ADHD has an estimated prevalence of 8.7% among children, though estimates vary. It is more common in boys than girls, and symptoms may reduce as individuals age. ADHD can cause impairment in domains like peer and adult relationships, academic progress, self-esteem, and group functioning. While the exact causes of ADHD are unknown, it is not caused by factors like parenting, diet, or technology overuse, but is likely due to a combination of genetics and environment.