Dietary supplements for aggressive behaviour in people with intellectual disabilities: A randomised controlled crossover trial

Abstract

Background: Aggressive incidents are common in people with intellectual disabilities.Therefore, we aimed to assess whether supplementation of multivitamins, minerals, and omega-3 fatty acids (FA) reduces aggressive incidents. Methods: We conducted a randomised, triple blind, placebo controlled, single crossover intervention trial. People with intellectual disabilities or borderline intellectual functioning, between 12 and 40 years of age, and showing aggressive behaviour were included. Participants received either a daily dose of dietary supplements, or placebo. Primary outcome was the number of aggressive incidents, measured using the Modified Overt Aggression Scale (MOAS).Results: there were 113 participants (placebo, n = 56), of whom 24 (placebo, n = 10) participated in the crossover phase of the trial. All 137 trajectories were included in the analyses. There was no significant difference in mean number of aggressive incidents per day between those assigned to supplements and those who received placebo (rate ratio = 0.93: 95% Confidence Interval [CI] = 0.59-1.45). Conclusion:In this pragmatic trial, we did not find significant differences in the outcomes between the supplement and placebo arms. The COVID-19 pandemic started midway through our trial, this may have affected the results.

Nutritional factors associated with aggression

“…In forensic psychiatric settings, it has been suggested that studies on nutritional supplementation consider the use of psychotropic medications. Recent trials on psychiatric inpatients and individuals with intellectual disabilities have proposed that the lack of beneficial effects from nutritional supplementation may be attributable to a possible ceiling effect due to the existing use of antipsychotics in most patients ( 16 , 73 ).…”

“…To address these nutrient deficiencies, some randomized controlled trials (RCTs) have found broad-range supplements that comprise various vitamins, minerals, and macronutrients to be associated with reductions in aggressive and rule-breaking behavior in children with ADHD ( 10 ) and conduct problems ( 11 ), and in incarcerated samples ( 12 – 14 ). Others, however, reported that multivitamin, mineral, and omega-3 supplementation did not significantly reduce aggressive incidents in psychiatric inpatients ( 15 ) or in aggressive individuals with intellectual disabilities ( 16 ). The finding that very few studies examined the same composition of nutritional supplementation has resulted in a call for investigations of supplement content and dosage ( 17 ).…”