Design and procedure
intellectual disabilities
ADVERSE EVENTS, BLIND
This study was a pragmatic, randomised, triple‐blind, placebo controlled, multicentre and crossover intervention study to investigate the effect of dietary supplements on aggressive behaviour among people with intellectual disabilities and borderline intellectual functioning. The study was registered at the Clinical Trials Register (NCT03212092). Approval for conducting the study was granted by the Medical Ethics Committee of the Leiden University Medical Center (LUMC) (NL60839.058.17). The coordinating centre was the LUMC department of psychiatry, and the data was collected at six care organisations between 11 April 2018 and 1 February 2021. Participants first entered a run‐in phase and received placebo supplements for 2 weeks. Thereafter, they were randomised and included in the 16‐week study. After completion, they were asked to participate in the crossover trial, and after a new informed consent procedure and a washout period of at least 2 weeks, they would repeat the study in a different treatment arm, while the study pharmacist maintained the blind to treatment allocation. Support staff offered the supplements and reported incidents daily. Trained research assistants collected baseline and endpoint data from the support staff, and if possible, from the participants. On a weekly basis, they monitored incident reports and adverse events collected by support staff. The participants received a gift voucher of 5 euros twice for their contribution to providing baseline and endpoint data.