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Course and Prevalence of Autism Spectrum Disorders

Prevalence of Autism Spectrum Disorders

Current estimates of the rates of Autism Spectrum Disorders suggest that these conditions affect as much as 0.65% of the general population, or about 1 in every 150 people, which is quite substantial [ref]. The rates of Autistic Disorder are at least 0.13% of the population, Asperger's Disorder affects at least 0.03%, and Atypical Autism (PDD-NOS) can be found in about 0.21% of the population [ref].

Autistic Disorder is about 4 times more common in males than in females. In cases where mental retardation is more pronounced, the difference in rates between men and women diminishes to a ratio of about 2:1, whereas in high-functioning groups of people with Autistic Disorder, male predominance is even more pronounced, that is, up to 8 times more common [ref].

Associated Conditions (Comorbidity) of Autism Spectrum Disorders

Among individuals with Autistic Disorder, about 30% have normal intelligence, 30% have mild-to-moderate mental retardation, and 40% have serious-to-profound retardation [ref].

Between 6-10% of individuals with Autistic Disorder have an identifiable medical condition that can explain the occurrence of their condition. Fragile X Syndrome and Tuberous Sclerosis are two of the most common genetic conditions known to lead to Autistic Disorder [ref].

Other general medical conditions known to occur with some frequency in Autism Spectrum Disorders include Epilepsy (more common in cases with severe mental retardation), Cerebral Palsy, Phenylketonuria, Neurofibromatosis, Down syndrome, congenital Rubella, and visual and hearing problems [ref].

About 70% of children with Autism Spectrum Disorders will suffer from other psychiatric conditions [ref]. Over 40% will have Anxiety Disorders (about 30% will have Social Phobia, 13% will have Generalized Anxiety Disorder, 10% will have Panic Disorder, and 8% will have Obsessive-Compulsive Disorder (OCD) [ref]. Attention-Deficit/ Hyperactivity Disorder (ADHD) will occur in close to 30% of children with Autism Spectrum Disorders, as will Oppositional Defiant Disorder [ref].

Prognosis of Autism Spectrum Disorders

There is no known cure for Autism Spectrum Disorders, though various kinds of treatments are recommended. Studies have shown that between 3% and 25% of children eventually lose their Autism Spectrum Disorder diagnosis and enter the normal range of cognitive, adaptive and social skills [ref].

Recovery is more likely among individuals with relatively high intelligence and better language and motor skills, as well as those who received an earlier diagnosis and treatment, or who have a diagnosis of PDD-NOS [ref]. Recovery is less likely in individuals who have seizures, mental retardation, and other genetic syndromes [ref].

Unfortunately, most individuals with Autism Spectrum Disorders face a very difficult life with a lack of social supports, meaningful relationships, employment opportunities, or the ability for self-determination [ref]. Many individuals with this condition will have difficulties living autonomously even in adulthood.


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