Researchers have discovered that up to a third of children diagnosed with Attention Deficit Disorder (ADHD) are linked to the mother smoking during pregnancy or lead exposure during childhood. The researchers found no link between exposure to second-hand smoke after birth and ADHD.
Information on 4,704 children, aged 4-15, was examined by the researchers. This total included 4.2% who suffered from ADHD. They found that a child whose mother smoked while he/she was in her womb is 2.5 times more likely to develop ADHD than a child whose mother had not smoked while she was pregnant.
They also found that children with high lead blood levels had a 4 times higher likelihood of having ADHD, when compared to children with normal lead blood levels.
The researchers did not establish a causative relationship between these two factors — lead exposure and prenatal smoking. Neither factor was shown to have caused ADHD in the children studied. Instead, both factors could only be linked to an increased likelihood in an ADHD diagnosis.
The results appeared in the September 19, 2006 issue of Environmental Health Perspectives.