The Effect of Dietary Supplementation on Aggressive Behaviour in Australian Adult Male Prisoners: A Feasibility and Pilot Study for a Randomised, Double Blind Placebo Controlled Trial

Abstract

This study aimed to assess the feasibility of conducting a nutrition trial in adult male prisoners. Adult male prisoners were recruited for a 16-week randomised control trial comparing the effect of ingestion of omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) and multivitamin supplements versus placebo on aggressive behaviour. The baseline and post-intervention assessments from the participant blood samples were the erythrocyte n-3 LCPUFA levels as well as measures of aggressive behaviour determined through institutional records of misconduct (IRM), the Inmate Behaviour Observation Scale (IBOS), and questionnaires. A total of 136 adult male prisoners consented to the study with a retention rate of 60%, and 93% of blood samples were successfully collected. The IRM and IBOS scores were collected for 100% of participants, whilst 82-97% of participants completed the questionnaires. From the baseline data, the Odds Ratio shows that prisoners are 4.3 times more likely to have an IBOS >2 if they are below the 6% cut off on the omega-3 index. Both groups improved across all outcome measures and, at the current sample size, no significant differences were seen between them. A power calculation suggests a total sample size of 600 participants is required to detect the effects of this dietary supplementation, and that this supplementation study is feasible in a Correctional Centre. Important criteria for the exclusion and consideration of logistics and compliance are presented.

Keywords: aggressive behaviour; diet; n-3 LCPUFA; omega-3 index; prisoners.

Figure 1

CONSORT flow diagram of recruitment, follow-up, assessment of the whole cohort, and assessment of the subset of aggressive participants, as defined by an Inmate Behaviour Observation Scale (IBOS) of 1 or greater at baseline.

Figure 2

Distribution of the Omega-3 Index (A) at baseline (n = 131), (B) at the completion of the study (n = 75), and (C) as a change between these two time points for participants who completed the intervention (n = 75).

Figure 3

Percentage of participants who improved in aggression in (A) the whole cohort (n = 75) and (B) the subset of participants considered aggressive at baseline, as defined by a score of 1 or greater on the Inmate Behaviour Observation Scale (IBOS) (n = 29). Improvement in behaviour was measured as a decrease in the IBOS, a decrease in the number of institutional records of misconduct (IRM) over four weeks at the end of the trial, a decrease of at least five points in the Aggression Questionnaire’s Total scale (AQ Total), and a decrease of at least five points in the Brown Attention Deficit Disorder Total scale (BADDS Total). No significant differences were observed for the whole cohort or the aggressive subset.