Definition of Autism Spectrum Disorder
The Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-V), (American Psychiatric Association, 2013) is a handbook used by professionals around the world to diagnose mental disorders. The DSM-V contains descriptions, symptoms, and other criteria (such as how many of these symptoms must be present) to diagnose a disorder.
The DSM-V classifies Autism Spectrum Disorder (ASD) as a type of neurodevelopmental disorder characterised by difficulties in two domains:
- Social communication and social interaction,
- Restricted, repetitive patterns of behaviour, interests or activities.
Causes of ASD
In 1943, Austrian American psychiatrist, Dr Leo Kanner, described “early infantile autism” as a distinct clinical syndrome. However, until the late 1970s and 1980s, ASD was considered a psychological disorder that was caused by poor parenting, specifically the role of the mother. Dr. Kanner coined the phrase “refrigerator mother” to describe the notion that ASD was caused by the mother being cold, distant, unresponsive, and rejecting of her child. However, we now know that it is not a psychological disorder and not caused by poor parenting it is a neurodevelopmental disorder.
The entry of autism and Asperger syndrome (AS) into the history of psychopathology was marked by extraordinary coincidences. Both disorders were first described by Kanner (1943) and Asperger (1944), respectively. Both were Austrian-born physicians and, though unaware of each other’s writings, both used the term “autistic” to describe a unique group of children who shared features of impaired social interaction and restricted, repetitive behaviors and interests.
AS had already been described in 1981 by Lorna Wing, who first proposed the term to refer to a special subgroup of children who, according to Asperger’s original description, were characterized by: social isolation and lack of reciprocity in social interactions; normal or precocious language acquisition, with above-average linguistic skills but subtle abnormalities of verbal and non-verbal communication (e.g., atypical syntax, pedantic vocabulary and absent or stereotyped prosody); a narrow focus of interests, often restricted to unpragmatic and highly original themes; overachievement in specific cognitive domains; and motor clumsiness (Wing, 1981).
The exact cause of ASD is currently unknown. The DSM-5 states that there is no exact cause of ASD, which is not surprising given the diversity of its unique presentation in each individual in terms of symptoms, skills, and severity. Instead, it’s rather the interaction between the risk factors that may contribute to its development.
These may include:
- Genetic factors – there is no single gene causing ASD, instead, over hundreds of different genes are involved. Certain genes inherited from the parent can make the child vulnerable to developing ASD. Also, having a parent, sibling, uncle, or aunt with ASD also increases the likelihood of the child having ASD.
- Neurobiological factors – abnormalities in the genetic code may result in changes in the way the brain develops and works.
- Environmental factors – parental health (e.g. infections and diseases the mother might have had during pregnancy); maternal use of medications, drugs, and toxic chemicals during pregnancy, low birth weight, childhood illness, food intolerance, and reactions to pollutants may contribute to the child developing ASD.
It is important to remember that there is insufficient evidence to implicate any one environmental factor to the development of ASD; instead, they increase the risk of the development of ASD in children who are genetically predisposed.
Important Note: Vaccines do not cause Autism Spectrum Disorder
An article by Wakefield et al. (1998) proposed a link between the Measles-Mumps – Rubella (MMR) vaccine, colitis and the development of ASD in 12 children.
By 2004, 11 of the contributing authors retracted their interpretation that there was a causal link between the MMR vaccine and ASD in their article (Murch et al., 2004). Furthermore, a formal investigation by the British Medical Council in 2010 also found that the study by Wakefield et.al. (1998) had not been approved by the bioethics committee. Further investigation revealed that the facts about the children’s histories that were part of the study had been altered and none of their medical records could be reconciled with the descriptions in the published paper. Based on these findings, Wakefield’s licence to practice medicine was revoked.
Since then, several scientific studies have consistently and effectively ruled out receiving vaccines and developing ASD throughout the world. For example, in an article by Taylor et al. (2014), they completed a meta-analysis, combining the results of 10 studies on over 1.2 million children and found no causal link between vaccines and ASD.
Symptoms of ASD
Domain 1 – Persistent difficulties in social communication and social interaction as evidenced by the presence of all of the following symptoms, across multiple contexts, currently or historically:
- Difficulty with social-emotional reciprocity: this can range from abnormal initiation of social interactions and difficulty with normal back-and-forth conversation; to reduced sharing of interests, emotions, or thoughts; to a complete lack of initiating or responding to social interactions.
- Difficulties with nonverbal communication: this can range from poorly integrating nonverbal communication like body language with verbal communication; to abnormalities in eye contact and body language or difficulty understanding and using gestures; to a total lack of facial expressions and nonverbal communication.
- Deficits in developing, maintaining, and understanding relationships: this can range from difficulties adjusting behaviour to suit various social contexts; to difficulties making friends; to a complete lack of interest in peers.
Domain 2 – Restricted, repetitive patterns of behaviour, interests, or activities, as evidenced by the presence of at least two of the following symptoms, currently or historically:
- Stereotyped or repetitive movements, use of objects, or speech, such as lining up toys or flipping objects, repeating the words of others back to them, or repeating idiosyncratic phrases.
- Insistence on sameness, inflexible adherence to routines, or ritualised patterns of verbal and nonverbal behaviour, such as extreme distress at small changes, difficulties with transitioning between places or activities, rigid thinking patterns, or greeting rituals.
- Highly restricted, fixated interests that are abnormal in intensity or focus, such as strong attachment to or preoccupation with unusual objects.
- Hyperreactivity or hyporeactivity to sensory input or unusual interest in sensory aspects of the environment, such as apparent indifference to pain or temperature, adverse response to specific sounds or textures, excessive smelling or touching of objects, or visual fascination with lights or movement.
For an individual to be diagnosed with ASD, symptoms must be present at an early age, but may not fully manifest until social demands exceed the ability of the individual to deal with them. The symptoms should cause significant impairment on social, occupational or other important areas and not be better explained by intellectual disability or global development decay.
Presence of other conditions
If an individual is diagnosed with ASD, the medical professional may also specify if it is:
- With or without accompanying intellectual impairment.
- With or without accompanying language impairment.
- Associated with a known medical or genetic condition or environmental factor.
- Associated with another neurodevelopmental, mental, or behavioural disorder.
- With catatonia.
American Psychiatric Association (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.). Arlington, VA: American Psychiatric Association.
Murch, S., Anthony, A., Casson, D., Malik, M., Berelowitz, M., Dhillon A., et al. (2004). Retraction of an interpretation, Lancet, 363 (9411), p. 750.
Taylor, L.E., Swerdfeger, A.L. & Eslick, (2014). Vaccines are not associated with autism: An evidence-based meta-analysis of case-control and cohort studies. Vaccine, 32(29), p. 3623–3629.
Wakefield, A. J., Murch, S. H., Anthony, A., Linnell, J., Casson D.M., Malik, M. Berelowitz, M., Dhillon, A.P., Thomson, M.A., Harvey, Pl, et al. (1998). Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children [retraction published in Lancet. 2010; 375(9713): 445]. Lancet, 35(9103), p. 637–641.
Wing, Lorna. (1981). Asperger syndrome?: A clinical account. Psychological Medicine, 11(1), 115-129.
Kanner, L. (1943). Autistic disturbances of affective contact. Nervous child, 2(3), 217-250.