Yes. It is true that younger children respond better, and the children who have fully recovered have all, to our knowledge, been under age 3. Older children and even adults have had remarkable improvements however. How much response you see will depend on many factors in addition to age. These include: current level of functioning, condition of the gut, immune function, and of course, the subtype of the disorder. We have heard from high-functioning adults with autism who describe going on the diet as "a fog lifting." Despite the fact that older children and adults have not been "cured," many have achieved functioning far beyond their caregivers' expectations.