Autism spectrum disorder (ASD) refers to a neurological and developmental disorder that begins in early childhood or infancy and continues throughout a person's lifespan. ASD affects behavior, communication, and learning. Early theorists blamed parents for ASD, attributing the disorder to cold and rejecting mothers. Although ASD does run in families, this is a consequence of genetics, not parenting style. In addition to genetic factors, exposure to toxins and prenatal infections also increase risk for the disorder.
Greater awareness and improved diagnostic techniques have led to an increase in diagnoses. Some people believe that childhood vaccines cause ASD. This idea originated with a 1998 research paper by Andrew Wakefield, a British medical doctor. This paper claimed to prove an association between vaccines and the disorder. Celebrities and talk show hosts began talking about the health risks of vaccines. However, the original paper was discredited due to unethical research practices and biased analyses. Many large-scale studies conducted around the world show that there is no credible link between vaccination and ASD. However, fears that vaccines increase risk for ASD has led to a decrease in vaccination rates in many industrialized nations. In turn, this has increased risk for outbreaks of preventable diseases, such as measles, which can negatively impact a child's brain development.
ASD presents as a wide and diverse range of behaviors and encompasses a spectrum of abilities and disabilities. Children with severe ASD do not speak or communicate well. They may have low intelligence and severe learning disabilities and exhibit highly ritualistic behavior. A small percentage of people with ASD demonstrate gifted abilities in a specialized area (for example, music, art, or math). These savants may exhibit feats of memory, complete complicated math calculations in their head, or produce remarkable works of art.
The DSM-5 categorizes ASD according to three levels of needed support. Level 3, "Requiring Very Substantial Support," applies to people with severe deficits in verbal and nonverbal communication. Repetitive behaviors for people in this category might include hand flapping, rocking, jumping, arranging and rearranging objects, and repeating sounds or words. The other two levels are Level 2, "Requiring Substantial Support," and Level 1, "Requiring Support." At these levels, marked deficits in verbal and nonverbal social communication skills decrease, and flexibility and coping with change improve in some circumstances.People with mild ASD do not have significant language delays and have average or above average intelligence. However, they are socially awkward, have trouble understanding social conventions, and seem to lack empathy. In previous versions of the DSM, mild autism was called Asperger syndrome.