38 Neurodevelopmental Disorders
factors (e.g., sensory impairme nt, severe problem behavior), the individual may be diag-
nosed with unspecified intellectual disability.  Adaptive functioning may be difficult to
assess in a controlled setting (e.g., prisons, dete ntion centers); if poss ible, corrob orative in-
formation reflecting functioning outsid e those settings should be obtained.
Criterion B is met when at least one domain  of adaptive functioning—conceptual, so-
cial, or practical—is sufficiently impaired th at ongoing support is needed in order for the
person to perform adequately in one or more life settings at school, at work, at home, or in
the community. To meet diagnostic criteria for intellectual disability, the deficits in adap-
tive functioning must be directly related to  the intellectual impairments described in Cri-
terion A. Criterion C, onset during the deve lopmental period, refers to recognition that
intellectual and adaptive deficits are pr esent during childhood or adolescence.
Associated Features Supporting Diagnosis
Intellectual disability is a heterogeneous condition with multiple causes. There may be
associated difficulties with social judgment; assessment of risk; self-management of behav-
ior, emotions, or interpersonal relationships; or  motivation in school or work environments.
Lack of communication skills may predispose to disruptive and aggressive behaviors. Gull-
ibility is often a feature, involving naiveté in social situations and a tendency for being easily
led by others. Gullibility and lack of awareness of  risk may result in exploitation by others
and possible victimization, fraud, unintentional criminal involvement, false confessions,
and risk for physical and sexual abuse. These associated features can be important in crim-
inal cases, including Atkins-type hearings involving the death penalty.
Individuals with a diagnosis of intellectual disability with co-occurring mental disor-