80 Neurodevelopmental Disorders
ally resolves with age. Complex stereotypi es are less common in typically developing
children and can usually be suppressed by dist raction or sensory stimulation. The indi-
vidual’s daily routine is rarely affected, and the movements generally do not cause the
child distress. The diagno sis would not be appropriat e in these circumstances.
Autism spectrum disorder. Stereotypic movements may be a presenting symptom of
autism spectrum disorder and should be con sidered when repetitive movements and be-
haviors are being evaluated. Deficits of soci al communication and re ciprocity manifesting
in autism spectrum disorder are generally ab sent in stereotypic mo vement disorder, and
thus social interaction, social communication , and rigid repetitive behaviors and interests
are distinguishing features. Wh en autism spectrum disorder is present, stereotypic move-
ment disorder is diagnosed only when there is self-injury or when the stereotypic behav-
iors are sufficiently severe to  become a focus of treatment.
Tic disorders. Typically, stereotypies have an earlier age at onset (before 3 years) than
do tics, which have a mean age at onset of 5–7 years. They are consistent and fixed in their
pattern or topography compared with tics, which are variable in their presentation. Ste-
reotypies may involve arms, hands, or the entire body, while tics commonly involve eyes,
face, head, and shoulders. Stereotypies are more fixed, rhythmic, and prolonged in dura-
tion than tics, which, generally, are brief, ra pid, random, and fluctuating. Tics and stereo-
typic movements are both reduced by distraction.
Obsessive-compulsive and related disorders. Stereotypic movement disorder is dis-