Developmental disabilities are physical and mental conditions that arise before the age of 18 and that can contribute to lifelong difficulties for sufferers in the areas of independent living, employment, and relationships. The various types of developmental disabilities have a range of symptoms and can be genetic, physical, or psychological in nature. Common developmental disabilities include intellectual disabilities, neurological disabilities such as cerebral palsy, and sensory impairment such as vision or hearing disorders.
Intellectual disabilities, sometimes known as mental retardation, impair an individual's ability to acquire knowledge, develop skills, and reason. People with intellectual disabilities may find it difficult to communicate with others, perform basic daily living tasks, or make good decisions. An intellectual disability can have any number of causes, such as a chromosomal disorder like Down Syndrome, or may be the result of prenatal damage, such as fetal alcohol syndrome or brain damage at birth or later in life due to an accident. Intellectual disabilities are typically diagnosed by administering an intelligence test, sometimes called an intelligence quotient (IQ) test, to the person suspected of being intellectually disabled. A low score on such a test can indicate the presence of an intellectual disability.
Autistic spectrum disorders are another type of developmental disability. Individuals on the autism spectrum have difficulties with communication and social interaction and may demonstrate a strong attachment to routines and rituals and engage in repetitive behaviors. Autism symptoms vary considerably, with some on the spectrum demonstrating significant impairment, while others attend regular schools, hold gainful employment, and may even marry and raise a family. Among developmental disabilities, autism spectrum disorders are some of the most diverse when it comes to the functioning of those diagnosed as on the spectrum. For this reason, autism spectrum disorders can be more difficult to diagnose than other types of developmental disabilities, as much of the diagnostic process is based on the observations of parents, teachers, and mental health professionals rather than more objective forms of testing.
Vision and hearing impairments are developmental disabilities that may not in and of themselves cause cognitive impairments. They can, however, limit how a child learns and interacts with the world. If no intervention takes place, a child may be delayed in his or her intellectual, social, and emotional development. For this reason, parents are encouraged to report any suspected vision or hearing impairments to their pediatrician so that further testing can be done.