Overview of Autism Spectrum Disorders

All Autism Spectrum Disorders (also known as pervasive developmental disorders) are characterized by varying degrees of impairment in communication skills and social interactions as well as restricted, repetitive or stereotyped patterns of behavior. The label "Autism Spectrum Disorder" actually applies to five different, but related, conditions.  These conditions range from the more severe Autistic Disorder, to the milder Asperger Syndrome, and also include PDD nos, Rett syndrome, and Childhood disintegrative disorder. Most autism spectrum disorders can be reliably detected by the age of 3 years, and sometimes much earlier.  New studies suggest that many children may eventually be accurately identified by 1 year of age or younger.  

Parents are often the first to notice odd or unusual behaviors in their child. Some parents may not notice any differences until the child is 1 1/2 or 2, when he or she would be expected to begin speaking.  In other cases, parents report that the baby seemed “different” from birth, unresponsive to people or focusing intently on one item for long periods of time.  Still other children regress into autism, developing typically and then losing language skills and becoming withdrawn over a period of a few months or weeks. When a toddler suddenly becomes silent, withdrawn, or loses language skills, there is a problem that needs prompt attention. Research has shown that parents are usually correct about noticing developmental problems in their children. 

Below are more detailed descriptions of each of the five ASDs (Autism Spectrum Disorders):

Autism

Autism is a lifelong developmental disorder that affects an individual’s abilities in the areas of communication and social interaction. Leo Kanner first described it in 1943. In his study of eleven boys, he distinguished it from childhood schizophrenia. Criteria for diagnosis are arranged under three categories: social interaction; communication; and restricted, repetitive and stereotyped behaviors and interests. An additional criterion specifies the onset to have occurred before the age of three years. Autism occurs in 2-5 per 10,000 live births, and 3-4 times more often in boys than girls. It is the third most common developmental disability.  Cognitive impairment often co-occurs with autism; 70-75% of people with autism also have mental retardation (IQ below 70). Fifty percent of individuals with autism develop functional communicative language. Autism is
a spectrum disorder with symptoms ranging from mild to severe. The term high functioning autism is not a diagnostic term, but is used to refer to individuals who have autism and normal to above normal intelligence. The exact cause of autism is unknown; however, research has determined that it has a biological cause and it is not psychological. While there are many strategies that assist an individual to learn important functional skills, there is no treatment or intervention strategy that cures autism.  

Autistic Disorder

Asperger’s Disorder
Asperger’s Disorder is a developmental disorder that is characterized by a severe impairment in the areas of social interaction and restricted and unusual patterns of interest and behavior. Dr. Hans Asperger, a pediatrician from Vienna, Austria, first described this disorder in 1944, one year after Leo Kanner first wrote about autism. At the time they were unaware of each other’s work, but their patients shared many commonalities. However, the children that Asperger observed were not as delayed in speech, and the onset seemed to be later than the children studied by Kanner.

Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS)
Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS) is diagnosed when an individual has a severe and pervasive impairment in the development of reciprocal social interaction or verbal and nonverbal communication skills, or when behavior, interests, and activities are present, but the criteria are not met for a specific Pervasive Developmental Disorder. This category also includes “atypical autism,” for example, presentations that do not meet the criteria for Autistic Disorder because of late age of onset, atypical symptomatology, or subthreshold symptomatology. A common misunderstanding about PDD-NOS is that it is “mild autism.” This is not accurate. Although PDD-NOS is a separate diagnosis from autism, the same interventions may be effective for both diagnoses.

Rett’s Disorder (Rett Syndrome)
Rett’s Disorder is a developmental disorder that occurs almost exclusively in females in 1 per 22,800 live female births. Severe impairment of receptive and expressive communication and apraxia (dyspraxia) are characteristic of Rett’s Disorder. The child has a period of normal development until age 5 months. Within 6- 30 months the child’s development stops or regresses. The child loses communication skills, which may be mistaken for hearing loss, and purposeful use of the hands. Stereotyped hand movements (hand wringing or hand washing), poor coordination of gait, and a slowing of the rate of head growth appear following the regression. Seizures and disorganized breathing patterns may also occur. Rett’s Disorder is most often misdiagnosed as autism, cerebral palsy, or non-specific developmental delay. It was first described by Dr. Andreas Rett from Vienna, Austria and was recognized throughout the world in 1983. The October 1999 issue of Nature Genetics (Vol. 23) reports that the protein MeCP2 is responsible for Rett’s Disorder. This establishes Rett’s Disorder as the first human disease caused by defects in a protein involved in DNA methylation. The research also supports Rett’s Disorder being added to a small but growing number of human genetic disorders that involve abnormal chromatin packaging and gene expression.

Childhood Disintegrative Disorder
Dr. Theodore Heller first identified Childhood Disintegrative Disorder (CDD),
also known as Heller’s Syndrome, in 1908 in Vienna, Austria. CDD is characterized by regression in development after at least two years of normal development. Prior to the regression, the child exhibits age-appropriate play and communication skills. The loss of skills usually develops gradually before the age of 10 years in at least two of the following areas: expressive or receptive language, social skills, bowel or bladder control, play skills, or motor skills. A period of unspecified anxiety or agitation may occur prior to the regression. Generally, the regression occurs between the ages of three and five years. Following the loss of skills, CDD is difficult to distinguish from autism. Therefore, the history of the child’s development is critical to an accurate diagnosis. Childhood Disintegrative Disorder has a prevalence rate of 1 per 100,000 births, affecting more males than females.