Autism Spectrum Disorder (Grove, 2019) – Is Asperger syndrome genetic?

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Additional Information

What is Asperger syndrome? (Part 1 of Is Asperger syndrome genetic?)

Autism Spectrum Disorder (ASD) is the name of autism used from 2013 onwards in the 5th edition of the Diagnostic and Statistical Manual of the American Psychiatric Association (DSM-5). Previous editions of the DSM, and the 10th edition of the World Health Organization’s International Classification of Diseases (ICD-10), use the term Pervasive Developmental Disorder (or PDD). Now, PDD and other forms of autism, such as the term Asperger syndrome, are all classified under ASD. 

Asperger syndrome (AS) is a variant of autism and is classified as a disorder of neural and mental development, affecting the patient’s mental health. It differs from other forms of autism primarily in that there is usually unimpaired speech development and no reduction in intelligence. 

Characteristics of children with Asperger syndrome include difficulties in social interaction and communication skills as well as differences in perception and stimulus processing (including in particular sensory hypersensitivity and hyposensitivity and difficulties in stimulus filtering) and often extraordinary interests and talents. 

Is Asperger Syndrome Genetic?

The causes of Asperger syndrome (and of the entire autism spectrum) lie in developmental deviations in the development and growth of the brain.

Brain activity comparing the brain of someone with Asperger syndrome and a brain of someone who is neurotypical
A comparison of the activity between (Temple Grandin’s) Asperger brain and a neurotypical brain. Dr. Walter Schneider from Pittsburgh University. Attribution-Share Alike 4.0 International

The genetic causes of the full range of the autism spectrum have proven to be extremely diverse and highly complex. Changes in over 1,000 genes have been reported to lead to an increased risk of ASD, but autism research has not been able to confirm a large number of these associations through genetic studies. Many of the genes associated with ASD are involved in the development of the brain. Some twin studies show that autism is a highly heritable condition and, as of 2009, known genetic syndromes, mutations, and metabolic diseases account for up to 20% of autism cases. In a 2020 review, it was also argued that there was not yet sufficient evidence of genes specific to the autism spectrum. 

It is generally believed that the immense combination possibilities of many genetic variations are the cause of the great diversity and breadth of the autism spectrum, including Asperger syndrome. Risk factors may also include environmental factors separate from genetic disposition. 

Submicroscopic changes in chromosomes also play a key role in autism, namely copy number variations. Chromosomal abnormalities most often happen in the form of gene duplication or gene deletion that occur when the mother’s eggs or the father’s sperm cells (meiosis) are formed.

However, if a child receives such a deviation from one of the parents, it can run in families, with a 50% probability. Thus, it is possible that an abnormality that contributes to autism occurs only once in a child and is not passed on, or it may affect several family members in different generations. The impact (penetrance and expressiveness) of such a genetic abnormality can also vary greatly from person to person.

Epidemiology (Part 3 of Is Asperger syndrome genetic?)

Especially since the reclassification of Asperger syndrome as part of ASD in 2013, there is not a good estimate of the prevalence of Asperger syndrome. According to a 2009 study, the prevalence of Asperger syndrome in children was estimated at 0.02% – 0.03%. At that time, Asperger syndrome was diagnosed more often in boys than girls. In 2020, the CDC reports that 1 in 54 have been identified with autism spectrum disorder and an ASD diagnosis is more than 4 times more common in boys than in girls. Some scientists such as the U.K-based scientist, Simon Baron-Cohen, have tried to explain this observation through years of research.

Symptoms and Characteristics (Part 4 of Is Asperger syndrome genetic?)

While the first signs of other forms of autism appear in the first months of life, Asperger syndrome usually does not become apparent until after the age of three. General characteristics are: a qualitative impairment of social communication and interaction, lack of empathy, sensory, motor and linguistic peculiarities, and pronounced narrow interests.

Motor skills and social behavior (Part 4.1 of Is Asperger syndrome genetic?)

Motor skills

Frequently, motor peculiarities occur in Asperger syndrome, which are normally absent in other autism spectrum conditions. These include awkward movements, clumsiness, and gross and fine motor coordination disorders.

Social behavior

Like other autistic children, children with Asperger syndrome make little and only fleeting eye contact. In everyday life, a lack of empathy and a lack of understanding for interpersonal feelings is conspicuous. Children with Asperger syndrome are often socially isolated and corner easily due to their characteristics. 

People with Asperger syndrome, even if they want to make contact with others, are often perceived as formal, unfeeling, fearful, shy, evasive, dismissive or disinterested due to their frequently averted gaze and closed body language, which often causes contact to fail.

A toddler. Most children with Asperger's aren't diagnosed until later.
Most children with Asperger syndrome are not diagnosed until adolescence. Pixabay.com

Language, special interests, intelligence, and ritualized actions (Part 4.2 of Is Asperger syndrome genetic?)

Language

In most autism cases, language skills are delayed. However, children with Asperger syndrome often develop a grammatically and stylistically superior language. The tone of voice is often monotonous and does not support, for example, the difference between serious and humorous expressions. Often, people with autism speak with an inappropriate or unusual rate and volume. Jerky, jerky speech also occurs. 

Many children and adults with Asperger syndrome tend to talk incessantly and lengthily, usually about a specific topic. Further characteristics are a very detail-oriented narrative style with difficulties in distinguishing the essential from the unessential, abrupt changes of topic that are incomprehensible to the listener, taking literally pictorial phrases and answering rhetorical questions.

Special Interests

People with Asperger syndrome develop a great interest in social contacts, but do not know how to implement them. Difficulties in recognizing the body language and facial expressions of others play a role and are often understood as a lack of empathy. Typically, however, they have other special interests that seem unusual in the matter or in their intensity. These interests often lie in technical or scientific fields such as computer science, mathematics, physics, biology or astronomy. Others are passionate about music or the memorization of various facts. 

Intelligence

In contrast to some other forms of autism, intelligence is often normal in people with Asperger syndrome. Asperger children are occasionally observed to have premature reading (hyperlexia).

Ritualized actions

People with Asperger are often fixated on keeping their external environment and daily routines as consistent as possible. Sudden changes can overwhelm them or make them very nervous.

Autism awareness puzzle
Autism awareness puzzle. Pixabay.com

Diagnosis (Part 5 of Is Asperger syndrome genetic?)

It’s common for Asperger syndrome to be diagnosed much later than more severe forms of autism. While most autistic children are diagnosed before the age of 2, a 2008 CDC report, the average age of Asperger diagnosis was 6 years. A 2007 British study reported further delay in Asperger diagnosis – averaging around age 11. Children with Asperger syndrome are at the high functioning autism level and do not demonstrate language or intellectual delays. 

The current Diagnostic and Statistical Manual of Mental Disorders (DSM-5), published by the American Psychiatric Association, removed Asperger syndrome as a single neurodevelopmental disorder. It is now included in the autism spectrum disorders category; similar to childhood disintegrative disorder and other pervasive developmental disorder (not otherwise specified). 

Researchers have recently started to assume that these are not different diseases, but a seamless continuum of very mild to severe forms of developmental disorder that begin in early childhood. A distinction is made between deficits in two categories: Firstly, social interaction and communication is disturbed (for example, eye contact, ability to converse or build relationships are weak). Secondly, repetitive behavior and fixed interests and behaviors are characteristics of autistic disorders. 

The previous DSM, DSM-IV, in 2000 included the following qualitative diagnostic criteria for Asperger syndrome, some genetic variants.

  1. Qualitative impairment of social interaction, manifesting itself in at least two of the following areas:
    1. Noticeable impairment of several non-verbal behaviors that control social interaction, such as eye contact, facial expressions, posture and gestures
    2. Relationships with peers are not developed, or not according to the level of development
    3. Lack of spontaneous turning to others to share joy, interest or pride in an achievement (for example, affected children do not tend to show things they are interested in to other people)
    4. Lack of social or emotional reciprocity
  2. Limited repetitive and stereotypical patterns of behavior, interest and activity that manifest themselves in at least one of the following characteristics:
    1. Extensive engagement with one or more stereotypical and limited patterns of interest that are abnormal in intensity or subject matter
    2. Obviously rigid adherence to certain non-functional routines or rituals
    3. Stereotypical and repetitive motor habits (for example, hand or finger movements or complex movements of the whole body)
    4. Persistent occupation with object parts
  3. The disorder causes a clinically significant impairment in social, professional or other important areas
  4. There is no clinically significant general speech delay (e.g. use of single words in the second year of life, communicative sentences in the third year of life)
  5. There is no clinically significant delay in the development of cognition, self-help skills and adaptive behavior (except social interaction) and – in childhood – curiosity about the environment
  6. The disorder does not meet the criteria of any other profound developmental disorder or schizophrenia

Possible side effects (Part 6 of Is Asperger syndrome genetic?)

Sometimes Asperger syndrome also occurs together with other mental disorders:

  • One of the most frequent concomitant symptoms is depression, which is usually caused by impairments in private and professional life
  • Some people with Asperger syndrome also meet the criteria for an obsessive-compulsive disorder or an obsessive personality disorder
  • If concentration difficulties are present, Asperger syndrome is easily confused with attention deficit hyperactivity disorder, ADHD. Both disorders can, however, also occur together
  • Occasionally a common occurrence of Asperger syndrome and Tourette’s syndrome has been described
  • Sometimes a common occurrence of Asperger syndrome and anorexia nervosa (anorexia nervosa) is also observed

Treatment (Part 7 of Is Asperger syndrome genetic?)

Not every diagnosis of Asperger syndrome leads to its classification as a disease that should be considered or even treated. There are also no therapies that address the syndrome directly. Symptomatic therapy based on cognitive behavioral therapy approaches and social skills training is possible. 

Asperger syndrome clipboard
Treatment for Asperger syndrome includes behavioral therapy and medications to treat accompanying conditions. Nick Youngson Alpha Stock Images CC BY-SA 3.0

If symptoms such as pronounced hyperactivity and agitation, aggressive behavior, sleep disorders or depressive moods are added, medication is also used. 

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