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Background to Autism

Description:
Autism is a disorder in brain development that becomes apparent in earliest childhood. It is defined by problems in socialization, communication, and repetitive behaviors.
Transcript:
Autism is a disorder in brain development that becomes apparent in earliest childhood. It is defined by problems in three areas: * severe impairments in how children relate to other people * delays or abnormalities in how they communicate * restrictive, odd, and repeated (stereotyped) behavior Autism is the best known of the pervasive developmental disorders (PDDs). Others include childhood disintegrative disorder (CDD) and pervasive developmental disorder not otherwise specified (PDD-NOS), covering individuals whose impairments do not meet all the clinical criteria for autism (because of when the impairments developed or what behaviors emerged). The treatments and prognoses for these conditions are the same as for autism, and because people show a wide range of functioning within each, we consider them all to be within an “autistic spectrum” in this book. Also among PDDs are Asperger’s syndrome and Rett’s disorder, discussed in the sections that follow. PDDs are much less rare than we once thought. It is reasonably certain that at least 20 of every 10,000 individuals have such a disorder. About one fourth of these cases meet the criteria for autism, with about an equal number of cases of Asperger’s and PDD-NOS. Rett’s disorder is much rarer. The ratio of males to females with all PDDs is more than 3 to 1, except for Rett’s disorder, which only girls develop. Manifestations of Autism Autistic individuals differ greatly in the type and severity of symptoms they may exhibit. At least two subgroups in the range of autism appear to exist, defined by their degree of intellectual and social impairment: high functioning and low functioning. Many people with autism make considerable progress in various life skills, though most retain clear and disabling limitations. Social Behavior Some parents recall their child in infancy showing unusual social behaviors: being content to lie in the crib staring at inanimate objects, crying less than usual, not seeming to crave being held or cuddled. Often, they also report that an infant makes little or no eye contact, does not imitate gestures or facial expressions, and does not “coo” back and forth with adults as most babies do. Other autistic infants are remembered as colicky and irritable, and crying inconsolably, yet resistant to being held and comforted. However, many parents do not notice anything unusual until their child reaches age 2 without responding to spoken language. From the age of about eight months to three years, autistic children display other social deficits not seen in children developing normally. Autistic toddlers generally fail to use eye contact to check for parents’ approval or attention. Instead of pointing to an appealing object (a complex, coordinated act that involves making eye contact and guiding the caretaker’s gaze), they may take someone’s hand and attempt to use it as a tool to grasp the desired thing. Autistic children’s social skills and behavior lag well behind other children’s, but they often do progress as they grow older. A 2- or 3-year-old autistic child might consistently treat a parent like any adult stranger. A school-age autistic child, in contrast, might selectively prefer being with his or her parent but remain isolated from peers at school. An autistic early adolescent might wish to relate to peers but not know how. At one extreme among children with autism, a low-functioning 8-year-old might appear completely detached, avoid closeness with others, and seem totally absorbed by a few inanimate objects. At the opposite extreme, another 8-year-old autistic child might show active interest in other children at a playground but express this interest in odd ways—for example, by running around at a distance from the group. General Intelligence The range of general intelligence within the autistic population is wide. Approximately 70 percent to 80 percent have IQs consistent with mental retardation. These children show the fewest developmental gains as they age. About 20 percent of autistic individuals have average or superior intelligence. They are most likely to speak by age 6 and eventually attain language skills. Some autistic individuals appear cognitively deficient in some areas, yet may be remarkably superior in others. Such “savants” may display advanced skills in reading (hyperlexia), mathematics and counting, memory, art, and music, or acquire incredible knowledge in restricted areas. Thus, some children with autism have islands of average or excellent intellectual ability (“splinter abilities”), yet cannot adapt this intelligence for general use. This implies that the crucial cognitive deficits in autism involve the brain’s executive functions. Language and Communication All young autistic children show some delay in language, as well as a lag in becoming aware of communication itself. Often parents suspect the problem is deafness, the most common fear that first brings families with autistic children to a pediatrician. However, the children usually have even more difficulty with nonverbal communication; infants and toddlers almost always have problems processing other people’s gestures or facial expressions of emotion and appropriately using such gestures or expressions themselves. Overall, the way in which people with autism attain and use language varies greatly. Most autistic children never develop speech or use only a few words and gestures. Substantial numbers attain partial, restricted, and highly deviant communication skills. For example, they may speak mostly in seemingly meaningless repeated phrases, though sometimes caregivers can learn to decipher these vocalizations in context. Very high functioning autistic children may, by age 2, have some words for greeting, identifying caregivers, or stating a few specific requests. By age 6, these children can attain some receptive and expressive verbal language, and eventually acquire normal or near-normal vocabulary and syntax. Yet even they retain subtle deficits: poor comprehension of abstract ideas and the vocabulary of emotions, inferences, intuition, and metaphors. They may have difficulty generalizing information beyond the immediate context in which they learned it. Even the most high-functioning people with autism have problems with the nonverbal aspects of communication, such as body language, and providing enough contextual information for others to understand what they are talking about. Imaginative Play Most low-functioning autistic children develop little or no imaginative play, a feature of normal child development. At 4 years of age, an autistic child might pick up a toy car and put it in his or her mouth, or turn it upside down and spin its wheels in fascination for several minutes. A high-functioning 4-year-old might gather many toy cars in a corner and make imitation car sounds, showing awareness that the toys represent real cars—but do that over and over and resist letting anyone bring another toy car to interact. Only the highest-functioning autistic children develop true imaginative play. Unusual Patterns Younger autistic children are likely to engage in repetitive behavior, sometimes referred to as self-stimulation, such as flapping their hands excitedly, rocking back and forth, or spinning. Also common are clutching or flapping a favorite object, even if it is simply a piece of plastic trash bag. In general, such behaviors seem to increase when the child is excited or under stress. Related behavior includes fascination with spinning wheels and fans or opening and closing window blinds. However, a sizable minority of autistic children either never exhibit any of these sensory obsessions or grow out of them. Unusual perceptual problems are also a common feature, particularly in younger children. They may not be able to tolerate bright lights, certain sounds, or sensing some fabrics against their skin. Often the same youngsters may have a greatly elevated pain threshold. These unusual sensory patterns are not considered diagnostic of autism, but they occur often enough to suggest a dysfunction in the way the brain processes information from the senses. In some low-functioning autistic individuals, self-stimulation can veer toward compulsive self-inflicted injury by hitting, biting, banging their heads on the floor or walls, or other actions. Such behavior is frightening and frustrating for parents. It constitutes a psychiatric emergency. Self injurious actions are not unique to autism, however; some severely mentally retarded individuals also display them. Some autistic people show a preference for highly structured, predictable, and repetitive routines, which at times is essentially indistinguishable from obsessive-compulsive behavior. Many autistic individuals become very distressed when their customary routines are disrupted, or when they must change activities. Others insist that all objects in a room remain in the same positions at all times. Many people with autism have behavior problems, often quite severe, that are common in the nonautistic population. Treating these problems separately, even though they may derive from the same underlying neurodevelopmental pathology, is one of the most helpful ways to intervene in autism. The most common of these are attention deficits and impulsive, hyperactive, and distractible behavior. Anxiety and panic disorders and mood disorders are also widespread. Causes Whether autism is present at birth or arises after normal early development is still unsettled. About 20 percent of parents with an autistic child report that he or she developed normally for one or two years, although in many of these cases the parents may have overlooked the condition’s subtle early signs. Nevertheless, some autistic people appear to have developed normally in infancy. In fact, there are rare reported cases of autism starting after age 3. Late-onset cases do not seem to differ in their clinical features or prognosis for improvement, however. Very strong evidence suggests that autism has a genetic basis. About 20 percent of cases occur in association with illnesses we know are inherited, most commonly fragile X syndrome and tuberous sclerosis (though only a minority of people with these conditions develop autism). Phenylketonuria (PKU) is an inherited metabolic disorder that, when untreated, leads to autism and severe mental retardation; fortunately, most babies are tested at birth for this condition, and a medically regulated diet prevents the severe brain damage. About 80 percent of autism cases are idiopathic (caused by unknown mechanisms), but there is still evidence that most cases are inherited. When one identical twin has autism, the odds of the other having it range from 60 percent to 90 percent. In contrast, the concordance rate found for fraternal twins and siblings ranges from 2 percent to 5 percent—and even that rate is 50 to 100 times higher than the rate in the general population. Recent research has shown that siblings, parents, and other close relatives of people with autism have an unusually high rate of learning disabilities, language delays, and impaired social skills. After several large genetic studies, only a few genes have been weakly associated with autism, which strongly implies that several genes in combination must produce the disorder. The preponderance of males with PDDs compared with females raises suspicion that the X chromosome, of which males have only one copy while females have a “backup,” contains high-susceptibility genes. However, genetic research has not borne this out. There may actually be several different genetic types of autism. The evidence for brain abnormalities underlying autism is impressive. Eighty percent of people with autism are also mentally retarded, reflecting neurodevelopmental defects or brain damage. Many of these have very severe intellectual impairment. By adulthood, between 20 percent and 35 percent of people with autism have experienced seizures, much more than in the general population. Imaging studies (most recently using magnetic resonance imaging, or MRI) have supplied more evidence of brain abnormalities in autism. Most studies find that autistic individuals have larger overall brains than other people, especially in the posterior regions. The rear portions of the corpus callosum (the main connecting fibers between the two sides of the brain) are smaller in autistic people. These findings have caused researchers to propose that autism involves failures in the neurons’ migration or in pruning before birth or in the early months of life. Many cases of autism are also associated with specific brain lesions (certainly the case for tuberous sclerosis) and other malformations, but we do not know the significance of these in how autism develops. Diagnosis Diagnosing autism and other PDDs early, in the preschool period, is crucial for providing children with the intensive early intervention they need to improve their functioning. While there is still no cure for autism, we have made much progress in helping children with PDDs develop, learn, and adapt to the world. There are really two stages to diagnosing PDDs. First, child psychiatrists or clinical child psychologists who have received specialized training must recognize and confirm the condition. This requires systematically obtaining information from parents, caregivers, and perhaps teachers and interviewing the child. There is no biological test to confirm a PDD diagnosis (except for the rare case of Rett’s disorder). However, a physician may request laboratory tests to check for associated genetic disorders or seizure disorder. Recently, psychiatrists have made considerable progress in creating short and convenient screening tests for autism and other PDDs. These are essential in helping pediatricians identify autism in very young children. The most extensive comprehensive interview in widespread use is the Autism Diagnostic Instrument (ADI), a detailed review based on interviewing parents about all symptoms and behaviors associated with autism. The second stage in diagnosing PDDs is determining exactly how a child is affected and how severely. Every child has different abilities, and it is important to recognize those in order to help him or her make the most of them. Recommending ways to help the child often requires the collaboration of the child’s psychiatrist, pediatrician, or pediatric neurologist, cognitive and behavioral psychologists, speech and language specialists, and occupational therapists. A diagnostic report on a child with autism has enormous practical significance. Parents and public agencies rely on it in making major decisions about early intervention, school placement, special education, and access to community services. A child should have individualized treatment and education, not a “one size fits all” plan. Treatment and Teaching Drug therapy has a role in treating autistic behavioral problems, but no evidence shows it affects underlying autism. The greatest obstacle to effective drug treatment in autism is the mistaken assumption that all behavioral problems that autistic people have are part of the disorder. Parents should be aware that autistic children have an increased likelihood for abnormal responses to medications. For example, while selective serotonin reuptake inhibitors (SSRIs) are often effective in reducing anxiety, repetitious behavior, and tantrums, much anecdotal evidence exists that for some people they actually increase the behaviors. Sedatives seem more likely to provoke what is termed a paradoxical reaction, of silly or out-of-control behavior, while other medications produce sedative side effects, which can interfere with a child’s attention and learning. Parents of autistic children face extraordinary challenges: managing their child’s difficult behavior, spending extra time assisting him or her in self-care routines, maintaining composure when their child displays odd behaviors or tantrums in public, accepting that he or she cannot express normal affection, and advocating for their child’s education, often in underfunded, resistant school systems. One major advance in the treatment of autism has been the rise of strong, well-organized parent advocacy groups offering a range of support services. Early-intervention programs involving intensive one-on-one behavioral lessons for 10 to 40 hours each week have shown considerable success with many autistic preschoolers, particularly those who are higher functioning. Using positive reinforcement, the trainer first teaches a child to follow verbal or gestural instructions, then trains him or her in a graded series of communication, thinking, and social skills. Very encouraging data also support the efficacy of specially designed preschool programs that foster communication and social skills. Other, more psychotherapeutically oriented programs rely on intensive parent-child interventions, such as training parents in extensive floor play with their young preschoolers; these programs have resulted in less scientific documentation of improvement. Many of these programs demand major time commitments in a child’s critical preschool years, and parents must evaluate them carefully because the time and expense may effectively rule out other approaches. Language and communication therapy includes training in everyday communication through individual and small-group therapy. Use of sign language, pictures, and both manual and computer-assisted communication boards creates rewarding ways for nonverbal children to communicate. While many low-functioning autistic children will probably always have severe communication deficits, some can learn to point and make simple requests, greatly improving their own and their families’ lives. A variety of educational interventions are in use. One widely used model involves specially designed classrooms and predictable, behaviorally reinforced lessons. All children with autism should have their schooling planned and reviewed through the individualized educational program (IEP) defined by law. Most advances in psychotherapy and drug treatments for autistic children target their very common behavioral problems, including disruptive behavior disorders, anxiety and phobias, obsessional rituals, tantrums, mood swings, and self-injurious behaviors. These disorders often affect family life more than the direct symptoms of autism. In some communities behavioral therapists are available to go into homes after school to assist parents in developing improved behavior management strategies and to reinforce training in self-care skills. Very high functioning older autistic children and adolescents can sometimes benefit from individual psychotherapy. Such individual therapy usually emphasizes counseling for more effective socializing, as well as direct modeling and role-playing to increase social coping skills.
Keywords:
autism, autistic, spectrum disorder, asd, symptoms, socialization, communication, repetitive behaviors, cause, diagnosis, manifestation, treatment
Creative Commons License This work by Cold Spring Harbor Laboratory is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.

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