Types of Autism/Asperger's

Autism and the related autism spectrum disorders (ASD) constitute a group of five categories referred to as pervasive developmental disorders (PDD). These disorders involve social and language impairment, as well as restricted and repetitive behavior, interests and activities.
Because the disorders display similar traits, the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) classifies them not according to distinct symptoms, but to the number of symptoms displayed, along with the level of intelligence and adaptive functioning.

Features

• Children usually display autistic symptoms around the age of 2. Although the exact cause or causes of the disorder remain unknown, according to the Centers for Disease Control and Prevention (CDC), current research fails to link the main cause of autism to outside agents, such as viruses or poisons. However, the Autism Genome Projects, partially funded through the National Institutes of Health (NIH), has undertaken a massive study that proposes a genetic link associated with this disorder.

Considerations

• Autism and autism spectrum disorders are not diseases but are neurological disorders that impair several developmental areas, such as language and social skills. According to the National Institute of Mental Health (NIMH), in this country, autism affects approximately 1 in 1,000 children and possibly as many as 1 in 500---more common than childhood cancer, diabetes or Down syndrome.

Identification

• Diagnosing PDDs remain difficult due to the wide spectrum of symptoms also associated with other mental disorders, as well as the degree of impairment, such as mild to severe mental retardation. Nevertheless, clinicians employ various tests and checklists. For example, a clinician may use a physical examination that measures head circumference, weight and height. Some may include clinic observations to record the developmentally delayed child in different situations. In addition, a hearing test may be administered to rule out hearing difficulties associated with developmental delays instead of a PDD disorder.

Types

• The DSM-IV categorizes five pervasive developmental disorders: Autism, Asperger's syndrome, Rett syndrome, childhood disintegrative disorder, and pervasive developmental disorder not otherwise specified (PDDNOS).
  Diagnosed before age 3, autism affects communication skills with the child often displaying a delayed or complete lack of speech. In addition, the child exhibits a strong reliance on rituals and routines along with repetitive speech and movements, such as finger flicking.
  Conversely, Asperger's syndrome is diagnosed later than other ASDs, often during school years, due to the child displaying normal intelligence and speech. However, the individual displays a lack of social skills, such as failing to appreciate nonverbal social cues, as well as compulsive and restricted interests.
  Rett syndrome, although rare, affects mainly females between 6 and 12 months old. After following normal development, the child regresses in a range of developmental domains affecting intelligence, coordination, movement and speech.
  Childhood disintegrative disorder (CDD) is also rare, and mainly affects males. This disorder follows a distinct onset and progression of deterioration of skills, starting usually around 3 to 4 years old. The skill areas affected include language, social and motor. Often times, the child loses bowel and bladder control.
  Pervasive developmental disorder not otherwise specified features many, but not all, of the characteristics associated with autism spectrum disorders. The only specified standards include impairments in social relatedness and in some aspects of communicative or behavioral development and functioning.

Misconceptions

• Due to the early onset, between 1 and 2 years of age, as well as the reported rise in the number of children affected by ASDs, some researchers proposed a link with childhood vaccinations. For example, a study by medical researcher Andrew Wakefield and colleagues suggested a relationship between the measles/mumps/rubella (MMR) vaccine and autism. However, according to the National Institute of Child Health and Development, currently, "there is no definite, scientific proof that any vaccine or combination of vaccines can cause autism."