Characteristics of Autistic Disorder
Age of Onset
It is typically believed that the disorder is present at birth but a diagnosis of the disorder is extremely difficult to determine until after at least 12 months of age. This is due to the fact that many of the diagnostic criteria concern abilities that do not emerge until later in development.
Prevalence
Studies have found that the prevalence rates range from 3.8 to 60 per 10,000 children. There is also a significant sex difference in the diagnosis of autistic disorder. Boys significantly outnumber girls with ratios ranging from 4:1 to 5:1. Research has also revealed that autism is not related to social class nor to ethnicity.
Comorbidity
Children with autism can also found to be diagnosed with intellectual disabilities (IQ scores below 70) at a rate of 68%. Learning disabilities are also common, with specific impairments in executive function. Anxiety disorders are among the most common to be additionally diagnosed in a child with autism with rates ranging from 7-84%. Autism is also known to coexist, with a rate of 11-39%, with seizure disorders and up to 9% with tic disorders. Approximately 50-70% also have issues with sleep disturbances or sleep disorders. This population of children is also at a higher risk for developing mood disorders and symptoms of attention-deficit/hyperactivity disorder.
Causes
The cause of autism disorder is still relatively unknown. However, there is increasing amounts of research that has found there to be some genetic components to the disorder. Family studies have shown that there is a 3-5% chance of siblings also being diagnosed with the disorder and an even higher rate for twins, with a rate as high as 65%.
A number of biological and environmental causes have also been associated with autism but none of them are definitive to the disorder. These include genetic disorders, prenatal exposure to infections (rubella), prenatal exposure to teratogens (drugs, medications), and brain abnormalities.
It is typically believed that the disorder is present at birth but a diagnosis of the disorder is extremely difficult to determine until after at least 12 months of age. This is due to the fact that many of the diagnostic criteria concern abilities that do not emerge until later in development.
Prevalence
Studies have found that the prevalence rates range from 3.8 to 60 per 10,000 children. There is also a significant sex difference in the diagnosis of autistic disorder. Boys significantly outnumber girls with ratios ranging from 4:1 to 5:1. Research has also revealed that autism is not related to social class nor to ethnicity.
Comorbidity
Children with autism can also found to be diagnosed with intellectual disabilities (IQ scores below 70) at a rate of 68%. Learning disabilities are also common, with specific impairments in executive function. Anxiety disorders are among the most common to be additionally diagnosed in a child with autism with rates ranging from 7-84%. Autism is also known to coexist, with a rate of 11-39%, with seizure disorders and up to 9% with tic disorders. Approximately 50-70% also have issues with sleep disturbances or sleep disorders. This population of children is also at a higher risk for developing mood disorders and symptoms of attention-deficit/hyperactivity disorder.
Causes
The cause of autism disorder is still relatively unknown. However, there is increasing amounts of research that has found there to be some genetic components to the disorder. Family studies have shown that there is a 3-5% chance of siblings also being diagnosed with the disorder and an even higher rate for twins, with a rate as high as 65%.
A number of biological and environmental causes have also been associated with autism but none of them are definitive to the disorder. These include genetic disorders, prenatal exposure to infections (rubella), prenatal exposure to teratogens (drugs, medications), and brain abnormalities.
References
Alberta Learning. (2003). Teaching students with autism spectrum disorders. Retrieved from http://education.alberta.ca/admin/supportingstudent/diverselearning/autism.aspx
Hyman, S.L. & Towbin, K.E. (2009). Autism spectrum disorders. In M.L. Batshaw, L. Pellegrino, & N.J. Roizen (Eds.), Children with disabilities (pp.325-344). Baltimore, MD:Paul H. Brooks Publishing
Kerig, P.K. & Wenar, C. (2006). Infancy: Disorders in the autistic spectrum. In Developmental psychopathology: From infancy through adolescence (5th ed.) (pp.131-158). New York: McGraw-Hill.
Hyman, S.L. & Towbin, K.E. (2009). Autism spectrum disorders. In M.L. Batshaw, L. Pellegrino, & N.J. Roizen (Eds.), Children with disabilities (pp.325-344). Baltimore, MD:Paul H. Brooks Publishing
Kerig, P.K. & Wenar, C. (2006). Infancy: Disorders in the autistic spectrum. In Developmental psychopathology: From infancy through adolescence (5th ed.) (pp.131-158). New York: McGraw-Hill.