Omega-3 polyunsaturated fatty acids induced gender-specific changes in activity, impulsiveness and attention in an animal model of Attention- Deficit/Hyperactivity Disorder

Abstract

Background: It is argued that omega-3 (n-3) polyunsaturated fatty acids (PUFAs) may influence Attention-Deficit/Hyperactivity Disorder (ADHD) symptoms and/or development by affecting the lipid composition of neuromodulator systems such as the dopamine system which is believed to be hypo-functioning in children with ADHD. A validated animal model of ADHD was used to explore whether a long-chain n-3 PUFA-enriched chow would exert any positive effects on behavioral measures of activity, impulsiveness and attention.

Method: A total of 36 spontaneously hypertensive rats (SHRs) were tested in this study. One group (8 males and 7 females) received a long-chain n-3 PUFA-enriched chow with a balanced omega-6/omega-3-ratio and the control group (11 males and 10 females) received standard lab-chow. Both SHR dams and offspring were exposed to the feeding conditions. The offspring were tested using a variable reinforcement schedule designed to measure activity level, impulsiveness and attention. In addition, a measure of general activity was derived from video-recorded data.

Results: PUFA-treatment tended to interact with gender and reduced activity, impulsiveness and improving attention in male-SHRs while female-SHRs showed no effect or an increased activity, impulsiveness and reduced attention on operant measures. Results from video- recorded activity revealed that both genders reduced their general activity in the beginning of each session and that general activity was different across sessions than the results obtained from the operant measure of activity.

Conclusion: Long-chain n-3 PUFA-treatment administered to both SHR dams and offspring induced two distinct sets of behavioral changes in the offspring. One gender-specific effect showed reduced reinforcer-controlled activity, impulsiveness and improved attention in male- SHRs and none or opposite effects in female-SHRs. Another effect showed reduced exploratory activity in both genders. It is hypothesized that the n-3 PUFA-treatment might have exerted gender-specific effects on neural systems regulating reinforcement-controlled behavior and effects on neural systems regulating exploratory activity in both genders.