Placebo and nocebo effects are widely reported across psychiatric conditions, yet have seldom been examined in the context of gambling disorder. Through meta-analysis, we examined placebo effects, their moderating factors, and nocebo effects, from available randomised, controlled pharmacological clinical trials in gambling disorder.

We searched, up to 19 February 2024, a broad range of databases, for double-blind randomised controlled trials (RCTs) of medications for gambling disorder. Outcomes were gambling symptom severity and quality of life (for efficacy), and drop outs due to medication side effects in the placebo arms.

We included 16 RCTs (n = 833) in the meta-analysis. The overall effect size for gambling severity reduction in the placebo arms was 1.18 (95%CI 0.91–1.46) and for quality of life improvement was 0.63 (0.42-0.83). Medication class, study sponsorship, trial duration, baseline severity of gambling and publication year significantly moderated effect sizes for at least some of these outcome measures. Author conflict of interest, placebo run-in, gender split, severity scale choice, age of participants or unbalanced randomisation did not moderate effect sizes. Nocebo effects leading to drop out from the trial were observed in 6% of participants in trials involving antipsychotics, while this was less for other medication types.

Placebo effects in trials of pharmacological treatment of gambling disorder are large, and there are several moderators of this effect. Nocebo effects were measureable and may be influenced by medication class being studied. Practical implications of these new findings for the field are discussed, along with recommendations for future clinical trials.

Binge eating disorder (BED) is the most common eating disorder, and is associated with significant comorbidity, with university students being particularly vulnerable. We aimed to assess associations of BED with a wide range of comorbidities and measures of impulsivity and compulsivity in university students, to gain better understanding of its prevalence, correlates and pathophysiology.

We carried out an internet-based survey, assessing presence of BED using a validated structured self-report diagnostic tool, demographics, substance use, impulsive behaviors, psychiatric history, and measures of impulsivity and compulsivity. Approximately 10 000 students were invited to take part. Group differences between students with current BED and students without BED were investigated.

A total of 3415 students completed the survey, with 83 (2.4%) screening positive for BED. BED was associated with female gender, hazardous/harmful alcohol use, depression and anxiety symptoms, low self-esteem, post-traumatic stress disorder, attention-deficit/hyperactivity disorder, treatment for psychological/emotional problems (including prescribed medication) and trait impulsivity and compulsivity. However, the largest effect sizes were evident for associations with trait impulsivity and compulsivity.

The associations of BED with trait impulsivity and compulsivity implicate these latent phenotypes in its pathophysiology. The identified links between BED and a wide range of mental disorders highlight the need to screen for disordered eating in student populations, including when students present with other mental health conditions.