Doctors and researchers are unsure what causes attention deficit hyperactivity disorder, also called ADHD. Several discounted theories about the causes of ADHD include sugar and brain injuries, according to HealthyPlace. ADHD symptoms, including forgetfulness, lack of focus, poor organizational skills and extremely high energy, may be due to several causes, all still under research and investigation. MayoClinic.com suggests, however, that the activity and structure of the brain in individuals with ADHD is different from those without ADHD.
Genetic Causes
ADHD seems to run in families. Among identical twins, reports the American Academy of Pediatrics, one twin having ADHD puts the other twin at high risk for the disorder. Relatives of individuals with ADHD have a five times greater risk of having ADHD, and siblings of a child with ADHD have a 30 percent increased chance of having ADHD. HealthyPlace reports that researchers continue to study possible genetic links to attention deficit hyperactivity disorder. The Attention Deficit Hyperactivity Disorder Molecular Genetics Network provides a way for researchers to share information about possible genetic connections to ADHD.
Environmental Causes
Researchers, according to the University of Maryland Medical Center, are investigating several environmental factors that appear to increase the potential for an individual to have ADHD. A woman's use of drugs, alcohol or cigarettes during pregnancy may impact her unborn child, reducing nerve cell activity. In addition, various toxins in the environment may affect brain development. For example, exposure to polychlorinated biphenyls, or PCBs, according to MayoClinic.com, increases a pregnant woman's likelihood of having a child with symptoms of attention deficit hyperactivity disorder. Infant exposure to polychlorinated biphenyls also increases the risk of developing ADHD. Drugs, including crack and cocaine also appear to disrupt normal brain development. Another environmental factor, childhood exposure to lead, increases the possibility for mental health issues including violent behavior and decreased attention. Lead is found in older buildings, especially in paint and plumbing fixtures.
Brain Glucose Causes
There may be a connection between attention deficit hyperactivity disorder and levels of glucose in the brain. The University of Maryland Medical Center reports that individuals with ADHD use less glucose, the brain's main source of energy, than people without ADHD. The measured areas of the brain included areas that control attention and inhibit impulses.
