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Nutrition, Neurotoxicants and Aggressive Behaviuour
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Antisocial behaviour, such as violence, is explained not only by the social environment, as was long believed. Also nutrients and neurotoxicants might play a role. Whether this is the case was studied in this thesis.
In two empirical studies possible relations between nutrients and behaviour were investigated. In the first study, levels of nutrients in blood samples of forensic psychiatric patients were measured. Low levels of omega-3 fatty acids appeared to occur mainly in aggressive patients. In a second study, young detainees were provided with food supplements (multi-vitamins and fish oil). As compared to detainees in a placebo group their antisocial behaviour decreased.
A literature search was conducted to find out if environmental neurotoxicants and criminal behaviour are related. Evidence indicates that lead in the environment decreases intelligence in children and might cause violent behaviour later in life. Studying other environmental pollutants on these effects is recommended.
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... In the case of lead, the evidence fulfills the majority of these conditions. For a detailed elaboration on this line of evidence see Nevin (2009) andZaalberg (2015). ...
Objective: Low levels of docosahexaenoic acid, a polyunsaturated fatty acid, and elevated ratios of omega-6/omega-3 fatty acids are associated with major depression and, possibly, suicidal behavior. Predicting risk of future suicidal behaviors by essential fatty acid status merits examination. Method: Plasma polyunsaturated fatty acid levels in phospholipids were measured in 33 medication-free depressed subjects monitored for suicide attempt over a 2-year period. Survival analysis examined the association of plasma polyunsaturated fatty acid status and pathological outcome. Results: Seven subjects attempted suicide on follow-up. A lower docosahexaenoic acid percentage of total plasma polyunsaturated fatty acids and a higher omega-6/omega-3 ratio predicted suicide attempt. Conclusions: A low docosahexaenoic acid percentage and low omega-3 proportions of lipid profile predicted risk of suicidal behavior among depressed patients over the 2-year period. If confirmed, this finding would have implications for the neurobiology of suicide and reduction of suicide risk.
Zinc (Zn) is essential for synthesis of coenzymes that mediate biogenic-amine synthesis and metabolism. Zn from vesicles in presynaptic terminals of certain glutaminergic neurons modulates postsynaptic N-methyl-d-aspartate (NMDA) receptors for glutamate. Large amounts of Zn released from vesicles by seizures or ischemia can kill postsynaptic neurons. Acute Zn deficiency impairs brain function of experimental animals and humans. Zn deficiency in experimental animals during early brain development causes malformations, whereas deficiency later in brain development causes microscopic abnormalities and impairs subsequent function. A limited number of studies suggest that similar phenomena can occur in humans.
Blood lead levels in children have declined, and the level of concern specified by the Centers for Disease Control and Prevention now is 10 μg/dL. It is not clear, however, whether cognitive deficits consequent to lead exposure are a problem at blood lead levels less than 10 μg/dL. This study estimated blood lead concentrations in 172 children at ages 6, 12, 18, 24, 36, 48, and 60 months. At ages 3 and 5 years, the children were tested with the Stanford-Binet Intelligence Scale, an instrument that evaluates vocabulary, spatial pattern analysis, quantitative ability, and memory. Intelligence quotient (IQ) was related to blood lead levels after adjusting for maternal IQ, quality of the home environment, and other potentially confounding factors. Mean blood lead levels were lowest at age 6 months (3.4 μg/dL) and maximal at age 2 years (9.7 μg/dL). By age 5, the mean level was 6 μg/dL. The lifetime average blood lead level was 7.7 μg/dL at age 3 years and 7.4 μg/dL at age 5. The proportions of children with peak lead levels below 10 μg/dL were 57.0% and 55.8% at ages 3 and 5 years, respectively. At both these ages, the mean IQ (composite score) was approximately 90. After adjusting for numerous covariates, IQ correlated inversely and significantly with blood lead concentration. An increase in the lifetime average blood lead level of 1 μg/dL correlated with a change in IQ of -0.46. The estimated overall difference in IQ for each 1-μg/dL increase in lifetime average lead level was -1.37 points. Other significant predictors of IQ included maternal IQ, material income, and the child's birth weight. These findings suggest that substantially more children in the United States undergo adverse cognitive change from environmental exposure to lead than was previously thought. Primary prevention is essential in view of the lack of effective treatment for children with moderate blood lead elevations.
Optimal neurodevelopment of the fetus depends in part on an adequate supply of docosahexaenoic acid (DHA), an omega-3 essential fatty acid that is abundant in seafood. A diet lacking in seafood could impair development because of too little long-chain omega-3 fatty acids such as DHA and eicosapentaenoic acid. Nevertheless, federal agencies have recommended limiting seafood consumption by parturients to 340 g per week so as to avoid exposing the fetus to trace amounts of neurotoxins. The investigators used data from the Avon Longitudinal Study of Parents and Children to clarify the influence of maternal seafood intake during pregnancy on developmental, behavioral, and cognitive outcomes at ages 6 months to 8 years. Participating were 11,875 pregnant women who completed a food frequency questionnaire at 32 weeks’ gestation. Children were assessed using items from the Denver Developmental Screening Test as well as the Strengths and Difficulties Questionnaire and verbal and performance intelligence quotient (IQ) scores. About one-third of women in the study ate up to 340 g of seafood each week, whereas 12% ate no seafood at all while pregnant. Just under one-fourth of women ate more than 340 g weekly. Low seafood consumption correlated with a socially disadvantageous setting including low educational levels and also with less than ideal lifestyles. After adjusting for these and other variables, eating less than 340 g of seafood each week correlated with an increased likelihood of a verbal IQ in the lowest quartile. The odds ratio (OR) for women eating no seafood, compared with those eating more than 340 g weekly, was 1.48 with a 95% confidence interval (CI) of 1.16–1.90. For women eating some seafood but less than 340 per week the OR for low verbal intelligence was 1.09 (95% CI, 0.92–1.29). Low seafood intake also was associated with suboptimal outcomes for prosocial behavior, fine motor function, communicative ability, and social development scores. In each instance, the risk of a suboptimal outcome increased with declining levels of seafood intake. Fewer than 2% of women in this study consumed fish oil supplements while pregnant. Outcomes of infants whose mothers took a supplement but did not eat seafood were similar to those in infants whose mothers did eat seafood. No trend toward benefit in any neurodevelopmental domain was observed when the weekly seafood intake was less than 340 g. These findings suggest that limiting weekly seafood consumption to less than 340 g may have adverse effects on early childhood neurodevelopment. The authors believe that a lack of essential nutrients is more harmful than potential exposure to the trace contaminants present in some seafood.