Yes. Response rate to treatment for SM is inversely proportional to age. In other words, when any kind of appropriate therapy is begun at an early age, response is much quicker and greater. In his treatment of children with selective mutism, Thompson (2000) found that children who establish speaking in previously mute settings before age eight typically become verbal in school and other social settings within one year. The older a child is, the more he/she has become accustomed to the nonverbal behavior and the more difficult it is to change. This is why SMA advocates for early diagnosis and treatment.