The Autism Spectrum
Autism spectrum disorder (ASD), commonly referred to simply as autism, is a neurological and developmental variation that affects learning, communication and social interaction. Autism can be found across all racial, ethnic and social groups and is associated with a wide range of behaviors and characteristics which may include intense focus on a specific subject; unconventional means of learning and problem-solving; a strong need for routine and consistency; repetitive movement or self-stimulation, such as rocking or humming; difficulty with social interpretation and expression; and an under- or over-sensitivity to sensory experiences like sound, light and touch. Each individual on the autism spectrum is different, with a unique set of characteristics and behaviors that may change depending on stress or anxiety levels and sensory stimulation. Individuals on the far end of the autism spectrum may be non-verbal, harm themselves or depend heavily on support from family and professionals, while other adults with autism may live and work independently. The exact cause of autism is unknown, though genetics and environmental conditions are thought to be possible factors.
Prior to May 2013, diagnosticians separated the varying degrees of autism spectrum disorder into subsets that included autism disorder, Asperger's syndrome, pervasive development disorder not otherwise specified, Rett syndrome and childhood disintegrative disorder. Since these subsets are differentiated solely by behaviors, they were often difficult to determine. In an effort to provide more clarity and diagnostic precision, the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (the manual published by the American Psychiatric Association and used as the standard for classifying mental disorders), released in May 2013, eliminated these subsets and instead breaks down positions on the autism spectrum by levels (ex. Autism Spectrum Disorder, Level 1, Level 2, or Level 3).
As of March 2013, the Centers for Disease Control and Prevention estimate that one in 50 children are identified with autism spectrum disorder, compared to about 1 in 155 in 2002 and 1 in 88 in 2012. However, this rapid increase may be attributable more to greater awareness and more frequent diagnosis than to an actual increase in the incidence rate. Diagnosing autism accurately is not easy and, according to the Diagnostic and Statistical Manual of Mental Disorders, there are more than 600 different symptom combinations that meet the minimum criteria for diagnosing autism disorder--just one of the formerly used subsets of autism spectrum disorder. The Autism Diagnostic Observation Schedule (ASOD) and the Autism Diagnostic Interview, Revised (ADI-R) are the standard assessment tools used for diagnosis, but many other screening tests exist. Administering assessments that are accurate and comprehensive is a difficult task, as traits associated with autism exist on a continuum and may be observed among those not clinically diagnosed with a related disorder.
Though there is little conclusive neurological research on autism and other neurological disorders, scientists have found variations in the size, function and development of various parts of the brain, such as the cerebellum, the hippocampus and the amygdala. The amygdala (two almond-shaped structures located in the temporal lobes of the brain) are used in processing emotions, social interaction, experiencing fear and exercising facial recognition. Some individuals with autism, anxiety disorders and other neurological disorders have been found to have overly large or small amygdala. There are also scientists who believe that autism may be linked to poor fiber tract connections to key areas in the brain. The range of physical and behavioral characteristics exhibited by individuals with autism, and flaws in scientific tests like neuroimaging (brain scans), make it difficult to prove these theories conclusively. Individuals not on the autism spectrum also exhibit variations in size and development of these areas of the brain. There is no one "typical" human brain that can be used as a baseline.
Caption: Paula on her computer.
Credit: Neurotypical.
Sources:
» Armstrong, Thomas. The Power of Neurodiversity: Unleashing the Advantages of Your Differently Wired Brain. Cambridge: Da Capo Lifelong, 2011.
» Autism Network International. "Don't Mourn For Us."
» Autism Research Institute. "DSM-V: What Changes May Mean."
» Autism Society.
» Autistic Self Advocacy Network.
» Carey, Benedict. "Diagnoses of Autism on the Rise, Report Says." The New York Times, March 29, 2012.
» Centers for Disease Control and Prevention.
» Gever, John. "Amygdala Enlarged in Young Autistic Children." MedPage Today, May 4, 2009.
» Grandin, Temple. "The World Needs People with Asperger's Syndrome" The DANA Foundation, October 1, 2002.
» Grandin, Temple and Richard Panek. The Autistic Brain: Thinking Across the Spectrum. New York: Houghton Mifflin Harcourt, 2013.
» Hamilton, Jon. "What's Different About the Brains of People with Autism?" NPR, June 4, 2012.
» Jaarsma, Pier and Stellan Welin. "Autism as a Natural Human Variation: Reflections on the Claims of the Neurodiversity Movement." Health Care Analysis, March 2012.
» National Institute of Neurological Disorders and Stroke.
» PBS. "What is Autism?"
» PBS. "History of Autism Blame."
» PBS. "What Is Autism?"
» Salahi, Lara. "10 Myths About Autism." ABC News, October 23, 2008.
» Science Daily. "In Autism, Age at Diagnosis Depends On Specific Symptoms."