The effect of docosahexaenoic acid on aggression in elderly Thai subjects--a placebo-controlled double-blind study

Docosahexaenoic acid (DHA) administration controls extraggression (aggression against others) in young subjects under psychological stress. However, it is not known whether its administration affects extraggression of elderly subjects. Forty Thai subjects of 50-60 years of age (22 males and 18 females) were recruited from Silpakorn University and nearby villages. They were allocated to the control and DHA groups in a double-blind fashion, and took 10 mixed plant oil capsules and 10 DHA capsules (1.5g DHA/day) for 2 months, respectively. Extraggression was measured with a psychological test (PF Study) at the beginning and end of the study. Just prior to the PF Study at the end of the study, subjects were asked to watch a stressful videotape as a stressor component. The average DHA intake from food was 150-160mg/day. In the group of university employees, extraggression did not change over time with placebo, whereas extraggression significantly decreased (31 +/- 13 to 24 +/- 13%, P = 0.04 by the paired-t test, P = 0.04 by ANOVA). In the group of villagers, there was no significant difference between the control and DHA groups in extraggression. The DHA administration favorably controlled extraggression in at least elderly white-collar workers. The daily intake of 150-160 mg/day of DHA was not enough to control extraggression.