The term “developmental disabilities” encompasses a wide range of physical and mental disabilities. According to the Centers for Disease Control and Prevention, parents report some sort of developmental disability in one of six children. Intellectual disability and autism spectrum disorder both are considered developmental disabilities.
About 2 percent of U.S. residents have intellectual disabilities, which impede their cognitive functioning and their ability to master life skills. People with intellectual disabilities may have difficulty with reading, writing, math, communication, social skills, or other activities of daily life. Intelligence Quotient (IQ) measurements are controversial because IQ scores have often pigeonholed people in ways that constrain their opportunities and curtail their education. Nevertheless, those scores are often used in diagnosing intellectual disabilities. Scores of 50-70 are often termed mild intellectual disability. Most students who qualify for college programs for people with intellectual disabilities generally have IQ scores ranging from 50-75. A thorough introduction to intellectual disabilities is available at parentcenterhub.org/intellectual. Families looking for college programs for students with intellectual disabilities can find a detailed list of programs and other resources at thinkcollege.net.
About two of 100 people, more often males than females, have autism spectrum disorder. It affects how people understand and socialize with others, often causing difficulty in interacting and communicating. Many people on the autism spectrum have average or high IQ scores; about a third of people with intellectual disabilities also have autism spectrum disorder. To learn more about autism, cdc.gov/ncbddd/autism/facts.html is a good start. Families looking for college programs for students on the spectrum can find resources at collegeautismspectrum.com.
The causes of most developmental disabilities are unclear. Genetics, parental health and behavior, infection during pregnancy, exposure to harmful material (lead, for example) during pregnancy, and premature birth appear to contribute to many developmental disabilities. Three conditions with well-established causes are:
- Down syndrome occurs in people with an extra copy of a chromosome in their genetic code. Mild to moderate intellectual disability is common among people who have Down syndrome. It affects about one in 1,200 people in the United States. More information is available at down-syndrome.org.
- Mutations in a single gene cause Fragile X syndrome, which causes mild to moderate intellectual disability in most males and in about a third of females. The incidence of Fragile X is estimated at one in 2,500-4,000 males and one in 7,000-8,000 females. Much more about Fragile X is at fragilex.org.
- Maternal alcohol use causes Fetal Alcohol Spectrum Disorders, which can include intellectual disability. A recent CDC study found such disorders in three out of 10,000 children ages 7-9. Basic information about FASD is available at cdc.gov/ncbddd/fasd/. Much more about prevention and support can be found at www.nofas.org.