Autism is a neurodevelopmental disorder characterized by impaired social interaction, verbal and non-verbal communication, and restricted and repetitive behavior. Parents usually notice signs in the first two years of their child's life. These signs often develop gradually, though some children with autism reach their developmental milestones at a normal pace and then regress. The diagnostic criteria require that symptoms become apparent in early childhood, typically before age three.
While autism is highly heritable, researchers suspect both environmental and genetic factors as causes. Autism affects information processing in the brain by altering how nerve cells and their synapses connect and organize; how this occurs is not well understood. It is one of three recognized Autism Spectrum Disorders (ASDs), the other two being Asperger syndrome and pervasive developmental disorder not otherwise specified, which is diagnosed when the full set of criteria for autism or Asperger syndrome are not met.
Early speech or behavioral interventions can help children with autism gain self-care, social, and communication skills. Although there is no known cure, there have been reported cases of children who recovered. Not many children with autism live independently after reaching adulthood, though some become successful. An autistic culture has developed, with some individuals seeking a cure and others believing autism should be accepted as a difference and not treated as a disorder.
Autism on Supernanny
Tristin from the Facente Family was diagnosed with Autism.
Autism first appears during infancy or childhood, and generally follows a steady course without remission. People with autism may be severely impaired in some respects but normal, or even superior, in others. Overt symptoms gradually begin after the age of six months, become established by age two or three years, and tend to continue through adulthood, although often in more muted form. It is distinguished by a characteristic triad of symptoms: impairments in social interaction; impairments in communication; and restricted interests and repetitive behavior.
Social deficits distinguish autism and the related autism spectrum disorders from other developmental disorders. People with autism have social impairments and often lack the intuition about others that many people take for granted.
Unusual social development becomes apparent early in childhood. Autistic infants show less attention to social stimuli, smile and look at others less often, and respond less to their own name. Autistic toddlers differ more strikingly; for example, they have less eye contact and turn-taking, and do not have the ability to use simple movements to express themselves, such as pointing at things. Three- to five-year-old children with autism are less likely to exhibit social understanding, approach others spontaneously, imitate and respond to emotions, communicate nonverbally, and take turns with others. However, they do form attachments to their primary caregivers.
Children with high-functioning autism suffer from more intense and frequent loneliness compared to non-autistic peers, despite the common belief that children with autism prefer to be alone. Making and maintaining friendships often proves to be difficult for those with autism. For them, the quality of friendships, not the number of friends, predicts how lonely they feel. Functional friendships, such as those resulting in invitations to parties, may affect the quality of life more deeply.
There are many anecdotal reports, but few systematic studies, of aggression and violence in individuals with ASD. The limited data suggest that, in children with intellectual disability, autism is associated with aggression, destruction of property, and tantrums.
About a third to a half of individuals with autism do not develop enough natural speech to meet their daily communication needs. Differences in communication may be present from the first year of life, and may include delayed onset of babbling, unusual gestures, diminished responsiveness, and vocal patterns that are not synchronized with the caregiver. In the second and third years, children with autism have less frequent and less diverse babbling, consonants, words, and word combinations; their gestures are less often integrated with words. Children with autism are less likely to make requests or share experiences, and are more likely to simply repeat others' words (echolalia) or reverse pronouns. Joint attention seems to be necessary for functional speech, and deficits in joint attention seem to distinguish infants with ASD: for example, they may look at a pointing hand instead of the pointed-at object, and they consistently fail to point at objects in order to comment on or share an experience. Children with autism may have difficulty with imaginative play and with developing symbols into language.
Autistic individuals display many forms of repetitive or restricted behavior, which the Repetitive Behavior Scale-Revised (RBS-R) categorizes as follows.
- Stereotypy is repetitive movement, such as hand flapping, 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.
- 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 or self-injurious behavior seems to be specific to autism, but autism appears to have an elevated pattern of occurrence and severity of these behaviors.
An estimated 0.5% to 10% of individuals with ASD show unusual abilities, ranging from splinter skills such as the memorization of trivia to the extraordinarily rare talents of prodigious autistic savants. Many individuals with ASD show superior skills in perception and attention, relative to the general population. Sensory abnormalities are found in over 90% of those with autism, such as under-responsivity (for example, walking into things), over-responsivity (for example, distress from loud noises) and sensation seeking (for example, rhythmic movements).
An estimated 60%–80% of autistic people have motor signs that include poor muscle tone, poor motor planning, and toe walking; deficits in motor coordination are pervasive across ASD and are greater in autism proper.
Unusual eating behavior occurs in about three-quarters of children with ASD. Selectivity is the most common problem, although eating rituals and food refusal also occur; this does not appear to result in malnutrition.
Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by rare mutations with major effects, or by rare multigene interactions of common genetic variants. Many genes have been associated with autism through sequencing the genomes of affected individuals and their parents.
Several lines of evidence point to synaptic dysfunction as a cause of autism.
All known teratogens (agents that cause birth defects) related to the risk of autism appear to act during the first eight weeks from conception, and though this does not exclude the possibility that autism can be initiated or affected later, there is strong evidence that autism arises very early in development.
Exposure to air pollution during pregnancy, especially heavy metals and particulates, may increase the risk of autism.
How autism occurs is not well understood. Its mechanism can be divided into two areas: the pathophysiology of brain structures and processes associated with autism, and the neuropsychological linkages between brain structures and behaviors.
It is not known whether autism is a few disorders caused by mutations converging on a few common molecular pathways, or is (like intellectual disability) a large set of disorders with diverse mechanisms. Autism appears to result from developmental factors that affect many or all functional brain systems, and to disturb the timing of brain development more than the final product. Neuroanatomical studies and the associations with teratogens strongly suggest that autism's mechanism includes alteration of brain development soon after conception.
Just after birth, the brains of children with autism tend to grow faster than usual, followed by normal or relatively slower growth in childhood. It seems to be most prominent in brain areas underlying the development of higher cognitive specialization.
The immune system is thought to play an important role in autism. Interactions between the immune system and the nervous system begin early during the embryonic stage of life, and successful neurodevelopment depends on a balanced immune response. It is thought that activation of a pregnant mother's immune system such as from environmental toxicants or infection can contribute to causing autism through causing a disruption of brain development. This is supported by recent studies that have found that infection during pregnancy is associated with an increased risk of autism.
The relationship of neurochemicals to autism is not well understood; several have been investigated, with the most evidence for the role of serotonin and of genetic differences in its transport. Some data suggests neuronal overgrowth potentially related to an increase in several growth hormones or to impaired regulation of growth factor receptors. Also, some inborn errors of metabolism are associated with autism, but probably account for less than 5% of cases.
The underconnectivity theory of autism hypothesizes that autism is marked by underfunctioning high-level neural connections and synchronization, along with an excess of low-level processes. Evidence for this theory has been found in functional neuroimaging studies on autistic individuals and by a brainwave study that suggested that adults with ASD have local overconnectivity in the cortex and weak functional connections between the frontal lobe and the rest of the cortex. Other evidence suggests the underconnectivity is mainly within each hemisphere of the cortex and that autism is a disorder of the association cortex.
Functional connectivity studies have found both hypo- and hyper-connectivity in brains of people with autism. Hypo-connectivity seems to dominate, especially for interhemispheric and cortico-cortical functional connectivity.
Two major categories of cognitive theories have been proposed about the links between autistic brains and behavior.
The first category focuses on deficits in social cognition.
- Simon Baron-Cohen's empathizing–systemizing theory postulates that autistic individuals can systemize—that is, they can develop internal rules of operation to handle events inside the brain—but are less effective at empathizing by handling events generated by other agents.
- An extension, the extreme male brain theory, hypothesizes that autism is an extreme case of the male brain, defined psychometrically as individuals in whom systemizing is better than empathizing.
The second category focuses on nonsocial or general processing: the executive functions such as working memory, planning, inhibition.
- In his review, Kenworthy states that "it is clear that executive dysfunction plays a role in the social and cognitive deficits observed in individuals with autism." Tests of core executive processes such as eye movement tasks indicate improvement from late childhood to adolescence, but performance never reaches typical adult levels.
- Weak central coherence theory hypothesizes that a limited ability to see the big picture underlies the central disturbance in autism. A related theory—enhanced perceptual functioning—focuses more on the superiority of locally oriented and perceptual operations in autistic individuals. These theories map well from the underconnectivity theory of autism.
Neither category is satisfactory on its own; social cognition theories poorly address autism's rigid and repetitive behaviors, while the nonsocial theories have difficulty explaining social impairment and communication difficulties. A combined theory based on multiple deficits may prove to be more useful.
Diagnosis is based on behavior, not cause or mechanism. Autism is characterized by persistent deficits in social communication and interaction across multiple contexts, as well as restricted, repetitive patterns of behavior, interests, or activities. These deficits are present in early childhood, typically before age three, and lead to clinically significant functional impairment. Sample symptoms include lack of social or emotional reciprocity, stereotyped and repetitive use of language or idiosyncratic language, and persistent preoccupation with unusual objects. The disturbance must not be better accounted for by Rett syndrome, intellectual disability or global developmental delay.
ASD can sometimes be diagnosed by age 14 months, although diagnosis becomes increasingly stable over the first three years of life: for example, a one-year-old who meets diagnostic criteria for ASD is less likely than a three-year-old to continue to do so a few years later.
Underdiagnosis and overdiagnosis are problems in marginal cases, and much of the recent increase in the number of reported ASD cases is likely due to changes in diagnostic practices.
Autism is one of the five pervasive developmental disorders (PDD), which are characterized by widespread abnormalities of social interactions and communication, and severely restricted interests and highly repetitive behavior.These symptoms do not imply sickness, fragility, or emotional disturbance.
The manifestations of autism cover a wide spectrum, ranging from individuals with severe impairments—who may be silent, developmentally disabled, and locked into hand flapping and rocking—to high functioning individuals who may have active but distinctly odd social approaches, narrowly focused interests, and verbose, pedantic communication.
Research into causes has been hampered by the inability to identify biologically meaningful subgroups within the autistic population and by the traditional boundaries between the disciplines of psychiatry, psychology, neurology and pediatrics.
About half of parents of children with ASD notice their child's unusual behaviors by age 18 months, and about four-fifths notice by age 24 months. According to an article in the Journal of Autism and Developmental Disorders, failure to meet any of the following milestones "is an absolute indication to proceed with further evaluations. Delay in referral for such testing may delay early diagnosis and treatment and affect the long-term outcome".
- No babbling by 12 months.
- No gesturing (pointing, waving, etc.) by 12 months.
- No single words by 16 months.
- No two-word (spontaneous, not just echolalic) phrases by 24 months.
- Any loss of any language or social skills, at any age.
US practice is to screen all children for ASD at 18 and 24 months, using autism-specific formal screening tests. In contrast, in the UK, children whose families or doctors recognize possible signs of autism are screened. It is not known which approach is more effective.
The main goals when treating children with autism are to lessen associated deficits and family distress, and to increase quality of life and functional independence. In general, higher IQs are correlated with greater responsiveness to treatment and improved treatment outcomes. No single treatment is best and treatment is typically tailored to the child's needs.
- Families and the educational system are the main resources for treatment.
- Intensive, sustained special education programs and behavior therapy early in life can help children acquire self-care, social, and job skills, and often improve functioning and decrease symptom severity and maladaptive behaviors. Available approaches include applied behavior analysis (ABA), developmental models, structured teaching, speech and language therapy, social skills therapy, and occupational therapy. Among these approaches, interventions either treat autistic features comprehensively, or focalize treatment on a specific area of deficit.
- There is some evidence that early intensive behavioral intervention (EIBI), an early intervention model based on ABA for 20 to 40 hours a week for multiple years, is an effective treatment for some children with ASD. Two theoretical frameworks outlined for early childhood intervention include applied behavioral analysis (ABA) and developmental social pragmatic models (DSP). One interventional strategy utilizes a parent training model, which teaches parents how to implement various ABA and DSP techniques. Despite the recent development of parent training models, these interventions have demonstrated effectiveness in numerous studies.
Many medications are used to treat ASD symptoms that interfere with integrating a child into home or school when behavioral treatment fails. More than half of US children diagnosed with ASD are prescribed psychoactive drugs or anticonvulsants, with the most common drug classes being antidepressants, stimulants, and antipsychotics.
- Antipsychotics, such as risperidone and aripiprazole, have been found to be useful for treating irritability, repetitive behavior, and sleeplessness that often occurs with autism, however their side effects must be weighed against their potential benefits, and
people with autism may respond atypically.
- No known medication relieves autism's core symptoms of social and communication impairments.
Although many alternative therapies and interventions are available, few are supported by scientific studies.
There is no known cure. Children recover occasionally, so that they lose their diagnosis of ASD; this occurs sometimes after intensive treatment and sometimes not. It is not known how often recovery happens; reported rates in unselected samples of children with ASD have ranged from 3% to 25%. Most children with autism acquire language by age five or younger, though a few have developed communication skills in later years. Most children with autism lack social support, meaningful relationships, future employment opportunities or self-determination. Although core difficulties tend to persist, symptoms often become less severe with age.
Few high-quality studies address long-term prognosis. Acquiring language before age six, having an IQ above 50, and having a marketable skill all predict better outcomes; independent living is unlikely with severe autism.