Autism spectrum disorder (ASD) and autism are both general terms for a group of complex disorders of brain development. These disorders are characterized, in varying degrees, by difficulties in social interaction, verbal and nonverbal communication and repetitive behaviors.
ASD can be associated with intellectual disability, difficulties in motor coordination and attention and physical health issues such as sleep and gastrointestinal disturbances. Some persons with ASD excel in visual skills, music, math and art.
Autism appears to have its roots in very early brain development. However, the most obvious signs of autism and symptoms of autism tend to emerge between 2 and 3 years of age. By the age of three, children with ASD show difficulties in three main areas:
Over the last five years, scientists have identified a number of rare gene changes, or mutations, associated with autism. A small number of these are sufficient to cause autism by themselves. Most cases of autism, however, appear to be caused by a combination of autism risk genes and environmental factors influencing early brain development.
In the presence of a genetic predisposition to autism, a number of nongenetic, or “environmental,” stresses appear to further increase a child’s risk. The clearest evidence of these autism risk factors involves events before and during birth. They include advanced parental age at time of conception (both mom and dad), maternal illness during pregnancy and certain difficulties during birth, particularly those involving periods of oxygen deprivation to the baby’s brain. It is important to keep in mind that these factors, by themselves, do not cause autism. Rather, in combination with genetic risk factors, they appear to modestly increase risk.
About 1 in 50 American children are on the autism spectrum–a ten-fold increase in prevalence in 40 years. Careful research shows that this increase is only partly explained by improved diagnosis and awareness. Studies also show that autism is four to five times more common among boys than girls. An estimated 1 out of 54 boys and 1 in 252 girls are diagnosed with autism in the United States.
ASD affects over 2 million individuals in the U.S. and tens of millions worldwide. Moreover, government autism statistics suggest that prevalence rates have increased 10 to 17 percent annually in recent years.
Here are the approximate U.S. demographics of autistic children:
Age Mild Moderate Severe
Under 5 years 200,000 132,000 68,000
5 to 9 years 200,000 132,000 68,000
10 to 14 years 200,000 132,000 68,000
80% of these are male.
Autism Sensory Characteristics
An important aspect of ASD is dysfunction or difficulty in the processing of sensory information. The dysfunction is believed to occur within the central nervous system (CNS). This results in distorted perceptions of the world around them along with unusual behavior as the child tries to compensate. The distortions are different for each child. An individual may be over-sensitive (hyper) to some senses while being under-sensitive (hypo) to others. To many autistic children, the senses of touch and smell are more reliable. They touch and smell everything and may constantly tap everything to “see” the boundaries of their environment. Most ASD children are “monotropic”, meaning they can only utilize one sense at a time. Most people are “polytropic” and can see, hear, feel, smell and talk all at the same time.
Significantly, a “normal” environment may cause the child to experience much discomfort (too noisy, too much activity, boring, etc.) and a lot of attention is rightly given to modifying their surroundings accordingly.