This disorder has onset before the age of 18 and is manifested in significantly below average intellectual functioning and concurrent deficits in adaptive functioning in two or more of the following areas: communication, self-care, home living, social skills, use of community resources, self-direction, functional academic skills, work, leisure, health, and safety. Mental retardation is often described in terms of degree of impairment (mild, moderate, severe, or profound) or the types and intensities of supportive services needed (intermittent, limited, extensive, or pervasive).