Autism Spectrum Disorder

Introduction[edit | edit source]

Autism Spectrum Disorder is characterized by patterns of delay and deviance in the development of social, communicative, and cognitive skills that arise in the first years of life [1]. Autism Spectrum Disorder (ASD) refers to a group of neurodevelopmental disorders including autism, Asperger's Syndrome (AS) and pervasive developmental disorder-not otherwise specified (PDD-NOS) [2]. It is characterized by deficits in social communication and the presence of restricted interests and repetitive behaviors. ASD can also be defined as a neurobiological disorder predisposed by both genetic and environmental factors affecting the developing brain. [3]

The World Health Organization (WHO) estimates the international prevalence of ASD at 0.76%; however, this only accounts for approximately 16% of the global child population with an increase over the past two decades.

Autism Spectrum Disorder Subcategories

Causes[edit | edit source]

ASD is a neurobiological disorder influenced by both genetic and environmental factors affecting the developing brain. Currently, no single universal cause has been identified but researches are still ongoing to deepen our understanding of potential etiologic mechanisms in ASD [3].

Signs and Symptoms[edit | edit source]

Spectrum means that there is a range of abilities and impairments that occur in people with autism. Children and youth with ADS have different intellectual abilities, therefore their level of support to function needed will also differ. They can have severe intellectual disability, limited or no verbal communication, and very limited adaptive behavior [4] .

Common morbidities associated with ASD include symptoms such as : [2], [5], [6],[7]

  • Attention deficit in nearly 75% of patients
  • Anxiety, irritability
  • Bipolar disorder
  • Depression
  • Tourette Syndrome
  • Insomnia
  • Eating and digestive difficulties
  • Decreased intellectual ability
  • Deficiency in social communication

Risk Factors[edit | edit source]

The following factors have been linked to ASD:

  • Hereditary factors, parental history of psychiatric disorders, pre-term births.
  • Parental age ( advance maternal and paternal age)
  • Maternal history of autoimmune disease such as diabetes, thyroid disease and psoriasis. [3]
  • Prenatal exposure to psychotropic drugs or insecticides like thalidomide and valproic acid. [3]
  • Some of the known genetic disorders such as fragile X, tuberous sclerosis, Down syndrome, Rett syndrome even though they represent a very small amount of overall ASD cases [3].
  • Maternal infection or immune activation during pregnancy
  • Obstetric factors like uterine bleeding, caesarian delivery, low birth weight, preterm delivery, and low Apgar scores are more consistently associated with autism[3].

Early Diagnosis & Diagnosis[edit | edit source]

ASD can be diagnosed by various professionals (pediatricians, psychiatrists, or psychologists), ideally with input from multiple disciplines[8]. Five different autism subtypes are recognized: autism with or without intellectual impairment; autism with or without language impairment; autism accompanying another medical or genetic condition; autism associated with another neurodevelopmental, mental, or behavioral disorder; and autism combined with catatonia [9]. ASD aims to describe autism's early signs by considering five categories of symptoms at onset. These categories include language, social interaction and relationships, stereotyped behavior and activities, motor skills, and regulation[10]. ASDs should be identified as soon as possible to allow intervention to start as quickly as possible too. However, the time of identification varies according to the diversity of autism etiology as well as the varying degrees of associated brain disorder[7]. The most common early signs involve joint attention, eye contact, orienting to verbal call, facial expression, social smile, and deficit or poor quality of movements [10]. Many studies have pointed out the importance of the early identification of ASDs to allow parents and schools to set appropriate measures related to children's behavior and underlying cognitive problems taking into consideration the child's development in all its aspects[7]. It has been demonstrated that early interventions provide the best returns on investment and better results in terms of developmental outcomes and improvement in daily functioning [6].

To identify early symptoms of ASDs and sometimes help make a definitive diagnosis, different approaches/tools are used in different countries. The following ones are used :[10]

  • The CHAT : Checklist for Autism in Toddlers from 18 months to 24 months
  • CARS: Childhood Autism Rating Scale
  • ADOS : Autism Diagnostic Observation Schedule

There are also a number of early intervention programs available that are relatively specifically focused on autism:

  • Screening Tool for Autism in Toddlers and Young Children: STAT
  • For research or a more comprehensive developmental history, caregiver interviews such as the Autism Diagnostic Interview-Revised (ADI-R) or, particularly in the UK, the Diagnostic Instrument for Social Communication Disorders (DISCO), or the computer-generated Developmental, Dimensional, and Diagnostic Interview (3di) are used, with many clinicians relying on informal histories.
  • Assessment of children's symptoms can also be obtained from different scales: Social Responsiveness Scale (SRS), the Social Communication Questionnaire (SCQ), and adaptive scales are also often used as measures of everyday functioning.

Diagnoses based on combined clinician observation and caregiver reports are consistently more reliable than those based on either observation or reports alone. Later diagnoses often occur in presence of co-occurring problems such as anxiety, hyperactivity, or mood disorders that might have triggered the ASD, along with the same factors that play a part in delayed diagnoses in younger children. [8] There is a need for clinical follow-up and reassessments of children diagnosed with ASDs, especially during the preschool years[7].

ASD aims to describe autism's early signs by considering five categories of symptoms at onset. These categories include: a) language, b) social interaction and relationships, c) stereotyped behavior and activities, d) motor skills, and e) regulation.[11]

There are currently no clear existing ASD biomarkers or diagnostic measures. The diagnosis is made based on the completion of descriptive criteria. Clinical genetic testing is recommended as it provides information regarding medical interventions needed. Apart from it, there is no other laboratory genetic testing or other laboratory investigation regularly recommended for every patient with a diagnosis of ASD. Nevertheless, further evaluation may be appropriate for patients with particular findings or risk factors [3].

Treatment[edit | edit source]

Since ASD is usually identified in childhood, different types of therapies have been recommended [9]:

  • Occupational Therapy to concentrate on the adaptive skills needed for the activities of daily living (ADLs).
  • Speech Therapy to improve the child's speech pattern and language understanding.
  • Physical Therapy to improve physical and motor skills. You can read more about the Physiotherapy Management of ASD here.

Children with ASD experience more co-occurring conditions such as insomnia, anxiety, and depression more often than others without it. They also more often have intellectual disability that therefore needs to be addressed as they all impact their condition as well as their rehabilitation [12]. Although adults' behavioral and physical therapy are also recommended or adults, a lot of people with autism have learned coping strategies by the time they reach adulthood. Besides, many adults with milder or moderate forms of the spectrum can lead fairly normal, productive lives [9]

  • Pediatric psychological and social therapy including behavioral and play to help improve their ability to navigate social situations. Different psychosocial interventions targeting both the core symptoms and associated symptoms of ASD such as the Applied behavior analysis (ABA) and Pivotal Response Treatment (PRT) have been developed [13].
  • Education: Children and young adults with ASDs need to be put in mainstream schools where they can discover their abilities. Some of them are very talented and often labeled as twice-exceptional. They have both gifts/talents and disabilities. And like other kids, they have dreams, hopes, and goals to pursue their studies as far as possible and actively contribute to society, and be happy in life even though they understand that their ASD will cause challenges. There is also a need to develop and evaluate academic opportunities, resources, and encouragement that can guide both talent development and special education goals, especially among young adults who will attend competitive colleges [14].
  • Medication such as aripiprazole and risperidone when appropriate, are prescribed for co-morbid depression, anxiety, and impulsivity. They can be prescribed by a child psychiatrist.

Regardless of the significant costs attached to ASD, there are limited treatment options to improve the symptoms associated with ASDs, including both symptoms related to a diagnostic that is considered to be a function of comorbid mental and medical conditions known to exacerbate the severity of presentation criteria [15].

  • Complementary and alternative treatments including chiropractic care, animal therapy, art therapy, mindfulness, or relaxation therapies are also used as treatment options for people with ASD [16]. Special diets and herbal supplements such as Omega-3 supplementation have been relatively well-tolerated and seem to be a safe intervention to consider in children with ASD .[17]

Autism in Low Resource Settings[edit | edit source]

Although the majority of people with ASDs and other developmental disorders live in low- and middle-income countries (LMICs); the knowledge about these conditions is based on research done in high-income countries [20]. Epidemiological studies conducted over the past last half-century suggest that the prevalence of ASDs is increasing around the world, most likely due to improved awareness and reporting, expansion of diagnostic criteria, and enhancement of diagnostic tools [5]. Research about the ASD diagnosis process in LMICs is still limited. Research done in Vietnam and Venezuela demonstrated that the mean age at the first diagnosis was ranging between 30 months and preschool years. The mean age at ASD diagnosis was very similar across LMICs but older than in high-income countries [21]. Studies are required, specifically, epidemiological studies, to define the magnitude of the problem of ASD as well as the characteristics of children with ASD in Africa, especially subSaharan Africa [22]. The scarcity of these studies is due to different barriers included: [21]

  • Lack of knowledge about epidemiological research.
  • Need of contextualization of research tools.
  • Shortage of experienced health professionals
  • Stigma and lack of awareness about ASDs among these professionals (health, social and educational care).

In 2011, Bakare reported that there is a need for epidemiological studies in Africa to help plan and helpfully answer the question of aetiology of ASD [22]. To date, almost all clinical interventions, service developments, research, and policy work for children and adolescents in Sub-Saharan Africa have focused on communicable diseases, such as Human Immunodeficiency Virus (HIV), Tuberculosis (TB), and Malaria, and on reducing infant mortality [United Nations, 2015], with almost no focus on neurodevelopmental disorders such as ASD [23]. Epidemiological work in LMICs requires true validation of tools, or else it risks inaccurately representing the magnitude of the issue [24].

Although ASDs in LMICs still face a lot of barriers, countries without data about the prevalence of Autism and its impact on the population are making efforts to raise awareness about ASDs through different organizations and institutions. There is clearly a need to put in place research infrastructure, research funding, research capacity, and inclusive education policies to see an improvement in the quality of life of people with Autism Spectrum Disorders and bring their acceptance into society.

References[edit | edit source]

  1. Volkmar, F., Siegel, M., Woodbury-Smith, M., King, B., McCracken, J. and State, M., 2014. Practice parameter for the assessment and treatment of children and adolescents with an autism spectrum disorder. Journal of the American Academy of Child & Adolescent Psychiatry, 53(2), pp.237-257.
  2. 2.0 2.1 Sharma SR, Gonda X, Tarazi FI. Autism spectrum disorder: classification, diagnosis, and therapy. Pharmacology & therapeutics. 2018 Oct 1;190:91-104.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Hodges H, Fealko C, Soares N. Autism spectrum disorder: definition, epidemiology, causes, and clinical evaluation. Translational pediatrics. 2020 Feb; 9(Suppl 1): S55.
  4. Steinbrenner JR, Hume K, Odom SL, Morin KL, Nowell SW, Tomaszewski B, Szendrey S, McIntyre NS, Yücesoy-Özkan S, Savage MN. Evidence-Based Practices for Children, Youth, and Young Adults with Autism. FPG Child Development Institute. 2020.
  5. 5.0 5.1 Hahler EM, Elsabbagh M. Autism: A global perspective. Current Developmental Disorders Reports. 2015 Mar;2(1):58-64.
  6. 6.0 6.1 World Health Organization. Autism spectrum disorders & other developmental disorders: From raising awareness to building capacity. Geneva: WHO Document Production Services. 2013 Sep.
  7. 7.0 7.1 7.2 7.3 Fernell E, Eriksson MA, Gillberg C. Early diagnosis of autism and impact on prognosis: a narrative review. Clinical epidemiology. 2013;5:33.
  8. 8.0 8.1 Lord C, Elsabbagh M, Baird G, Veenstra-Vanderweele J. Autism spectrum disorder. The lancet. 2018 Aug 11;392(10146):508-20.
  9. 9.0 9.1 9.2 Alpert JS. Autism: A Spectrum Disorder. The American Journal of Medicine. 2021 Jun 1;134(6):701-2.
  10. 10.0 10.1 10.2 Parmeggiani A, Corinaldesi A, Posar A. Early features of autism spectrum disorder: a cross-sectional study. Italian journal of pediatrics. 2019 Dec;45(1):1-8.
  11. Hyman SL, Levy SE, Myers SM, Kuo D, Apkon S, Brei T, Davidson LF, Davis BE, Ellerbeck KA, Noritz GH, Leppert MO. Executive summary: identification, evaluation, and management of children with autism spectrum disorder. Pediatrics. 2020 Jan 1;145(1).
  12. What is Autism Spectrum Disorder? Available from: (Accessed, 17/032022).
  13. Mohammadzaheri, F., Koegel, L.K., Rezaee, M. and Rafiee, S.M., 2014. A randomized clinical trial comparison between pivotal response treatment (PRT) and structured applied behavior analysis (ABA) intervention for children with autism. Journal of autism and developmental disorders, 44(11), pp.2769-2777.
  14. Reis SM, Gelbar NW, Madaus JW. Understanding the Academic Success of Academically Talented College Students with Autism Spectrum Disorders. Journal of Autism and Developmental Disorders. 2021 Oct 21:1-4.
  15. Masi A, DeMayo MM, Glozier N, Guastella AJ. An overview of autism spectrum disorder, heterogeneity, and treatment options. Neuroscience bulletin. 2017 Apr;33(2):183-93.
  16. Treatment and Intervention Services for Autism Spectrum Disorder. Available from: ( Accessed, 17/03/2022).
  17. DeFilippis M, Wagner KD. Treatment of autism spectrum disorder in children and adolescents. Psychopharmacology bulletin. 2016 Aug 15;46(2):18.
  18. Medical Centric. Autism Spectrum Disorder, Causes, Signs and Symptoms, Diagnosis and Treatment. Available from: [Accessed, 17/03/2022]
  19. Teachings in Education. Autism Spectrum Disorder: ASD. Available from: r29iOjnbbgA [Accessed, 18/03/2022]
  20. World Health Organization. Meeting report: autism spectrum disorders and other developmental disorders: from raising awareness to building capacity: World Health Organization, Geneva, Switzerland 16-18 September 2013.
  21. 21.0 21.1 van’t Hof M, Tisseur C, van Berckelear-Onnes I, van Nieuwenhuyzen A, Daniels AM, Deen M, Hoek HW, Ester WA. Age at autism spectrum disorder diagnosis: A systematic review and meta-analysis from 2012 to 2019. Autism. 2021 May;25(4):862-73.  
  22. 22.0 22.1 Bakare MO, Munir KM. Autism spectrum disorders (ASD) in Africa: a perspective. African journal of psychiatry. 2011 Jul 1;14(3):208-10.
  23. Franz L, Chambers N, von Isenburg M, de Vries PJ. Autism spectrum disorder in sub‐saharan Africa: A comprehensive scoping review. Autism Research. 2017 May;10(5):723-49.
  24. Daley TC, Singhal N, Krishnamurthy V. Ethical considerations in conducting research on autism spectrum disorders in low and middle-income countries. Journal of autism and developmental disorders. 2013 Sep;43(9):2002-14.