Children with lead poisoning could show problems with concentration, behavior, and schoolwork. Lead could be found in houses, toys, or furniture painted made before 1976 or 1978, as well as in plumbing.
Like kids with ADHD, children with autism might not adjust to change very well, and high-stimulus environments might cause them to get overly excited, which can seem like the hyperactivity associated with ADHD. Both kids with autism and those with ADHD can have a hard time bonding emotionally and understanding social rules, making it tough for them to fit in and make friends. But kids with autism will have more difficulties communicating than a child with ADHD would because they find it hard to decipher nonverbal language like tone of voice, facial expressions, and body language. Read more about the differences between ADHD and autism here.