Autism Spectrum Disorder 55
Criterion D requires that the features must ca use clinically significant impairment in so-
cial, occupational, or other impo rtant areas of current function ing. Criterion E specifies that
the social communication defici ts, although sometime s accompanied by intellectual disabil-
ity (intellectual developmental disorder), are not in line with the individual’s developmental
level; impairments exceed difficulties expected on the basis of developmental level.
Standardized behavioral diagnostic instruments with good psychometric properties,
including caregiver interviews, questionnair es and clinician observation measures, are
available and can improve re liability of diagnosis over time and across clinicians.
Associated Features Supporting Diagnosis
Many individuals with autism spectrum disorder also have intellectual impairment and/or
language impairment (e.g., slow  to talk, language comprehension behind production). Even
those with average or high inte lligence have an uneven profil e of abilities. The gap between
intellectual and adaptive function al skills is often large. Moto r deficits are often present, in-
cluding odd gait, clumsiness, and other abnormal  motor signs (e.g., walk ing on tiptoes). Self-
injury (e.g., head banging, biting the wris t) may occur, and disr uptive/challenging behav-
iors are more common in children and adoles cents with autism spectrum disorder than
other disorders, including intellectual disabili ty. Adolescents and adults with autism spec-
trum disorder are prone to anxiety and depres sion. Some individuals develop catatonic-like
motor behavior (slowing and “f reezing” mid-action), but thes e are typically not of the mag-
nitude of a catatonic episode. However, it is possible for individuals with autism spectrum
disorder to experience a marked deterioratio n in motor symptoms an d display a full cata-