 In addition to genetics , some environmental factors might play a role . Alcohol intake during pregnancy can cause fetal alcohol spectrum disorders which can include ADHD or symptoms like it . Children exposed to certain toxic substances , such as lead or polychlorinated biphenyls , may develop problems which resemble ADHD . Exposure to the organophosphate insecticides chlorpyrifos and <unk> phosphate is associated with an increased risk ; however , the evidence is not conclusive . Exposure to tobacco smoke during pregnancy can cause problems with central nervous system development and can increase the risk of ADHD . 
