Childhood disintegrative psychosis, a pervasive developmental disorder of childhood, is relatively rare and used to be called infantile dementia and HELLER syndrome. In such children, development is usually normal until the age of 3-4 years, and then there is a significant regression, for example, the originally acquired abilities (language skills, social skills) can quickly disappear within 1 year. At the beginning of the disease, there can be obvious symptoms of anxiety and irritability, then the ability disappears, and intelligence quickly drops to the level of moderate or severe mental retardation, that is, IQ level <50, and many affected children die prematurely as a result, and even if they can grow up, they need family members to live and take care of them. The cause remains unclear, and there are no specific neurological signs, and it is more common in boys.