Mental Retardation Defined In the Texas MHMR system, mental retardation is defined as a usually permanent condition originating sometime between birth and age 18.
Mental retardation is found among all races and cultures.
An estimated three percent of the population has mental retardation. Unlike mental illness, mental retardation always is associated with limited intellectual capacity, it occurs before age 18, and it is a permanent condition. In contrast, mental illness is not associated with a particular level of intelligence, it may occur in a person at any age, and it is often temporary and treatable. Like all other persons, individuals with mental retardation can become mentally ill and they can be treated for their mental illness. They can learn, adjust socially and benefit from appropriate education, training, personal care and opportunities to work.