Autism
Overview
Autism, also called infantile autism or autistic disorder, is a lifelong disorder that causes abnormal neurological development. It is one of five pervasive development disorders (PDDs) that also include Asperger's syndrome, childhood disintegrative disorder, Rett disorder, and pervasive development disorder-not otherwise specified (PDD-NOS).Autism is usually diagnosed by the age of 3.
Autism causes impaired social interaction, communication difficulties, and restricted or repetitive activities and interests. People with autism often exhibit abnormal responses to sensory stimulation (e.g., touch, sound, light), usually have moderate mental retardation, and have a higher risk for developing epilepsy. Some autistic patients exhibit aggression and self-injurious behavior (e.g., head banging, biting themselves).
About one-third of patients with autism have normal or nearly normal intelligence quotients (IQs). Many are able to display emotion and affection and respond to their environment. Terms used to describe patients with the disorder include autistic-like, autistic tendencies, autism spectrum, and high-functioning or low-functioning autism.
High-functioning patients may have minor delays in language and development and difficulty with social interactions. They may have problems initiating and maintaining conversation and efforts may be described as "talking at others" (e.g., may talk incessantly about a favorite subject despite attempts by others to speak).
With early intervention and appropriate treatment, some autistic patients are able to learn and function productively. There is no cure for the disorder and most patients require lifelong care.
Incidence and Prevalence
Autism affects 1 to 2 out of every 1000 people and as many as 1.5 million adults and children in the United States have some form of the disorder. The overall incidence increases by about 10-17% each year. The disorder occurs about 4 times more often in boys.
Causes and Risk Factors
The cause of autism is unknown. The disorder results from abnormalities in brain structure or function and the underlying cause usually cannot be identified. Patients with autism often have abnormalities in several areas of the brain. This may indicate that a disruption in fetal brain development contributes to the disorder.
Brain abnormalities may result from genetic (hereditary) or environmental (e.g., exposure to toxins) factors, metabolic disorders (e.g., serotonin deficiency), viral infections (e.g., German measles), or complications during pregnancy and delivery.
A single gene for autism has not been identified, but a group of unstable genes may trigger the disorder in some patients.
The measles-mumps-rubella vaccine (MMR) may contribute to autism in some cases. More research is necessary to evaluate this potential risk factor.
Medical conditions associated with an increased risk for autism include the following:
- Fragile X syndrome (more common in males; may cause mental retardation)
- Tuberous sclerosis (syndrome that causes seizures, mental disorders, and tumors)
- Congenital rubella syndrome (results from transmission of the rubella virus [causes German measles] in utero)
- Untreated phenylketonuria (PKU; hereditary disease caused by a defective enzyme)
Signs and Symptoms
Signs of autism may appear during infancy and the disorder is usually diagnosed by the age of 3. Sometimes the child's development appears normal until about 2 years old and then regresses rapidly. Symptoms of autism occur in various combinations, from mild to severe.
Infants with the disorder often display abnormal reactions to sensory stimuli (i.e., senses may be over- or underactive). Touches may be experienced as painful, smells may be overwhelmingly unpleasant, and ordinary daily noises may be painful. Loud noises (e.g., motorcycle going by, vacuum cleaner) and bright lights may cause inconsolable crying.
Other signs of the disorder in infants include the following:
- Appears indifferent to surroundings
- Appears content to be alone, happier to play alone
- Displays lack of interest in toys
- Displays lack of response to others
- Does not point out objects of interest to others (called protodeclarative pointing)
- Marked reduction or increase in activity level
- Resists cuddling
Young children with autism usually have impaired language development. They often have difficulty expressing needs (i.e., use gestures instead of words) and may laugh, cry, or show distress for unknown reasons. Some autistic patients develop rudimentary language skills that do not serve as an effective form of communication. They may develop abnormal patterns of speech that lack intonation and expression and may repeat words or phrases repetitively (called echolalia). Some children with autism learn to read.
Autistic children do not express interest in other people and often prefer to be alone. They may resist changes in their routine, repeat actions (e.g., turn in circles, flap their arms) over and over, and engage in self-injurious behavior (e.g., bite or scratch themselves, bang their head).
Other symptoms in young children include the following:
- Avoids cuddling or touching
- Frequent behavioral outbursts, tantrums
- Inappropriate attachments to objects
- Maintains little or no eye contact
- Over- or undersensitivity to pain, no fear of danger
- Sustained abnormal play
- Uneven motor skills
- Unresponsiveness to normal teaching methods and verbal clues (may appear to be deaf despite normal hearing)
Symptoms of autism may increase in severity when the child enters adolescence and often decrease in severity during adulthood.
Diagnosis
Diagnosis of autism is usually made by the age of 3. Early diagnosis and treatment often helps to improve outcome for patients. Diagnosis includes the following:
- Physical examination (may include neurological examination)
- Medical history (includes family history, birth history, and early development)
- Medical tests (to rule out other conditions)
Physicians use various screening tools to evaluate development, communication and language skills, and interaction with others. They usually question caregivers about the child's development (e.g., Did the child babble, point, wave, and grasp objects by 12 months of age?) and observe the child closely during office visits.
Differential Diagnosis
Conditions that cause symptoms similar to autism include the following:
- Asperger's syndrome
- Childhood disintegrative disorder
- Rett disorder
- Pervasive development disorder-not otherwise specified (PDS-NOS)
- Childhood psychoses (e.g., schizophrenia)
- Fragile X syndrome (more common in males; may cause mental retardation)
- Hearing loss
- Metabolic disorders
Tests performed to rule out other conditions include the following:
- Blood tests (to rule out metabolic disorders that affect amino acids and lipids in the blood)
- Chromosomal analysis (to rule out genetic disorders)
- Comprehensive hearing test (to rule out deafness as the cause of abnormal language development)
- Electroencephalogram (EEG; to rule out seizure disorder)
- Magnetic resonance imaging (MRI scan; to rule out brain disorders)
Asperger's syndrome is sometimes considered a variation of autism. It is more common in boys, usually develops after the age of 3, and usually does not require lifelong care. Children with Asperger's have narrow interests, repetitive routines, and are at increased risk for developing depression and anxiety. Symptoms include the following:
- Excellent rote memory (usually)
- Excellent musical ability (often)
- Inability to use language to communicate
- Lack of facial expressions and emotion
- Limited interests and an intense interest in one or two areas
- Severely impaired social interaction
- Undeveloped motor skills
Childhood disintegrative disorder causes marked deterioration of intellectual, social, and language skills around the age of 3 or 4. The disorder is associated with seizures and is more common in boys. Patients with the condition usually require lifelong care. Childhood disintegrative disorder causes loss of the following:
- Bowel and bladder control
- Language (i.e., ability to communicate and understand others)
- Motor skills
- Social skills (e.g., ability to play, develop peer relationships)
Rett disorder is a progressive neurological disorder that occurs only in girls. Symptoms of the disorder usually develop between 6 and 18 months of age. It is characterized by the following:
- Abnormal gait
- Inability to control hand movements
- Inability to express feelings
- Reduced brain size and weight (microcephaly)
- Reduced muscle tone (hypotonia)
- Seizures
Patients also may experience constipation, breathing difficulties, weakness of the extremities, and cognitive regression. There is no cure for Rett disorder, but symptoms usually can be managed with appropriate treatment.
Pervasive developmental disorder-not otherwise specified (PDD-NOS) is characterized by delayed development of social and communication skills. It usually develops between 2 and 12 years of age. Individual attention and medication to manage behavioral problems can be beneficial. Symptoms include:
- Abnormal play behavior
- Desire for sameness in their environment
- Difficulty using and understanding language
- Impaired ability to relate to people, objects, and events
- Repetitive movement and behavior
- Self-injury
- Unusual mannerisms
Treatment
There is no cure for autism; however, with appropriate treatment and education, many children with the disorder can learn and develop. Early intervention often can reduce challenges associated with the disorder, lessen disruptive behavior, and provide some degree of independence.
Treatment depends on the individual needs of the patient. In most cases, a combination of treatment methods is more effective. Autism usually requires lifelong treatment.
Occupational therapy and physical therapy are sometimes used to treat autism. Occupational therapy helps improve independent function and teaches basic skills (e.g., buttoning a shirt, bathing). Physical therapy involves using exercise and other physical measures (e.g., massage, heat) to help patients control body movements.
Treatment includes the following:
- Behavior modification
- Communication therapy
- Dietary modifications
- Medication
Behavior modification
There are several methods of behavior modification that are used to treat inappropriate, repetitive, and aggressive behavior and to provide autistic patients with skills necessary to function in their environment. Most types of behavior modification are based on the theory that rewarded behavior is more likely to be repeated than behavior that is ignored. This theory is called applied behavior analysis (ABA).
Behavior modification often involves highly structured, skill-oriented activities that are based on the patient's needs and interests. It usually requires intense, one-on-one training with a therapist and extensive caregiver involvement.
Sensory integration therapy is a type of behavior modification that focuses on helping autistic patients cope with sensory stimulation. Treatment may include having the patient handle materials with different textures or listen to different sounds.
Social interaction is often affected by limited emotional development that is common in autistic patients. Play therapy is a type of behavior modification that is used to improve emotional development, which in turn, improves social skills and learning. Play therapy involves adult-child interaction that is controlled by the child.
Social stories can also be used to improve undeveloped social skills. Stories are designed to help autistic patients understand the feelings, ideas, and points of view of others, or to suggest an alternate response to a particular situation. They also may be used to help patients understand and cope with their own feelings. Behavioral therapists can teach caregivers how to develop social stories.
Communication therapy
Communication therapy is used to treat autistic patients who are unable to communicate verbally, or to initiate language development in young children with the disorder. Speech therapy may be used to help patients gain the ability to speak.
Picture exchange communication systems (PECS) enable autistic patients to communicate using pictures that represent ideas, activities, or items. The patient is able to convey requests, needs, and desires to others by simply handing them a picture.
Dietary modifications
Autism is not caused by diet and the use of dietary modifications and supplements to treat the disorder is controversial. Changing the diet or adding vitamin supplements may improve digestion and eliminate food intolerances or allergies, which may contribute to behavioral problems in autistic patients.
Researchers have found elevated levels of proteins found in wheat, oats and rye (gluten) and casein (protein in dairy products) byproducts in patients with autism, suggesting that the incomplete breakdown or excessive absorption of these substances may affect brain function. Eliminating foods that contain gluten and casein from the diet may cause side effects and should not be done without the advice of a health care practitioner.
Studies have shown that vitamin B, magnesium (improves the effects of vitamin B), and cod liver oil supplements (which contain vitamins A and D) may improve behavior, eye contact, attention span, and learning in autistic patients. Vitamin C has been shown to improve depression and lessen the severity of symptoms in patients with autism.
Medication
Medication may be used to treat various symptoms of autism (e.g., attention difficulties, anxiety) and can also be used to treat conditions that may accompany the disorder (e.g., epilepsy).
Depression, obsessive-compulsive behavior, and anxiety may be treated using antidepressants. These drugs often reduce the frequency and intensity of repetitive behavior; decrease irritability, tantrums, and aggression; and improve eye contact and responsiveness. Side effects include headache, insomnia, dizziness, and drowsiness. Medications include the following:
- Amitriptyline (Elavil®)
- Bupropion (Wellbutrin®)
- Clomipramine (Anafranil®)
- Fluvoxamine (Luvox®)
- Fluoxetine (Prozac®)
Benzodiazepines such as diazepam (Valium®), lorazepam (Ativan®), and alprazolam (Xanax®) may also be used to treat behavioral problems. Side effects include drowsiness, fatigue, lack of muscle coordination (ataxia), and dizziness. Discontinuing these drugs after long-term use may cause withdrawal symptoms including:
- Abdominal and muscle pain
- Convulsions and tremors
- Insomnia
- Sweating
- Vomiting
Antipsychotic medications such as clozapine (Clozaril®), risperidone (Risperdal®), olanzapine (Zyprexa®), and quetiapine (Seroquel®) may decrease hyperactivity, behavioral problems, withdrawal, and aggression in autistic patients. Side effects include the following:
- Agitation
- Anxiety
- Drowsiness
- Dizziness
- Headache
- Insomnia
- Sedation
Stimulants such as methylphenidate (Ritalin®), amphetamine (Adderall®), and dextroamphetamine (Dexedine®) may also be prescribed for autism. These drugs may increase focus and decrease impulsivity and hyperactivity in high-functioning patients. Prolonged use of stimulants may lead to drug dependence. Side effects are often dose-related and include the following:
- Abdominal pain
- High blood pressure (hypertension)
- Insomnia
- Loss of appetite
- Nervousness
- Rapid heart rate (tachycardia)
Prognosis
Patients with autism have normal life expectancies. With early intervention and appropriate treatment, some autistic patients can function productively and attain some degree of independence. Most patients require lifelong assistance.