Attention Deficit Disorder is caused by a chemical imbalance in the brain. There appears to be a deficiency in the brains ability to produce or use certain chemicals called transmitter substances or neurotransmitters. The theory is that a shortage of certain neurotransmitters results in the brain being under-stimulated, therefore it's deficient in regulating its own activities such as attention. Attention Deficit Disorder is characterized by a number of common symptoms. The symptoms are short attention span or distractibility, impulsiveness ....