An analysis of blinding success in a randomised controlled trial of fish oil omega-3 fatty acids.

INTRODUCTION: Incidental reports collected in clinical trials suggest that amongst participants, omega-3 fatty acids derived from fish oil ('omega-3') may be difficult to blind. MATERIALS AND METHODS: We conducted a systematic evaluation of blinding success in a 24-week trial of omega-3 versus an oil-based placebo. Within 1 week of supplement commencement (Week 1), a blinding questionnaire was completed by 131 children enrolled in a trial of omega-3 for the treatment of disruptive behaviour disorders. A version of the questionnaire was also completed by their parents at Week 1, and by the children at the end of supplement administration (Week 24). RESULTS: Participants were unable to differentiate omega-3 from placebo, and accuracy did not improve as a function of: the confidence of guesses, reason for guesses, notice of any change, beliefs about what should change, or time. Child and parent guesses also showed high concordance. CONCLUSION: Taken together, these data provide strong evidence that the identity of omega-3 can be blinded to participants.

A randomized, controlled, crossover trial of fish oil treatment for impulsive aggression in children and adolescents with disruptive behavior disorders.

OBJECTIVE: Epidemiological research links aggression to low serum concentrations of omega-3 fatty acids, such as those found in fish oil. However, no studies have specifically examined whether fish oil supplementation can reduce the frequency and severity of impulsive aggression in children with disruptive behavior disorders. METHODS: Children presenting with impulsive aggression and meeting research criteria for diagnosis of disruptive behavior disorders were randomized to receive either: 1) Fish oil capsules (4 g daily) for 6 weeks followed by placebo (identical-looking capsules) for 6 weeks; or 2) placebo for 6 weeks, followed by fish oil for 6 weeks, in a double-blind, crossover design. Primary outcomes were the Children's Aggression Scale and the Modified Overt Aggression Scale. Secondary outcomes included emotional and behavioral functioning (Strengths and Difficulties Questionnaire [SDQ]), hyperactivity symptoms (Attention-Deficit/Hyperactivity Disorder [ADHD] Rating Scale), family functioning (Family Assessment Device), and cognitive functioning (Stop Signal Task, Trail-Making Task, and Eriksen Flanker Task). Serum concentrations of omega-3 and omega-6 fatty acids were measured at baseline, and at 6 and 12 weeks. RESULTS: Twenty-one children participated (81% male; mean age 10.3±2.2 years; range 7-14). Fish oil treatment increased serum concentrations of eicosapentanoic acid (F=14.76, p<0.05) and total omega-3s (F=20.56, p<0.05), but did not influence primary ratings of aggression. In fact, a trend suggested that fish oil worsened a secondary measure of aggression (SDQ Conduct Subscale, F=4.34, p=0.06). Fish oil treatment was associated with an improvement in one rating of hyperactivity (SDQ Hyperactivity Subscale, F=2.22, p<0.05), but did not influence any other outcome measures. CONCLUSIONS: These findings suggest that fish oil treatment does not improve aggression in children with disruptive behavior disorders.