Several studies have shown that the excessive consumption of sugar and food additives can cause hyperactivity and aggression in children. Other researchers have found that the typical diet ingested by many American teenagers (which includes a high percentage of vitamin and mineral deficient and sugarand additive-laden junk foods) can lead to symptoms of beriberi such as increased irritability and aggressiveness. Excessive amounts of phosphate are also thought to cause brain misfunction. Research has also examined (1) smoking by pregnant women, which increases the risk of small birth size and prematurity and can result in impaired intellectual level; and (2) high levels of lead in the body, and other metals (mercury, cadmium, and copper) which may possibly be neurotoxic. Remedial techniques focus on specific diet changes. Approximately 50 references are supplied.