In the past, research has not shown any link between Attention Deficit Hyperactivity Disorder and food dyes. Newer studies show that synthetic preservatives and artificial coloring agents can make the symptoms of ADD and ADHD worse. The older studies were inclonclusive on this point, perhaps because the clinical methods of measuring this behavior were inappropriate. Parents' reports of food additives proved to be better indicators whether additives were present than clinical tests. Several major studies show academic performance increased and disciplinary problems decreased in large non-ADD student populations when artificial ingredients and artificial coloring were eliminated from school food programs.