Autism

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Autism

Definition

Autism is a potentially severe neurological condition affecting social functioning, communication skills, reasoning, and behavior. It is considered a spectrum disorder, meaning that the symptoms and characteristics of autism can present themselves in a variety of combinations, ranging from extremely mild to quite severe.

Description

Autism is a neurological disorder that affects a persons ability to communicate and form relationships. Individuals with autism have deficits in social interaction, communication, and understanding. Some individuals with autism have unusual repetitive behaviors, such as head banging, rocking, and hand-flapping. Up to 75–80% of individuals with autism are mentally retarded; only a small portion of this group (15–20%) have severe mental retardation. Additionally, over one-third of individuals with autism will develop seizures in early childhood or adolescence.

There is a wide degree of variability in the specific symptoms of autism. Because of this variability, autism is considered a spectrum disorder. There is no standard type or form of autism. Each individual is affected differently. This variability is reflected in some of the terms or names for autism. Asperger syndrome is a term used to describe individuals with autism with language skills. Pervasive developmental delay (PDD) is the term that is often used interchangeably with autism. The different terms for autism are partly due to the different individuals that first described this disorder.

Autism was first described by Leo Kanner in 1943. He observed and described a group of children with a pattern of symptoms. These children had some unique abilities and did not seem to be emotionally disturbed or mentally retarded. He invented the category early infantile autism (sometimes called Kanner's syndrome) to describe these children. In a strange coincidence, Hans Asperger made the same discoveries in the same year. He also described children with a unique behavioral profile and used the term autism to describe them. His original study was in German and was not translated into English until the late 1980s. Because the children that he identified all had speech, the term Asperger syndrome is often used to label autistic children who have speech.

While the effects of this disorder may vary in intensity, all individuals with autism have deficits in three key areas: social interaction, communication, and reasoning. In addition to these neurologic problems, individuals with autism often exhibit bizarre repetitive movements such as hand-flapping or head-banging. Other characteristics include a need for sameness or routine. While most individuals with autism have deficits, there are affected individuals that display unusual talents in areas such as math, music, and art. Some children have extraordinary talent in drawing and others learn to read before they learn to speak. These talents usually coexist with the other deficits of autism and are rare. These are usually referred to as savant skills.

Social interaction is the ability to interact, both verbally and nonverbally, with other humans. Individuals with autism have problems recognizing social cues such as facial expressions and tone of voice. Individuals with autism are often described as "being in their own world." This sense of isolation may arise from their inability to communicate effectively. They also lack the motivation for reciprocal communication.

Individuals with autism also have communication and language problems. They may or may not develop speech. Those individuals with autism that do speak use language in unusual ways. They may echo the comments of others (echolalia) or use phrases inappropriately. People with autism often use pronouns such as I, me, and you incorrectly. In addition to problems developing speech, individuals with autism have problems understanding the purpose of speech.

Individuals with autism can also have hyperacute senses. They may be very sensitive to bright lights, loud noises, or rough textures. The self-stimulating behaviors (head banging, hand flapping, rocking) sometimes seen in individuals with autism may be attempts to calm themselves due to over-stimulation. Other characteristic behaviors can include throwing temper tantrums for no apparent reason and developing fixations or obsessive interests.

The cause of autism is unknown. Originally, it was hypothesized that autism was a psychological problem caused by defective parenting. This hypothesis has been discredited as scientific information about neurological differences and biologic causes for autism have emerged.

Genetic profile

Although the search has been extensive, as of 2005, no single specific gene for autism has been discovered. Several candidate genes and chromosomal regions have been identified, but much research is needed before the exact roles that these genes play in the development of autism are understood.

Although the exact cause of autism is unknown, it is thought that autism occurs due to a combination of genetic and environmental causes. This combination of causative factors is often referred to as multifactorial inheritance . There are probably a number of different genes as well as unknown environmental factors involved in the development of autism. Multifactorial conditions tend to run in families, but the pattern of inheritance is not as predictable as with single-gene disorders. The chance of recurrence is also less than the risk for single-gene disorders and is usually derived from empiric or long-term studies of a large number of families.

Twins studies are used to determine the degree of heritability of a disorder. Identical twins have the exact same genes, while fraternal (non-identical) twins have only half of their genes in common. By examining the rates of concordance (the number of twin pairs that both have autism), it is possible to determine if there is a genetic component to autism. Studies that looked at the incidence of twins with autism determined that identical twins are more likely to be concordant (both affected) with autism than fraternal twins. This means that individuals with the same genes both have autism more often than twins with only half of the same genes. This finding suggests that genes play a role in the development of autism.

Identical twin pairs with autism reveal that there is a genetic component to autism. However, if autism was purely genetic, then all identical twins would be affected with autism (concordant). The fact that there are some identical twin pairs that are discordant for autism (one twin has autism and the other does not) means that other factors (possibly environmental) besides genes must also play a role in causing autism.

Speculations as to what other factors might influence or cause an individual to become autistic include viral, immunologic (including vaccinations), and environmental factors. While there are many theories about possible causes for autism, as of 2005, no specific non-genetic causes have been found and there is no scientific evidence for any specific environmental factor being a causative agent. Research in this area is ongoing.

Other scientific studies that point to the role of genes in the cause of autism look at the recurrence risk for autism. A recurrence risk is the chance that the same condition will occur for a second time in the same family. If a disease has no genetic component, then the recurrence risk should equal the incidence of the disorder. If autism had no genetic component, then it would not be expected to occur twice in the same family. However, studies have shown that autism does have an increased recurrence risk. In families with an affected son, the recurrence risk to have another child with autism is 7%. In families with an autistic daughter, the recurrence risk is 14%. In families with two children with autism, the chance that a subsequent child will also be affected is around 35%. Increased recurrence risks in families with one child with autism indicates that there is some genetic component to autism.

Genetic syndromes with autistic behaviors

While no specific gene has been found to cause isolated autism, there are some genetic syndromes in which the affected individual can have autistic behaviors. These genetic syndromes include untreated phenylketonuria (PKU), fragile X syndrome , tuberous sclerosis, Rett syndrome , and others.

Phenylketonuria is an inborn error of metabolism. Individuals with PKU are missing an enzyme necessary to break down phenylalanine, an amino acid found in protein-rich food. As these individuals eat protein, phenylalanine builds up in the bloodstream and nervous system, eventually leading to mental retardation and autistic behaviors. Most infants in the United States are tested at birth, and those affected with PKU are treated with a protein-free diet. This disorder is more common among individuals of northern European descent. The vast majority of infants in the Unites States are identified as having PKU through a newborn screening test done shortly after birth.

Fragile X syndrome is a mental retardation syndrome that predominantly (but not exclusively) affects males. Males with fragile X syndrome have long narrow faces, large cupped ears, enlarged testicles as adults, and varying degrees of mental retardation. Some individuals with fragile X syndrome also display autistic behaviors. The gene for fragile X syndrome, FMR1, is located on the X chromosome . DNA testing is available for this condition and will identify over 99% of individuals affected by fragile X syndrome.

Tuberous sclerosis is a variable disease characterized by hypopigmented skin patches, tumors, seizures, and mental retardation in some affected individuals. Up to 25% of individuals with tuberous sclerosis have autism. The genes for tuberous sclerosis have been identified as TSC1 and TSC2. DNA testing is available for this condition and will identify between 60–80% of individuals with tuberous sclerosis.

Rett syndrome is a progressive neurological disorder that almost exclusively affects females. Girls with Rett syndrome develop normally until the age of 18 months and then undergo a period of regression with loss of speech and motor milestones. Girls with Rett syndrome exhibit a nearly ceaseless hand-washing or hand-wringing motion. They also have mental retardation and can have autistic behaviors. The gene for Rett syndrome has been identified as MECP2. DNA testing is available for this syndrome and will identify approximately 80% of individuals with this syndrome.

While individuals with these genetic syndromes can have autistic behaviors, it is important to remember that 70–90% of individuals with autism do not have an underlying genetic syndrome as the cause of their disorder. Many studies are underway to try and determine the etiology or cause of autism.

Demographics

The exact incidence of autism is not known. Because the diagnostic criteria for autism has changed and broadened over the years, studies done to determine the incidence have yielded different estimates. Using the newer, more inclusive criteria, it is estimated that one in 500 individuals are affected with autism and that over half a million individuals in the United States fit the diagnostic criteria for autism, PDD, or Asperger syndrome.

Boys are affected with autism three times more often than girls. While boys may be affected more often, girls with autism tend to be more severely affected and have a lower IQ. The reasons for these differences are not known. Autism occurs in all racial, social, and economic backgrounds.

Signs and symptoms

One of the most frustrating aspects of autism is the lack of physical findings in individuals with autism. Most individuals with autism have normal appearances, and few, if any, medical problems. Because the specific cause of autism is unknown, there is no prenatal test available for autism.

Autism is a spectrum disorder. A spectrum refers to the fact that different individuals with a diagnosis of autism can have very different abilities and deficits. The spectrum of autism stretches from a socially isolated adult with normal IQ to a severally affected child with mental retardation and behavioral problems. The following is a partial list of behaviors seen in individuals with autism divided into main areas of concern. It is unlikely that any one individual would exhibit all of the following behaviors. Most affected people would be expected to exhibit some but not all of the behaviors.

In the area of communication skills, behaviors autistic individuals may display include:

language delay or absence
impaired speech
meaningless repetition of words or phrases
using gestures rather than words to communicate
concrete or literal understanding of words or phrases
inability to initiate or hold conversations

In the area of social interaction, behaviors autistic individuals may display include:

unresponsiveness to people
lack of attachment to parents or caregivers
little or no interest in human contact
failure to establish eye contact
little interest in making friends
unresponsiveness to social cues such as smiles or frowns

In the area of play, behaviors autistic individuals may display include:

little imaginative play
play characterized by repetition (e.g., endless spinning of car wheels)
no desire for group play
no pretend games

Autistic individuals may display behaviors that include:

repetitive motions such as hand flapping and head banging
rigid or flaccid muscle tone when held
temper tantrums or screaming fits
resistance to change
hyperactivity
fixates or develops obsessive interest in an activity, idea, or person
overreaction to sensory stimulus such as noise, lights, and texture
inappropriate laughing or giggling

Diagnosis

There is no medical test, such as a blood test or brain scan, to diagnose autism. The diagnosis of autism is very difficult to make in young children due to the lack of physical findings and the variable behavior of children. Because the primary signs and symptoms of autism are behavioral, the diagnosis usually requires evaluation by a specialized team of health professionals and occurs over a period of time. This team of specialists may include a developmental pediatrician, speech therapist, psychologist, geneticist, and other health professionals. Medical tests may be done to rule out other possible causes and may include a hearing evaluation, chromosome analysis, DNA testing for specific genetic disorders , and brain imaging scans, including magnetic resonance imaging (MRI), electroencephalogram (EEG), or computed tomography (CT), to rule out structural brain anomalies.

Once other medical causes have been excluded, the diagnosis for autism can be made using criteria from the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM IV). This manual, developed by the American Psychiatric Association, lists abnormal behaviors in three key areas: impairment in social interaction, impairment in communication (language), and restrictive and repetitive patterns of behavior. These behaviors are usually seen in individuals with autism. If an individual displays enough distinct behaviors from the list, they meet the diagnostic criteria for autism. Most individuals will not exhibit all of the possible behaviors and, while individuals might exhibit the same behaviors, there is still a large degree of variability within this syndrome.

The DSM-IV criteria for a diagnosis of autistic disorder require a display total of at least six behaviors from items 1, 2, and 3, with at least two from 1, and one each from 2 and 3.

Under item 1 in the DSM-IV, the criteria are qualitative impairment in social interaction, as manifested by at least two of the following:

marked impairment in the use of multiple nonverbal behaviors such as eye-to-eye gaze, facial expression, body postures, and gestures to regulate social interaction
failure to develop peer relationships appropriate to developmental level
markedly impaired expression of pleasure in other people's happiness

Under the DSM-IV's item 2, the criteria are qualitative impairments in communication, as manifested by at least one of the following:

delay in, or total lack of, the development of spoken language (not accompanied by an attempt to compensate through alternative modes of communication such as gestures or mime)
in individuals with adequate speech, marked impairment in the ability to initiate or sustain a conversation with others
stereotyped and repetitive use of language or idiosyncratic language
lack of varied spontaneous make-believe play or social imitative play appropriate to developmental level

Under item 3, the DSM-IV criteria are restricted repetitive and stereotyped patterns of behavior, interests, and activities, as manifested by as least one of the following:

encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus
apparently compulsive adherence to specific nonfunctional routines or rituals
stereotyped and repetitive motor mannerisms (e.g., hand or finger flapping or twisting, or complex whole-body movements)
persistent preoccupation with parts of objects

Other criteria that help diagnosis autism include delays or abnormal functioning in at least one of the following areas, with onset prior to age three years:

social interaction,
language as used in social communication
symbolic or imaginative play

Autism is the usual diagnosis when there is no findings of Rett disorder or childhood disintegrative disorder (CDD).

Using all these criteria, the diagnosis of autism is usually made in children by approximately the age of two and a half to three; they are originally seen for speech delay. Often these children are initially thought to have hearing impairments due to their lack of response to verbal cues and their lack of speech.

While speech delay or absence of speech might initially bring a child to the attention of medical or educational professionals, it soon becomes apparent that there are other symptoms in addition to the lack of speech. Children with autism are often noticed for their lack of spontaneous play and their lack of initiative in communication. These deficits become more obvious when these children are enrolled in school for the first time. Their inability to interact with their peers becomes highlighted. Behaviors such as hand flapping, temper tantrums, and head banging also contribute to the diagnosis.

Because the criteria to diagnose autism are based on observation, several appointments with health care providers may be necessary before a definitive diagnosis is reached. A specialist closely observes and evaluates the child's language and social behavior. In addition to observation, structured interviews of the parents are used to elicit information about early behavior and development.

Treatment and management

There is no cure for autism. However, autism is not a static disorder. Behaviors can and do modify over time, and educational treatments can be used to focus on appropriate behaviors. The treatments available for individuals with autism depend upon their needs, but are generally long and intensive. While treatments vary, and there is considerable controversy about some treatments, there is uniform agreement that early and intensive intervention allows for the best prognosis. A treatment plan is usually based upon an evaluation of the child's unique abilities and disabilities.

Standardized testing instruments are used to determine the child's level of cognitive development and interviews with parents and caregivers, as well as observation by health professionals, are used to gauge a child's social, emotional, and communications skills. Once a clear picture of the child's needs is developed, treatment is initiated. Studies have shown that individuals with autism respond well to a highly structured, specialized education program tailored to their individual needs. All treatments are best administered by trained professionals. Speech and language therapy may be used to develop and improve language skills. Occupational therapy may be used to develop fine motor skills and to teach basic self-help and functional skills such as grooming. Behavior modification, with positive reinforcement, plays a large role in the early treatment of some of the abnormal behaviors of individuals with autism. Other therapies may include applied behavioral analysis, auditory integration training, dietary interventions, medications, music therapy, physical therapy, sensory integration, and vision therapy.

Increasingly, medications are being used to treat some of the symptoms of autism. The drugs that are recommended most often for children with autism include psychostimulants (methylphenidate, pemoline), clonidine, or one of the tricyclic antidepressants (TCAs) for hyperactivity or inattention; beta blockers, neuroleptics, or lithium for anger or aggression; selective serotonin reuptake inhibitors (SSRIs) or TCAs for rituals and preoccupations; and SSRIs or TCAs for anxiety symptoms. One alternative herbal remedy that has been tried with AS patients is St. John's Wort.

In order to be effective, the treatments and therapies must be consistent and reinforced by the family. It is helpful if family members and caregivers receive training in working with and teaching individuals with autism. A team approach involving health care professionals, therapists, educators, and families is necessary for successful treatment of individuals with autism.

Prognosis

The prognosis for individuals with autism is variable but much brighter than it was a generation ago. Overall, the ultimate prognosis of an individual with autism is dependant on their IQ, their communicative abilities, and the extent of their behavioral problems.

Individuals with autism without mental retardation can develop independent living skills. Often these individuals do well and can become self-sufficient if they have good communication skills. Other individuals with autism develop some level of self-sufficiency but may never be able to live independently due to their severe communication or cognitive difficulties. Up to 60% of individuals with autism will require lifelong assistance.

Resources

BOOKS

Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. Washington, DC: American Psychiatric Association, 1994.

Hart, C. A Parent's Guide to Autism. New York: Simon and Schuster, 1993.

Siegel, Byrna. The World of the Autistic Child: Understanding and Treating Spectrum Disorders. Oxford: Oxford University Press, 1998.

ORGANIZATIONS

Association for Science in Autism Treatment. 175 Great Neck Road, Suite 406, Great Neck, NY 11021. (516) 466-4400. Fax: (516) 466-4484. [email protected].

Autism Society of America. 7910 Woodmont Ave. Suite 300, Bethesda, MD 20814-3015. (301) 657-0881 or (800) 3-AUTISM. (April 8, 2005.) <http://www.autismsociety.org>.

Cure Autism Now (CAN) Foundation. 5455 Wilshire Blvd. Suite 715, Los Angeles, CA 90036-4234. (500) 888-AUTISM. Fax: (323) 549-0547. [email protected]. (April 8, 2005.) <http://www.cureautismnow.org>.

National Alliance for Autism Research (NAAR). 414 Wall Street Research Park, Princeton, NJ 08540. (609) 430-9160 or (888) 777-6227 CA: (310) 230-3568. Fax: (609) 430-9163. (April 8, 2005.) <http://www.naar.org>.