individuals with intellectual disability, the ster eotyped, self-injurious behaviors may persist
for years, even though the typography or pattern of self-injury may change.
Risk and Prognostic Factors
Environmental. Social isolation is a risk factor for self-stimulation that may progress to
stereotypic movements with repetitive self-inj ury. Environmental stress may also trigger
stereotypic behavior. Fear may alter physiological state, resulting in increased frequency
of stereotypic behaviors.
Genetic and physiological. Lower cognitive functioning is link ed to greater risk for stereo-
typic behaviors and poorer response to interv entions. Stereotypic movements are more fre-
quent among individuals with moderate-to-se vere/profound intellectual disability, who by
virtue of a particular syndrome (e.g., Rett syndrome) or environmental factor (e.g., an environ-
ment with relatively insufficient stimulation) se em to be at higher risk for stereotypies. Repet-
itive self-injurious behavior ma y be a behavioral phenotype in  neurogenetic syndromes. For
example, in Lesch-Nyhan syndrome, there are bo th stereotypic dystonic  movements and self-
mutilation of fingers, lip biti ng, and other forms of self-injury unless the individual is re-
strained, and in Rett syndrome and Cornelia de  Lange syndrome, self-i njury may result from
the hand-to-mouth st ereotypies. Stereotypic behaviors may result from a painful medical con-
dition (e.g., middle ear infection, de ntal problems, gastro esophageal reflux).
Culture-Related Diagnostic Issues
Stereotypic movement disorder, wi th or without self-injury, occurs in all races and cultures.
Cultural attitudes toward unusual behaviors may result in delayed diagnosis. Overall cultural