Attention deficit hyperactivity disorder (ADHD) is now recognized as a common childhood disorder that can continue into adulthood. While diagnosing ADHD has become more common, understanding ADHD causes remains a work in progress.
“There is no single test for diagnosing ADHD and there is no single ADHD cause,” notes Loren R. Dribinsky, MD, a psychiatrist at the Lahey Clinic in Burlington, Mass.
“We know that genes are one of the most important ADHD causes because ADHD runs strongly in families,” adds Scott J. Hunter, PhD, director of pediatric neuropsychology at the University of Chicago. “What we don’t know is how other possible factors influence those genes or make children’s brains more vulnerable to ADHD.”
Many theories about ADHD causes have been considered over the years, including:
• Lack of good parenting
• Stressful family situations
• Excessive exposure to TV and video games
• Lack of structure at school
Quite a few of these theories have been abandoned and new theories have replaced them. “One reason why we don’t know all the ADHD causes is that we can study genes and brain changes, but it is very hard to study environmental triggers,” explains Dr. Dribinsky.
Though we don’t completely understand why some children are more likely to have ADHD, studies show that regions of the brain affected by ADHD are the same regions that control attention as well as impulse control in children without ADHD. Here are 10 theories, some more likely than others, that may help explain the brain changes that cause ADHD symptoms:
1. Genetics. ADHD symptoms tend to run in families. Studies show that one in four children with a diagnosis of ADHD will have a close family member with ADHD.
2. Lead Exposure. Studies have shown an association between lead exposure and ADHD symptoms in young children. Lead may enter a child’s drinking water from old plumbing fixtures. Children may also be exposed from lead paint. “These exposures are known to increase the risk of ADHD, but these exposures are becoming increasingly rare and most children with a diagnosis of ADHD have no evidence of significant lead exposure,” Hunter notes.
3. Cigarettes and Alcohol. Two toxins that have been shown to increase the risk of ADHD in children are cigarette smoke and alcohol. Smoking and drinking during pregnancy are associated with a number of serious health risks for both mother and fetus. Not surprisingly, several studies have specifically linked these substances to an increased risk of having a child with ADHD.