New research into the causes of attention-deficit hyperactivity disorder (ADHD) seem to suggest that lead exposure could be a contributing factor for up to 30% of ADHD children.
The findings from two new studies, published in this month’s issue of the journal Current Directions in Psychological Science, suggest that exposure to lead may be the second leading cause of ADHD, after genetics. Researchers said they found a consistent link between elevated lead levels and ADHD signs in children.
Scientists have been able to account for only about 70% of all ADHD cases through genetics, considered to be the primary cause. However, the cause of the other 30% of cases has been hard to determine.
The new studies found that children with ADHD had higher blood lead levels than those who do not show signs of the behavioral disorder. Researchers also found that the higher the blood lead levels, the more signs of ADHD were present in children’s behavior. High blood lead levels can also result in lead poisoning. The U.S. Centers for Disease Control and Prevention (CDC) consider 10 milligrams of lead per deciliter of blood to be the level of concern for lead exposure.
Blood lead levels traditionally considered to be lead poisoning can result in nervous system injury, brain damage, seizures or convulsions, growth or mental retardation, coma and even death. Most cases of elevated lead blood levels in children are caused by exposure to lead paint, which is still present in many older homes throughout the United States. If the paint flakes off the wall, young children could ingest the paint chips or breathe in the dust, causing elevated levels of lead in the blood.
These latest studies follow on the heels of research published in the last two months that has connected low levels of lead exposure to kidney damage in children, as well as depression and panic disorders in young adults.