What is Autism Spectrum Disorder?
Autism Spectrum Disorder (ASD) is classified as a neurodevelopmental disorder (an impairment in brain development that affects learning ability, emotion, and memory) in the most recent edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). This new categorization encompasses several disorders that were previously diagnosed under the umbrella of “Pervasive Developmental Disorders.” They included Autistic Disorder (autism), Asperger’s Disorder, Rett’s Disorder, Childhood Disintegrative Disorder, and Pervasive Developmental Disorder not otherwise specified. Based on clinical research and scientific consensus, these five disorders are better conceptualized as one condition with varying levels of symptom severity.
Autism Spectrum Disorder is characterized by pervasive difficulties in social interaction, communication patterns, and impairment in behaviors, interests, and activities. ASD varies greatly depending on the age and developmental level of the individual. Symptoms range from mild to severe based on the level of support needed. A diagnosis of Autism Spectrum Disorder is typically diagnosed in the first 3 years of life.
Each individual “on the spectrum” is distinctive. Asperger’s Disorder was conceptualized as a less severe form of Autistic Disorder. Those who were considered to have Asperger’s experienced less severe symptoms and an absence of language delays. While Rett’s Disorder and Childhood Disintegrative Disorder are considerably more rare and often involve physical impairments, they share many similar features with Autism and Asperger’s. Now, they are all thought of as different points on the continuum of a single disorder spectrum.
Prevalence of Autism Spectrum Disorder
The prevalence of Autism Spectrum Disorder (ASD) has increased in recent decades. In 2007, the prevalence of parent-reported ASD among children aged 6-17 was a little over 1%. That translated to about 1 in 88 children.
Recent data from the National Survey of Children’s Health (NSCH) conducted in 2011-2012, however, shows that parent-reported ASD increased to 2%.
That translates to about 1 in 50 children.
The greatest increase was seen in boys and adolescents aged 14-17.
Many researchers in the field attribute the increase to cases of Autism Spectrum Disorder that had previously gone undiagnosed. More parents and doctors are aware of the disorder and its warning signs now than in the past.
Boys are about 4-5 times more likely to be diagnosed with an autism spectrum disorder than girls.
Based on reports conducted by the Centers for Disease Control and Prevention, prevalence rates for Autism Spectrum Disorder varied among ethnicity. Prevalence rates were 12 in 1000 for white children, 10 in 1000 for black children, and 8 in 1000 for Hispanic children.
What are the Symptoms of Autism Spectrum Disorder?
The symptoms of Autism Spectrum Disorder typically indicate impairment in three areas: social skills, verbal and non-verbal communication, and restricted and repetitive behaviors. These impairments are unique to each individual. Symptoms can be blatant or barely noticeable.
Related Spectrum Disorders
Rett Syndrome is a very rare neurodevelopmental disorder that is characterized primarily by developmental regression. Rett syndrome is found almost exclusively in females. It affects only 1 in 10 thousand to 22 thousand girls.
Generally, individuals with Rett syndrome develop normally in the first 6-18 months of life. This is followed by a period of time up to around 48 months that is marked by a slowing in development. This developmental regression includes a decline in brain and head growth, loss of previously acquired hand skills, loss of social interaction and engagement, and excessive impairment in language development.
Rett syndrome has its onset before the age of 4 and is typically diagnosed within the first 2 years of life. Rett syndrome is a lifelong disorder in which the loss of skills and social impairment is persistent and progressive.
Childhood Disintegrative Disorder
Childhood Disintegrative Disorder (CDD) is even more rare than Rett syndrome. CDD affects only 1 or 2 children out of 100,000. Because of its rare occurrence, researchers find it difficult to study the disorder.
Childhood Disintegrative Disorder is characterized by a significant regression in different areas of functioning that follow a period of apparently normal development. The average age of onset is between 3 and 4 years. Prior to onset, children with CDD experience normal development in communication and social skills. The extended period of normal development prior to the CDD’s onset helps distinguish it from Rett syndrome. CDD has been found to affect boys more than girls.
Children with CDD experience a significant and pervasive loss of previously acquired social, communication, and motor skills. The course of CDD is usually lifelong. Typically, the loss of skills hits a plateau. Some improvement may occur. The impairment in communicative, social, and behavioral functioning remains relatively constant.
Warning Signs of Autism Spectrum Disorder
Developmental delays and difficulties in behavior can offer early warning signs for parents who are concerned about their infants and toddlers. Parents who notice the following signs should consult their pediatrician for further evaluation and appropriate referrals.
- Little or no eye contact
- Unresponsive to name being called by 12 months of age
- Inability to point at objects of interest (plane in the sky, car passing by) by 14 months
- Lack of or delay in language
- Rocking body, spinning in circles, flapping hands
- Unusual reactions to sensory stimuli: the way things sound, smell, taste, feel, look
What Causes Autism Spectrum Disorder?
The specific causes of Autism Spectrum Disorder (ASD) are still not completely clear to scientists. Research does show, however, that several factors including difficulties before, during, and after pregnancy, possible abnormalities in early brain development, genetic factors, and environmental influences may all play an important role in ASD’s development.
Identical twin studies show that if one twin has ASD, the other twin will also have the disorder 90% of the time. Research also shows that if a sibling has ASD, other siblings are 35 times more likely to develop the disorder compared to normal risk. With only relatively moderate success thus far, scientists are beginning to identify specific genes that put individuals at risk for developing ASD.
There are also many people with Autism Spectrum Disorder who report no family history of the disorder. Gene mutations (any change to genetic information), then, are likely to play a role in the ASD’s development. While some mutations are inherited, others appear randomly.
While genetic factors affect Autism Spectrum Disorder (ASD), they are not solely responsible for its development. Environmental factors are also thought to influence its onset.
Bad parenting was at one time thought to be a direct cause of Autism Spectrum Disorder. Now, clinical consensus maintains that this is not the case. The majority of researchers and clinicians reject this theory as erroneous and detrimental.
Currently, there is no scientific evidence that definitively links particular environmental toxins, vaccinations, specific dietary practices, or immunologic differences to causing Autism Spectrum Disorder. General consensus endorses some combination of neuropathologic, genetic, and environmental factors that vary between individuals can provide an explanation for ASD’s development.
Treatment for Autism Spectrum Disorder
Currently, there is no known cure for Autism Spectrum Disorder (ASD). There are certain steps that can be taken, however, to ensure a better quality of life for everyone involved. Early interventions including different modalities of intense behavioral therapy and appropriate medical care can greatly reduce symptoms. An open and supportive collaboration between parents, teachers, and providers can facilitate the treatment process.
If you or someone you know is concerned about a child’s development or problematic behaviors, please consult a primary care physician, pediatrician, or mental health professional.