A medical study done on rats showed that excessive dose of fluoride can trigger ADD and ADHD-type behavioral changes. While this does not necessarily indicate a similar risk in humans, it is certainly a possibility, even though not immediate. 

If a child is suffering from brain injury or any kind of mental trauma, it is likely that he/she will develop ADD or ADHD symptoms. It can lead to highly disruptive behavior. A small percentage of studies also show that such children may suffer a traumatic brain injury in the later years.

Some medical studies have proven that food allergies in children can trigger ADD or ADHD symptoms. There is more research needed to substantiate this but at the moment, it is a popular belief that nutritional deficiencies and food sensitivities does play a role in triggering either ADD or ADHD.

It is also believed that eating sugar can cause hyperactive behavior but there is no research work to substantiate this claim yet. According to the National Institute of Mental Health (NIMH), a large number of studies are undertaken every year to prove that sugar and sugar substitutes are not connected with behavioral and learning incapacity issues in ADD and ADHD children. 

The use of food preservatives or food coloring in excessive quantity might cause ADD or ADHD in children. Hunter explains that the, “effects of food additives are probably negligible for most children with ADHD, but some children may be more sensitive than others.” A study undertaken in Britain shows a link between ADD, ADHD and food additives. This is the reason people are generally made aware to not consume food with excessive amount of coloring or foods that are full of additives. 

If the maternal or the paternal family has a past history of ADD or ADHD among the near or distant family members, it is highly probable that the associated ADD or ADHD genes can trigger itself in the future generations of the family. Therefore, ADD or ADHD is a hereditary behavioral problem too. Research studies to identify ADD and ADHD genes are underway currently. 

Again, lead is an environmental toxin. If children in preschool are exposed to lead, it causes behavioral and developmental problems. This pollutant is generally found in old buildings, water and paint. Children exposed to high amounts of lead are generally known to have disruptive or violent behavior and a short attention span, symptomatic of ADD and ADHD. 

A study undertaken at Harvard University shows that children who are heavily exposed to pesticides run a greater risk of developing ADD or ADHD. The researchers identified the high level of pesticides found in the urine of children and concluded that such high pesticide presence doubles the chances of developing ADD or ADHD in the later stages of development. 

Women who regularly take drugs and alcohol whilst pregnant have a greater chance of having children with ADD or ADHD because the drugs and alcohol weaken the nerve cells of the woman and the fetus alike. 

Women who undergo a difficult pregnancy that hampers fetal development are generally known to have children with this disorder. Doctors cite complications like bleeding before delivery, a long delivery time, high blood pressure, or anything else that impacts the supply of oxygen before the baby’s birth. All the above are attributed to cause ADD or ADHD later in the development of the child.