Environmental factors of ADHD

In utero complications can lead to a variety of neurodevelopmental complications.

Twin studies suggest 9% to 20% ADHD symptoms may be due to nonshared environmental (nongenetic) factors.

Environmental factors implicated include in utero exposure to alcohol, maternal smoking and environmental exposure to lead in very early life.The relation of maternal smoking to ADHD could be due to nicotine causing Intrauterine hypoxia. It could also be that women with ADHD are more likely to smoke and therefore, due to the strong genetic component of ADHD, are more likely to have children with ADHD. Complications during pregnancy and birth—including premature birth—might also play a role. ADHD patients have been observed to have higher than average rates of head injuries; however, current evidence does not indicate that head injuries are the cause of ADHD in the patients observed. Infections during pregnancy, at birth, and in early childhood are linked to an increased risk of developing ADHD. These include various viruses (measles, varicella, rubella, enterovirus 71) and streptococcal bacterial infection.

dikutip dari : http://en.wikipedia.org/wiki/Attention-deficit_hyperactivity_disorder