Table 1 Severity levels for
intellectual disability (intellectual developmental disorder)
|Severity level||Conceptual domain||Social domain||Practical domain|
children, there may be no obvious conceptual differences. For school-age children
and adults, there are difficulties in learning academic skills involving
reading, writing, arithmetic, time, or money, with support needed in
one or more areas to meet age-related expectations. In adults, abstract
thinking, executive function (i.e., planning, strategizing, priority
setting, and cognitive flexibility), and short-term memory, as well
as functional use of academic skills (e.g., reading, money management),
are impaired. There is a somewhat concrete approach to problems
and solutions compared with age-mates.
typically developing age-mates, the individual is immature in social interactions.
For example, there may be difficulty in accurately perceiving peers’
social cues. Communication, conversation, and language are more
concrete or immature than expected for age. There may be difficulties
regulating emotion and behavior in age-appropriate fashion; these
difficulties are noticed by peers in social situations. There is
limited understanding of risk in social situations; social judgment
is immature for age, and the person is at
risk of being manipulated by others (gullibility).
The individual may function
age-appropriately in personal care. Individuals need some support
with complex daily living tasks in comparison to peers. In adulthood,
supports typically involve grocery shopping, transportation, home
and child-care organizing, nutritious food preparation, and banking
and money management. Recreational skills resemble those of age-mates,
although judgment related to well-being and organization around
recreation requires support. In adulthood, competitive employment
is often seen in jobs that do not emphasize conceptual skills. Individuals
generally need support to make health care decisions and legal decisions,
and to learn to perform a skilled vocation competently. Support
is typically needed to raise a family.
development, the individual’s conceptual skills lag markedly behind
those of peers. For preschoolers, language and pre-academic skills develop
slowly. For school-age children, progress in reading, writing, mathematics,
and understanding of time and money occurs slowly across the school
years and is markedly limited compared with that of peers. For adults,
academic skill development is typically at an elementary level,
and support is required for all use of academic skills in work and
personal life. Ongoing assistance on a daily basis is needed to
complete conceptual tasks of day-to-day life, and others may take
over these responsibilities fully for the individual.
shows marked differences from peers in social and communicative
behavior across development. Spoken language is typically a primary
tool for social communication but is much less complex than that
of peers. Capacity for relationships is evident in ties to family
and friends, and the individual may have successful friendships
across life and sometimes romantic relations in adulthood. However,
individuals may not perceive or interpret social cues accurately.
Social judgment and decision-making abilities are limited, and caretakers
must assist the person with life decisions. Friendships with typically developing
peers are often affected by communication or social limitations.
Significant social and communicative support is needed in work settings
The individual can care
for personal needs involving eating, dressing, elimination, and
hygiene as an adult, although an extended period of teaching and time
is needed for the individual to become independent in these areas,
and reminders may be needed. Similarly, participation in all household
tasks can be achieved by adulthood, although an extended period
of teaching is needed, and ongoing supports will typically occur
for adult-level performance. Independent employment in jobs that
require limited conceptual and communication skills can be achieved,
but considerable support from co-workers, supervisors, and others
is needed to manage social expectations, job complexities, and ancillary responsibilities
such as scheduling, transportation, health benefits, and money management.
A variety of recreational skills can be developed. These typically
require additional supports and learning opportunities over an extended
period of time. Maladaptive behavior is present in a significant minority
and causes social problems.
of conceptual skills is limited. The individual generally has little
understanding of written language or of concepts involving numbers, quantity,
time, and money. Caretakers provide extensive supports for problem
solving throughout life.
is quite limited in terms of vocabulary and grammar. Speech may
be single words or phrases and may be supplemented through augmentative
means. Speech and communication are focused on the here and now
within everyday events. Language is used for social communication
more than for explication. Individuals understand simple speech
and gestural communication. Relationships with family members and
familiar others are a source of pleasure and help.
The individual requires
support for all activities of daily living, including meals, dressing,
bathing, and elimination. The individual requires supervision at all
times. The individual cannot make responsible decisions regarding well-being
of self or others. In adulthood, participation in tasks at home,
recreation, and work requires ongoing support and assistance. Skill
acquisition in all domains involves long-term teaching and ongoing
support. Maladaptive behavior, including self-injury, is present
in a significant minority.
Conceptual skills generally involve
the physical world rather than symbolic processes. The individual
may use objects in goal-directed fashion for self-care, work, and
recreation. Certain visuospatial skills, such as matching and sorting
based on physical characteristics, may be acquired. However, co-occurring
motor and sensory impairments may prevent functional use of objects.
The individual has very
limited understanding of symbolic communication in speech or gesture.
He or she may understand some simple instructions or gestures. The
individual expresses his or her own desires and emotions largely
through nonverbal, nonsymbolic communication. The individual enjoys
relationships with well-known family members, caretakers, and familiar
others, and initiates and responds to social interactions through gestural
and emotional cues. Co-occurring sensory and physical impairments
may prevent many social activities.
The individual is dependent on others
for all aspects of daily physical care, health, and safety, although
he or she may be able to participate in some of these activities
as well. Individuals without severe physical impairments may assist
with some daily work tasks at home, like carrying dishes to the
table. Simple actions with objects may be the basis of participation
in some vocational activities with high levels of ongoing support.
Recreational activities may involve, for example, enjoyment in listening
to music, watching movies, going out for walks, or participating
in water activities, all with the support of others. Co-occurring
physical and sensory impairments are frequent barriers to participation
(beyond watching) in home, recreational, and vocational activities.
Maladaptive behavior is present in a significant minority.