were performed using METASOFT.

In the replication cohorts, we observed a significant interaction between FTO, BMI and depression with fixed effects meta-analysis (β=0.12, P = 2.7 × 10−4) and with the Han/Eskin random effects method (P = 1.4 × 10−7) but not with traditional random effects (β = 0.1, P = 0.35). When combined with the discovery cohorts, random effects meta-analysis also supports the interaction (β = 0.12, P = 0.027) being highly significant based on the Han/Eskin model (P = 6.9 × 10−8). On average, carriers of the risk allele who have depression have a 2.2% higher BMI for each risk allele, over and above the main effect of FTO.

This meta-analysis provides additional support for a significant interaction between FTO, depression and BMI, indicating that depression increases the effect of FTO on BMI. The findings provide a useful starting point in understanding the biological mechanism involved in the association between obesity and depression.