More awareness. There's more awareness & acceptance of this diagnosis. It's always been with us, ~5% of the us population, but it went undignosed in children for too long. There is no evidence that anything other than inheritance & neurotrauma (prenatal nicotine, alcohol, mj, Cocaine exposure; prematurity, inflammation, perinatal stress, multiple births, oxygen deprivation, or intrauterine malnutrition)are cause.
Adhd. I personally think that there is something environmental affecting brain neurochemistry at young ages. Is it milk? Vaccines? Microwaves? Tv?