Autism is a disorder of neural developmentcharacterized by impaired social interaction and communication,and by restricted and repetitive behavior. These signs all begin before a childis three years old. Autism affects information processing in the brainby altering how nerve cells and their synapses connectand organize; how this occurs is not well understood. The two other autismspectrum disorders (ASD) are Aspergersyndrome, which lacks delays in cognitive development and language, and PDD-NOS,diagnosed when full criteria for the other two disorders are not met.
Autism has a strong genetic basis, although the genetics of autism are complex and it isunclear whether ASD is explained more by rare mutations, orby rare combinations of common genetic variants. In rare cases, autism isstrongly associated with agents that cause birth defects. And environmental causes,such as heavy metals, pesticides orchildhood vaccines
Parents usually notice signs in the first two years of their child's life.The signs usually develop gradually, but some autistic children first developmore normally and then regress. Although early behavioral or cognitiveintervention can help autistic children gain self-care, social, andcommunication skills, there is no known cure. Not many children with autismlive independently after reaching adulthood, though some become successful.
Autism is a highly variable neurodevelopmental disorder that firstappears during infancy or childhood, and generally follows a steady coursewithout remission. Overt symptoms gradually beginafter the age of six months, become established by age two or three years, andtend to continue through adulthood, although often in more muted form. It isdistinguished not by a single symptom, but by a characteristic triad ofsymptoms: impairments in social interaction; impairments in communication; andrestricted interests and repetitive behavior. Other aspects, such as atypicaleating, are also common but are not essential for diagnosis. Autism'sindividual symptoms occur in the general population and appear not to associatehighly, without a sharp line separating pathologically severe from commontraits.
Social deficits distinguish autism and the related autism spectrum disorders from otherdevelopmental disorders. People with autism have social impairments and oftenlack the intuition about others that many people take for granted. Unusualsocial development becomes apparent early in childhood. Autistic infants showless attention to social stimuli, smile and look at others less often, andrespond less to their own name. Autistic toddlers differ more strikingly from socialnorms; for example, they have less eye contactand turn taking, and are more likely to communicate by manipulating anotherperson's hand. Three- to five-year-old autistic children are less likely toexhibit social understanding, approach others spontaneously, imitate andrespond to emotions, communicate nonverbally, and take turns with others.However, they do form attachments to their primary caregivers.Most autistic children display moderately less attachment security than non-autisticchildren, although this difference disappears in children with higher mentaldevelopment or less severe ASD. Older children and adults with ASD performworse on tests of face and emotion recognition.
Contrary to common beliefs, autistic children do not prefer being alone.Making and maintaining friendships often proves to be difficult for those withautism. For them, the quality of friendships, not the number of friends,predicts how lonely they feel. Functional friendships, such as those resultingin invitations to parties, may affect the quality of life more deeply.
About a third to a half of individuals with autism doesn’t develop enoughnatural speech to meet their daily communication needs.Differences in communication may be present from the first year of life, andmay include delayed onset of babbling, unusual gestures, diminished responsiveness, andvocal patterns that are not synchronized with the caregiver. In the second andthird years, autistic children have less frequent and less diverse babbling,consonants, words, and word combinations; their gestures are less oftenintegrated with words. Autistic children are less likely to make requests orshare experiences, and are more likely to simply repeat others' words (echolalia) orreversepronouns. Joint attention seems to be necessary forfunctional speech, and deficits in joint attention seem to distinguish infantswith ASD: for example, they may look at a pointing hand instead of thepointed-at object,and they consistently fail to point at objects in order to comment on or sharean experience. Autistic children may have difficulty with imaginative play andwith developing symbols into language.
In a pair of studies, high-functioning autistic children aged 8–15performed equally well as, and adults better than, individually matchedcontrols at basic language tasks involving vocabulary and spelling. Bothautistic groups performed worse than controls at complex language tasks such asfigurative language, comprehension and inference. As people are often sized upinitially from their basic language skills, these studies suggest that peoplespeaking to autistic individuals are more likely to overestimate what theiraudience comprehends.
Autistic individuals displaymany forms of repetitive or restricted behavior
Stereotypy is repetitive movement, such as handflapping, making sounds, head rolling, or body rocking.
- Compulsive behavior is intended and appears to follow rules, such as arranging objects in stacks or lines.
- Sameness is resistance to change; for example, insisting that the furniture not be moved or refusing to be interrupted.
- Ritualistic behavior involves an unvarying pattern of daily activities, such as an unchanging menu or a dressing ritual. This is closely associated with sameness and an independent validation has suggested combining the two factors.
- Restricted behavior is limited in focus, interest, or activity, such as preoccupation with a single television program, toy, or game.
- Self-injury includes movements that injure or can injure the person, such as eye poking, skin picking, hand biting, and head banging.
No single repetitive behavior seems to be specific to autism, but onlyautism appears to have an elevated pattern of occurrence and severity of thesebehaviors.