| While the exact causes of ADHD (Attention Deficit | | | | behavioral problems. Exposure to lead, which is found |
| Hyperactivity Disorder) remain unknown, researchers | | | | in the paint and pipes of older buildings, has been linked |
| have identified several factors that may play a role. | | | | to disruptive behavior, violence, and shortened attention |
| Heredity | | | | spans. |
| Studies show that ADHD tends to run in families. | | | | Exposure to PCBs (polychlorinated biphenyls) in infancy |
| About one in four children with ADHD have at least | | | | may also increase a child's risk of developing ADHD |
| one relative with the disorder (Centers for Disease | | | | (Centers for Disease Control and Prevention, 2008.) |
| Control and Prevention, 2007). Also, recent studies of | | | | Altered Brain Function And Anatomy |
| twins link genes with ADHD. | | | | Brain scans have revealed important differences in the |
| Prenatal Exposure To Smoking, Drug Use and Other | | | | structure and brain activity of people with ADHD. |
| Toxins | | | | There appears to be less activity in the areas of the |
| Pregnant women who smoke are at increased risk of | | | | brain that control activity and attention. What is unkown |
| having children with ADHD (Centers for Disease | | | | is whether this is a direct function of the condition, |
| Control and Prevention, 2008.) In addition, alcohol or | | | | something that develops over time, or both. |
| drug abuse during pregnancy may reduce activity of | | | | What Does Not Cause ADHD |
| the neurons that produce neurotransmitters. | | | | Research does not support popularly held myths that |
| Pregnant women who are or were exposed to | | | | ADHD is caused by consuming too much sugar, |
| environmental poisons such as polychlorinated | | | | watching too much television, poor parenting, or social |
| biphenyls (PCBs) may be more likely to have children | | | | and environmental factors such as poverty or family |
| with symptoms of ADHD. (PCBs are industrial | | | | upheaval. Of course, these environmental factors may |
| chemicals that were widely used up until the 1970s.) | | | | worsen the symptoms of ADHD but the evidence is |
| Childhood Exposure To Toxins | | | | not strong enough to conclude that they are the main |
| Preschool children exposed to environmental hazards | | | | causes of ADHD. |
| and toxins are at increased risk of developmental and | | | | |