What Are Intellectual Disabilities?

There are several types of intellectual disabilities, with the most common being mental retardation. Some types can be prevented, while others cannot.

Mental retardation, which the American Psychiatric Association (APA) is currently proposing be renamed as intellectual disability, is a label for impaired IQ and ability to function. Over time the stigma associated with this label has lessened, although it is far from gone. One of the reasons the APA is suggesting a name change is due to the negative connotation that mental retardation evokes. This is not the first time that the APA has changed the nomenclature for mental retardation. Feeble-minded, idiot, moron, and imbecile were all diagnostic labels for the condition.

According to the Department of Psychology at the University of Alabama:

"...the elements of the definition of mental retardation were well accepted in the United States by 1900. These included: onset in childhood, significant intellectual or cognitive limitations, and an inability to adapt to the demands of everyday life...Three levels of impairment were identified: idiot, individuals whose development is arrested at the level of a 2 year old; imbecile, individuals whose development is equivalent to that of a 2 to 7 year old at maturity; and moron, individuals whose mental development is equivalent to that of a 7 to 12 year old at maturity."

This system was later replaced with mild, moderate, severe and profound levels of retardation, since the other terms had developed such a negative connotation.

According to the Centers for Disease Control (CDC), Down syndrome is the condition when a baby is born with an extra chromosome. This extra copy of a chromosome changes the body's and brain's normal development and causes mental and physical difficulties. Down syndrome symptoms can range from mild to severe. In general, both mental development and physical development are slower for people with Down syndrome.

The CDC states that some common physical signs of Down syndrome are:

A flat face with an upward slant to the eye, a short neck, small ears, and a large tongue; small hands and feet; a single crease across the palm of the hand; small pinky fingers that sometimes curve toward the thumb; and poor muscle tone or loose ligaments.

The cause of Down syndrome isn't known, so there isn't a way to prevent it. One controversial method of avoiding Down syndrome is having a genetic test done while the mother is pregnant, then choosing to abort the fetus if the test is positive for Down syndrome.

Autism Spectrum Disorders mainly affect language and social skills. Some individuals with autism are also mentally retarded. According to the CDC the three types of autistic disorders are:

Autistic Disorder (also called "classic" autism)- This is what most people think of when hearing the word "autism." People with autistic disorder usually have significant language delays, social and communication challenges, and unusual behaviors and interests. Many people with autistic disorder also have an intellectual disability.

Asperger Syndrome- People with Asperger syndrome usually have some milder symptoms of autistic disorder. They might have social challenges and unusual behaviors and interests. However, they typically do not have problems with language or intellectual disability.

Pervasive Developmental Disorder - Not Otherwise Specified (PPD-NOS; also called "atypical autism")- People who meet some of the criteria for autistic disorder or Asperger syndrome, but not all, may be diagnosed with PDD-NOS. People with PDD-NOS usually have fewer and milder symptoms than those with autistic disorder. The symptoms might cause only social and communication challenges.

Autism affects 1 in 110 children in the United States. That is up from 1 in 150 children just a few years ago.

There is controversy over what, if any, environmental factors affect the likelihood of a child developing autism. Since there is no consensus on what is causing the increase in children affected, there is no way yet known to prevent autism.

Fetal alcohol spectrum disorders (FASD) is 100 percent preventable. If a mother does not consume alcohol while pregnant, her child cannot develop FAS.

The CDC states that FASD commonly cause: abnormal facial features, such as a smooth ridge between the nose and upper lip; small head size; shorter-than-average height; low body weight; poor coordination; hyperactive behavior; difficulty paying attention; poor memory; difficulty in school (especially with math); learning disabilities; speech and language delays; low IQ; poor reasoning and judgment skills; vision or hearing problems; and problems with the heart, kidneys, or bones.

According to the CDC, certain metabolic disorders, when left untreated, can also lead to the development of an intellectual disability. Proper diagnosis and treatment can prevent most of these cases of intellectual disabilities.

Some common metabolic disorders include: phenylketonuria (PKU), galactosemia, and congenital hypothyroidism.

According to the CDC, kernicterus condition is caused when a newborn's liver produces too much bilirubin. This is common in newborns and often resolves on its own, but when it doesn't the persistent jaundiced condition affects the child's brain development.

Intellectual Disabilities, http://cdc.gov/ncbddd/dd/mr3.htm
Mental Retardation, A Symptom and a Syndrome, http://www.uab.edu/cogdev/mentreta.htm
Down Syndrome, http://www.cdc.gov/ncbddd/birthdefects/DownSyndrome.htm
Autism Spectrum Disorders, http://www.cdc.gov/ncbddd/autism/index.html
Fetal Alcohol Syndrome, http://www.cdc.gov/ncbddd/fasd/facts.html