Could polyunsaturated fatty acids deficiency explain some dysfunctions found in ADHD? Hypotheses from animal research.

OBJECTIVES: The objective is to evaluate possible mechanisms explaining the link between polyunsaturated fatty acid (PUFA) deficiencies and ADHD, based on findings from animal research. METHOD: The authors consulted peer-reviewed publications from the last 10 years (Medline and resulting reference lists). RESULTS: PUFA deficiency in rodents results in behavioral changes (increased motor activity and decreased learning abilities) and dysregulations of monoamine neurotransmission. Behavioral improvement following a PUFA recovery diet is observed, but recovery of brain monoamine dysregulation is not fully demonstrated. Anti-inflammatory processes could damage neural membranes, but the direct link with ADHD model is not documented. Synaptic growth and neurogenesis impairment could account for working memory dysregulations, but research is at its early start. CONCLUSION: Induced PUFA deficiencies in animals show several noteworthy similarities with brain dysregulations seen in ADHD human children. However, the mechanisms of partial recovery after PUFA supplementation are not fully understood, and rigorous clinical trials have yet to show PUFA supplementation is an effective complementary treatment for ADHD.

Can multi-micronutrient food fortification improve the micronutrient status, growth, health, and cognition of schoolchildren? A systematic review.

Micronutrient deficiencies compromise the health and development of many school-age children worldwide. Previous research suggests that micronutrient interventions might benefit the health and development of school-age children and that multiple micronutrients might be more effective than single micronutrients. Fortification of food is a practical way to provide extra micronutrients to children. Earlier reviews of (multiple) micronutrient interventions in school-age children did not distinguish between supplementation or fortification studies. The present review includes studies that tested the impact of multiple micronutrients provided via fortification on the micronutrient status, growth, health, and cognitive development of schoolchildren. Twelve eligible studies were identified. Eleven of them tested the effects of multiple micronutrients provided via fortified food compared to unfortified food. One study compared fortification with multiple micronutrients to fortification with iodine alone. Multi-micronutrient food fortification consistently improved micronutrient status and reduced anemia prevalence. Some studies reported positive effects on morbidity, growth, and cognitive outcomes, but the overall effects on these outcomes were equivocal.

The impact of polyunsaturated fatty acids in reducing child attention deficit and hyperactivity disorders.

OBJECTIVES: To review the impact of polyunsaturated fatty acids (PUFA) in reducing ADHD symptoms in children. METHODS: Peer-reviewed experimental literature published from 1980 to Mai 2009 is consulted (Psychinfo, Medline, and resulting reference lists). RESULTS: Placebo-controlled studies with ADHD or hyperactive children show no effects on behaviors or cognition when only n-6 (omega-6) PUFA, only docosahexaenoic acid (DHA), or n-6 and n-3 (omega-3) short-chain PUFA are supplemented. Yet three out of four studies suggest that a combination of long-chain n-3 and n-6 fatty acids (DHA, eicosapentaenoic acid [EPA], and gamma-linolenic acid [GLA]) supplemented daily for 3 to 4 months could lead to a reduction in ADHD symptomatology. Results on cognitive outcomes are inconsistent. CONCLUSIONS: Evidence is too limited to reach definitive conclusions but suggests that research on the impact of long-chain PUFA (n-3 and n-6) should continue with special focus on individual differences (genetic and fatty acid markers), mechanisms (brain imaging), and new enhanced methods of systematic observations of behaviors.

Traveling with cognitive tests: testing the validity of a KABC-II adaptation in India.

The authors evaluated the adequacy of an extensive adaptation of the American Kaufman Assessment Battery for Children, second edition (KABC-II), for 6- to 10-year-old Kannada-speaking children of low socioeconomic status in Bangalore, South India. The adapted KABC-II was administered to 598 children. Subtests showed high reliabilities, the Cattell-Horn-Carroll model underlying the original KABC-II was largely replicated, and external relations with demographic characteristics and an achievement measure were consistent with expectations. The subtests showed relatively high loadings on the general cognitive factor, presumably because of the high task novelty and, hence, cognitive complexity of the tests for the children. The findings support the suitability and validity of the KABC-II adaptation. The authors emphasize that test adaptations can only be adequate if they meet both judgmental (qualitative) and statistical (quantitative) adaptation criteria.

Multiple micronutrient supplementation for improving cognitive performance in children: systematic review of randomized controlled trials.

BACKGROUND: Although multiple micronutrient interventions have been shown to benefit children's intellectual development, a thorough evaluation of the totality of evidence is currently lacking to direct public health policy. OBJECTIVE: This study aimed to systematically review the present literature and to quantify the effect of multiple micronutrients on cognitive performance in schoolchildren. METHODS: The Institute for Scientific Information Web of Knowledge and local medical databases were searched for trials published from 1970 to 2008. Randomized controlled trials that investigated the effect of > or =3 micronutrients compared with placebo on cognition in healthy children aged 0-18 y were included following protocol. Data were extracted by 2 independent researchers. The cognitive tests used in the trials were grouped into several cognitive domains (eg, fluid and crystallized intelligence), and pooled effect size estimates were calculated per domain. Heterogeneity was explored through sensitivity and meta-regression techniques. RESULTS: Three trials were retrieved in children aged <5 y, and 17 trials were retrieved in children aged 5-16 y. For the older children, pooled random-effect estimates for intervention were 0.14 SD (95% CI: -0.02, 0.29; P = 0.083) for fluid intelligence and -0.03 SD (95% CI: -0.21, 0.15; P = 0.74) for crystallized intelligence, both of which were based on 12 trials. Four trials yielded an overall effect of 0.30 SD (95% CI: 0.01, 0.58; P = 0.044) for academic performance. For other cognitive domains, no significant effects were found. CONCLUSIONS: Multiple micronutrient supplementation may be associated with a marginal increase in fluid intelligence and academic performance in healthy schoolchildren but not with crystallized intelligence. More research is required, however, before public health recommendations can be given.

Effect of fortification with multiple micronutrients and n-3 fatty acids on growth and cognitive performance in Indian schoolchildren: the CHAMPION (Children's Health and Mental Performance Influenced by Optimal Nutrition) Study.

BACKGROUND: Fortification with multiple micronutrients has been shown to improve growth and cognitive performance among children in developing countries, but it is unknown whether higher concentrations are more effective than lower concentrations. OBJECTIVE: We compared the effect of 2 different concentrations of a combination of micronutrients and n-3 (omega-3) fatty acids on indicators of growth and cognitive performance in low-income, marginally nourished schoolchildren in Bangalore, India. DESIGN: In a 2-by-2 factorial, double-blind, randomized controlled trial, 598 children aged 6-10 y were individually allocated to 1 of 4 intervention groups to receive foods fortified with either 100% or 15% of the Recommended Dietary Allowance of micronutrients in combination with either 900 mg alpha-linolenic acid plus 100 mg docosahexaenoic acid or 140 mg alpha-linolenic acid for 12 mo. Anthropometric and biochemical assessments were performed at baseline and 12 mo. Cognitive performance was measured at baseline and at 6 and 12 mo. RESULTS: The high micronutrient treatment significantly improved linear growth at 12 mo (0.19 cm; 0.01, 0.36) and short-term memory at 6 mo (0.11 SD; 0.01, 0.20) and was less beneficial on fluid reasoning at 6 (-0.10 SD; -0.17, -0.03) and 12 (-0.12 SD; -0.20, -0.04) mo than was the low micronutrient treatment, whereas no differences were observed on weight, retrieval ability, cognitive speediness, and overall cognitive performance. No significant differences were found between the n-3 treatments. CONCLUSIONS: The high micronutrient treatment was more beneficial for linear growth than was the low micronutrient treatment. However, with some small differential effects, higher micronutrient concentrations were as effective as lower concentrations on cognitive performance. This trial was registered at clinicaltrials.gov as NCT00467909.

Effect of a 12-mo micronutrient intervention on learning and memory in well-nourished and marginally nourished school-aged children: 2 parallel, randomized, placebo-controlled studies in Australia and Indonesia.

BACKGROUND: Little is known about the combined effect of micronutrients and essential fatty acids on cognitive function in school-aged children. OBJECTIVE: We assessed the effect of micronutrients, long-chain n-3 fatty acids, or both on indicators of cognitive performance in well-nourished and marginally nourished school-aged children. DESIGN: Two 2-by-2 factorial randomized controlled double-blind trials were performed home-based in Adelaide, South Australia, and at 6 primary schools in Jakarta, Indonesia. A total of 396 children (aged 6-10 y) in Australia and 384 children in Indonesia were randomly allocated to receive a drink with a micronutrient mix (iron, zinc, folate, and vitamins A, B-6, B-12, and C), with docosahexanoic acid (DHA, 88 mg/d) and eicosapentaenoic acid (EPA, 22 mg/d), or with both or placebo 6 d/wk for 12 mo. Biochemical indicators were determined at baseline and 12 mo. Cognitive performance was measured at baseline, 6 mo, and 12 mo. RESULTS: The micronutrient treatment significantly improved plasma micronutrient concentrations in Australian and Indonesian children. DHA+EPA treatment increased plasma DHA and total plasma n-3 fatty acids in both countries. The micronutrient treatment resulted in significant increases in scores on tests representing verbal learning and memory in Australia (estimated effect size: 0.23; 95% CI: 0.01, 0.46). A similar effect was observed among Indonesian girls (estimated effect size: 0.32; 95% CI: -0.01, 0.64). No effects were found on tests measuring general intelligence or attention. No effects of DHA+EPA on the factors of cognitive tests were observed. CONCLUSION: In well-nourished school-aged children, fortification with multiple micronutrients can result in improvements in verbal learning and memory.

Phonological coding in reading of deaf children: Pseudohomophone effects in lexical decision.

The purpose of this study was to find new evidence for phonological coding in written word recognition among deaf Dutch children. A lexical decision task was presented to 48 severely and profoundly deaf children aged from 6 years 8 months to 13 years 5 months, and a control group of Grade 1 hearing children matched on written word recognition. Sixteen pseudohomophones were introduced, closely matched on orthographic similarity with 16 control pseudo-words. Both hearing children and deaf children made significantly more mistakes on pseudohomophones than on control pseudo-words. Although pseudohomophony effects were smaller for deaf than for hearing participants, the findings were taken as evidence that deaf children also used phonological coding during written word recognition.