First, The National Dissemination Center for Children with Disabilities defined intellectual disability as being a person that has certain limitations in mental functioning and in skills such as communicating, taking care of one’s self, and social skills. Also, all of these limitations and more cause a person to learn and develop slower than any typical child. Autism is defined as a mental condition, present from early childhood, characterized by great difficulty in communicating and forming relationships. It also is a condition where the fantasy dominates over reality, as a symptom of schizophrenia and other disorders. The cause of autism is unknown or idiopathic. Most people believe that genetic disorders or exposures to toxins cause autism or show some autism-like symptoms though. Severe disabilities are defined as people who traditionally have been labeled as having severe profound mental retardation. Multiple disabilities are defined as and basically are concomitant impairments such as mental retardation-blindness, mental retardation-orthopedic impairment or a combination of the two. The cause of severe disabilities and multiple disabilities are undefined even though more than half of the children are born this way. In some known cases it is said that these disabilities occur from chromosomal abnormalities, developmental disorders of the brain, metabolic disorders, and negative prenatal environmental influences such as drinking, taking drugs that are not prescribed or safe for the baby or even getting hit or pushed on your stomach to where you have to deliver your child prematurely can also cause disabilities. Intellectual disability can be caused by any condition that impairs the development of the brain before birth, during birth or in the childhood years.
References: Celebi, J. (2011). Top 20 Winning Quotes for Parents of Children with Special Needs - Overwhelmed No More! BLOG - SpecialNeedsParentCoach.com. Home - SpecialNeedsParentCoach.com. Retrieved January 12, 2013, from http://www.specialneedsparentcoach.com/blog/2009/7/30/top-20-winning-quotes-for-parents-of-children-with-special-n.html Hardman, M.L., Drew, C.J., & Eagan, M.W. (2009). Human exceptionality: Society, School and Family. Allyn and Bacon Intellectual Disability — National Dissemination Center for Children with Disabilities. (2011, January). National Dissemination Center for Children with Disabilities —. Retrieved January 12, 2013, from http://nichcy.org/disability/specific/intellectual Westling, D.L. & Fox, L. (2008). Teaching Students with Severe Disabilities. Pearson What is Special Education? (2009, August). Garland Independent School District. Retrieved January 12, 2013, from http://www.garlandisd.net/departments/special_education/documents/What%20is%20SPED.pdf