There have been many theories about Asperger's causes that range from genetic and viral factors to an impairment in brain functioning. Asperger's syndrome was first studied by Dr. Leo Kanner from the United States and Dr. Hans Asperger in Austria. The doctors noted the connection between the symptoms of what would later be called Asperger's syndrome and autism. It was Dr. Lorna Wing who gave the disorder its name in her 1981 research paper “Asperger’s Syndrome: A clinical account".
Much of the research into Asperger's causes is focused on people with autism and then extrapolated to Asperger's which is an autism spectrum disorder.
Asperger’s Causes: Genetics
A single gene or group of genes for Asperger's have not been located but there has been some fascinating genetics research.
British doctors Michael Rutter and Susan Folstein conducted the monumental study "Infantile Autism: a genetic study of 21 twins" in 1977 that was published in the Journal of Child Psychology and Psychiatry. Ten of the twins were fraternal while eleven were identical. They noted that if one of the fraternal twins was diagnosed with Asperger’s then the other sibling did not have an autism diagnosis. However when it came to the identical twins over 90% of both twins displayed autistic symptoms.
Dr. John N. Constantino from the Department of Psychiatry at Washington University School of Medicine also looked at possible genetic causes in his 2003 paper "Autistic traits in the general population: a twin study".
During this study 788 autistic twins between the ages of seven and fifteen were selected. One of the parents of each set completed a Social Responsiveness Scale on both twins. They evaluated these results using a structural equation modeling method. According to the Social Responsiveness scale autistic traits between siblings were moderately high and “heritable” or genetic.
Andrea Ciaranello of Harvard University and Roland Ciaranello from the Stanford School of Medicine conducted a 1995 study entitled: "The neurobiology of infantile autism". Published in the Annual Review of Neuroscience, it noted a marked increase between children who were born during the Rubella pandemic of 1964 and their rate of autism. Rubella is a viral infection. It was observed that the autism rate surpassed 7%. Prior to the pandemic the rate of autism was less than .01%. To add perspective, autism rates are presently 1%. This significant increase in autism cases of children born during the Rubella pandemic remains a very prolific argument for viruses being a potential cause of Asperger’s syndrome.
When attempting to find potential autism or Asperger's causes, prenatal stress has been observed as a potential factor. A 2005 study by researchers from the Ohio State University Medical Center Department of Neurology entitled "Timing of prenatal stressors and autism" provided very convincing evidence that prenatal stress could potentially affect an autism spectrum diagnosis.
The scientists gathered four weeks of data from schools and clinics of mothers of autistic and Down syndrome children. They observed that there was an increased level of stress in mothers of autistic children between the 21st and 32nd week of pregnancy.
The final example of a potential cause of Asperger’s syndrome is brain functioning. Researchers at the Carnegie Mellon’s Center for Cognitive Brain Imaging have been studying cognitive and brain activity characteristics of high functioning people with autism since 2005. One of their many discoveries is frontal-parietal under connectivity in people with autism. These regions are involved in higher cognitive functions although the under connectivity in autistic people is not limited to cognition.
The studies are revealing widespread neural connectivity abnormalities in people with autism and to determine the effects of these scientists are studying the abnormalities in four different areas – visuospatial processing, social cognition, language comprehension, and executive functioning.
While it may be unclear what causes Asperger’s syndrome it is clear that it is not brought on by “bad mothering”, which was a previous idea. Families and caregivers of individuals who have Asperger’s syndrome can assist in helping scientists to find a cause by submitting statistical data in surveys that appear from time to time.
NB: The content of this article is for information purposes only and is not intended to replace sound medical advice and opinion.
Dr. Michael Rutter, Dr. Susan Folstein Infantile autism: a genetic study of 21 twin pairs https://sfari.org/commentaries/-/asset_publisher/lVf7/content/1977-paper-on-the-first-autism-twin-study-commentary-by-angelica-ronald-and-robert-plomin?redirect=%2Fcommentaries
JN Constantino, Todd RD Autistic Traits in the general population: a twin study https://www.ncbi.nlm.nih.gov/pubmed/12742874?dopt=Abstract
Andrea Ciaranello, Roland Ciaranello The Neurobiology of Infantile Autism https://nro.sagepub.com/content/1/6/361.abstract
Beversdorf DQ, Manning SE, Hillier A, Anderson SL, Nordgren RE, Walters SE, Nagaraja HN, Cooley WC, Gaelic SE, Bauman ML Timing of Prenatal Stressors and autism https://aarr.stanford.edu/
Marcel Just, Rajesh Kumar Kana, Vladimir Cherkassky, Tim Keller, Robert Mason https://www.ccbi.cmu.edu/projects_autism.html