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About Autism

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Awareness of autism spectrum disorder (ASD) has increased dramatically over the past decade. This has led to intense calls for a better understanding of autism worldwide, not only scientifically and medically, but also in terms of how cultural, ethnic, geographic, and socioeconomic factors influence diagnosis and treatment.

Some efforts have already been undertaken to understand from a global perspective how differing perceptions and definitions of autism affect families worldwide. Challenging behaviors and other symptoms of autism are often seen in widely different ways depending on cultural traditions which may profoundly affect how families cope with challenges posed by an autistic family member.

In some parts of the world, early detection, identification, diagnosis, and intervention are difficult simply because of the limited availability of autism treatment resources, lack of linguistically-and culturally-appropriate assessment tools, untrained school personnel, the absence of specialized schools, and economic limitations. Other barriers reflect systematic gaps in healthcare offerings, care coordination, and lack of exposure to autism during medical training. Additionally, in many cultures, parents experience social stigma for having a child with ASD. The stigmatization associated with autism remains a significant obstacle to families seeking assessment, formal evaluation, and diagnosis.

Global prevalence estimates for ASD are difficult to ascertain because of limited international epidemiological studies. It is suspected that there exist many autistic individuals worldwide who are living undiagnosed and without any treatment or intervention. Most estimates, including that of the World Health Organization (2021) put ASD prevalence at approximately 1 percent of the population worldwide, most likely reflecting common genetic causes across all of humanity. A global map of autism prevalence ( created by the team at Spectrum, presents a survey of studies on autism prevalence around the world.

The United Nations General Assembly (2007) unanimously declared April 2 as World Autism Awareness Day to highlight the need to help improve the quality of life of those on the spectrum. The day brings autism organizations together to advocate for greater awareness, research, and understanding, all with the aim of contributing to improved quality of life for those on the spectrum. Global initiatives are taking shape to improve screening practices and diagnostic methods, deliver culturally-appropriate services, train service providers, and provide education and advocacy resources and tools for leaders of these organizations.

Although definitions of autism and perspectives on autism may vary from country to country, it is generally accepted that autism is a lifelong neurological condition that manifests during early childhood, irrespective of gender, race or socioeconomic status. Autism is characterized by unique social interactions, inclination toward routines, challenges in verbal communications, and sensory sensitivities. The symptoms of people with ASD fall on a continuum, with some individuals showing mild symptoms and others having much more severe symptoms.

In 2018, the World Health Organization (WHO) released its International Classification of Diseases 11th Revision (ICD-11). The ICD-11 catalogues different conditions to provide clinicians worldwide with common language and a standard set of criteria for diagnosis that are broad enough to translate across cultures and can be applied anywhere in the world. The ICD-11 lists difficulties in social interaction and social communication, restricted interests and repetitive behaviors, unusual sensory sensitivities, and the loss of previously acquired competences as characteristics to be taken into account when making a diagnosis of autism. An insistence on strict rules and on imposing those rules on others may be common among autistic people. The ICD-11 also provides detailed guidelines for distinguishing between autism with and without intellectual disability.


Autism Europe. (2018, June). World Health Organization updates classification of autism in the ICD-11.

Chung, K.M., Woohyun, J., Ben-Itzchah, E., Zachor, D., Furniss, F., Heyes, K., Matson, J., Kozlowski, A., & Barker, A. (2012). Cross cultural differences in challenging behaviors of children with autism spectrum disorders: An international examination between Israel, South Korea, the United Kingdom, and the United States of America. Research in Autism Spectrum Disorders, 6(2), 881-889.

Elsabbagh, M., Divan, G., Koh, Y.,  Kim, Y.S., Kauchali, S., Marcín, C., Montiel-Nava, C.,  Patel, V., Paula, C.S., Wang, C., Yasamy, M.T., Fombonne, E. (2012). Global prevalence of autism and other pervasive developmental disorders. Autism Res. 5(3), 160–179.

Elsabbagh, M. & Hahler, E. (2015). Autism: A Global Perspective. Current Developmental Disorders Reports, 2, 58–64.

Gary, J., and  Rubin, N.S. (2015, June) Global awareness of autism spectrum disorder: Impact and interventions. Psychology International.

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Spectrum (Simons Foundation). (2021). Autism by the Numbers: Explaining its Apparent Rise. Spectrum’s Guide to Prevalence Estimates. Puritan Press, Inc.

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United Nations. (2012). World Autism Awareness Day. United Nations.

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World Health Organization. (2021, June 1). Autism Spectrum Disorder. World Health Organization.

World Health Organization. (2018, June). WHO releases new International Classification of Diseases (ICD 11).

World Health Organization (2021). International Statistical Classification of Diseases and Related Health Problems (ICD).

Autism in the US

Autism spectrum disorder (ASD) in the US is commonly defined as a complex developmental disability, which significantly affects a person’s behavior and his/her ability to communicate and interact socially. The signs of autism often appear early and, in most cases, last a person’s lifetime. About 1 in 36 children in the United States (US) has been identified with an autism spectrum disorder (ASD), and it is approximately four times as prevalent among boys as among girls, according to estimates from the US CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network.

Autistic individuals have a wide range of challenges, interests, and needs. In general, ASD refers to a range of conditions typically characterized by some degree of difficulty in the areas of social skills, repetitive behaviors, and speech and communication. Individuals on the spectrum may experience some level of motor skill differences, language and communication challenges, intellectual impairment, executive function difficulties, emotional challenges, and sensory sensitivities. Some individuals on the spectrum require a great deal of assistance with daily living tasks while others can care for themselves independently.

The US Centers for Disease Control and Prevention (CDC) (2018) provides the following examples of possible signs and symptoms of autism that children or adults with ASD may exhibit:

  • May not point at objects to show interest
  • May not look at objects when another person points at them
  • May have trouble relating to others
  • May avoid eye contact
  • May have trouble understanding other people’s feelings or talking about their own feelings
  • May prefer not to be held or cuddled
  • May appear to be unaware when people talk to them, but respond to other sounds
  • May be very interested in people, but not know how to talk, play, or relate to them
  • May repeat or echo words or phrases said to them
  • May have trouble expressing their needs using typical words or motions
  • May repeat actions over and over again
  • May have trouble adapting when a routine changes
  • May have unusual reactions to the way things smell, taste, look, feel, or sound

Autism is considered a “spectrum” disorder because individuals vary significantly in the type and severity of symptoms. Two individuals with the same diagnosis can act quite differently from one another and have varying capabilities, behaviors, and strengths.

In 2023, researchers from the US Centers for Disease Control and Prevention published a study indicating that 26.7% of 8-year-old children with autism in the United States have what’s known as “profound autism” (children were classified as having “profound autism” if they were nonverbal, minimally verbal, or had an intelligence quotient of less than 50). The finding is based on surveillance data collected through the CDC’s Autism and Developmental Disabilities Monitoring Network, which conducts research on the prevalence of autism among 8-year-olds in several communities across the United States. Compared with children with non-profound autism, children with profound autism were more likely to be female, from racial and ethnic minority groups, of low socioeconomic status, born preterm or with low birth weight, have self-injurious behaviors, have seizure disorders, and have lower adaptive scores. At this stage, much remains unknown about the profound autism population, and further research focused on this subpopulation is critical to ensuring that this group receives appropriate services and supports throughout the life course.

Some individuals on the spectrum exhibit surprising and unique abilities, intense passions, and highly-specific intellectual and artistic interests. Many have individualistic ways of learning and engaging with the world, and may need understanding and guidance to discover and master an approach that works best for them.

Given the challenges of caring for autistic individuals, many physicians and clinicians find themselves underprepared for the complexity of diagnoses, the diversity of presentations, and the coordination of care across specialties throughout the lifespan. A great need in medical education is better training in how to best care for adults on the spectrum, particularly those with comorbid health conditions. Comorbid medical and health issues that affect individuals on the spectrum includes seizures, anxiety, depression, gastrointestinal disorders, immune dysfunction, metabolic abnormalities, mitochondrial dysfunction, sleep disturbances, food sensitivities and intolerances, and attention deficit hyperactivity disorder.

There is no approved medical test to diagnose autism. Currently, diagnosis in the US is based on observation of development and behavioral symptoms outlined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition Text Revision (DSM-5 TR). Because symptoms vary considerably from individual to individual, diagnosis can be quite challenging, and since it is a developmental disability, autism affects individuals differently at different stages of their lifespan. The full diagnostic criteria for autism spectrum disorder can be found in the DSM-5 TR.


American Psychiatric Association. (2022). Neurodevelopmental disorders. In Diagnostic and statistical manual of mental disorders (5th ed., text rev.).

Baio J, Wiggins L, Christensen DL, et al. Prevalence of Autism Spectrum Disorder Among Children Aged 8 Years — Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2014. MMWR Surveill Summ 2018;67(No. SS-6):1–23.

Division of Birth Defects, National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention. (2018, May). Basics About ASD.

Division of Birth Defects, National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention (2015, February). Autism Spectrum Disorder: Screening and Diagnosis.

Hughes MM, Shaw KA, DiRienzo M, et al. The Prevalence and Characteristics of Children With Profound Autism, 15 Sites, United States, 2000-2016. Public Health Reports. 2023;0(0).

Hyman, S.L. (2013). New DSM-5 includes changes to autism criteria. AAP News, June 2013.

Lord, C., et al. (2022). The Lancet Commission on the future of care and clinical research in autism. The Lancet, 399(10321), 271-334.

Maenner MJ, Shaw KA, Baio J, et al. Prevalence of Autism Spectrum Disorder Among Children Aged 8 Years — Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2016. MMWR Surveill Summ 2020;69(No. SS-4):1–12.

Maenner MJ, Warren Z, Williams AR, et al. Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 8 Years — Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2020. MMWR Surveill Summ 2023;72(No. SS-2):1–14.

McDougle, C.M. (Ed.). (2016). Primer on Autism Spectrum Disorder. New York, NY: Oxford University Press.

Spectrum (Simons Foundation). (2021). Autism by the Numbers: Explaining its Apparent Rise. Spectrum’s Guide to Prevalence Estimates. Puritan Press, Inc.

Cause, Cure, & Interventions

There is no single cause of autism spectrum disorder. Many theories regarding the etiology of autism have been proposed and explored and a general explanation has not been established. It is generally accepted that the condition of autism is influenced by genetic, immunological, metabolic, and environmental factors. Biomedical research has focused on unstable gene clusters, sporadic (uninherited) gene mutations, viral infections during pregnancy, metabolic imbalances, exposure to chemicals and environmental toxins, prematurity and obstetric complications during delivery.

There are currently no medications that can cure ASD. Some medications can treat associated symptoms of autism and help individuals with autism achieve greater independence on a daily basis. Medications do not affect all autistic individuals in the same way, and in some cases, it is questioned whether the negative side effects of the treatment outweigh benefits.

Research has shown that early diagnosis and early intervention can lead to significantly improved outcomes and can help children with autism learn important skills, including how to communicate using electronic devices and to engage with others in social activities. Early intervention focuses on helping young children learn basic physical, cognitive, communication, social/emotional, and self-help skills. Treatments and interventions for autism include Applied Behavior Analysis (ABA), Treatment and Education of Autistic and Related Communication-handicapped Children (TEACCH), Developmental Individual-Difference Relationship-based Model/Floortime, Relationship Development Intervention, auditory training, intensive educational therapy, sensory integration therapy, music therapy, play therapy, augmentative and alternative communication (AAC) strategies, including supported typing and the Picture Exchange Communication System (PECS), pharmacological treatments, and comprehensive treatment programs. Many individuals benefit from yoga, speech therapy, hippo-therapy, occupational training, physical therapy, art and music lessons.

Autism Across the Lifespan

Although much press is given to the ‘tragedy of childhood autism’ it is life-long condition. Although autism affects individuals throughout the lifespan, only a small part of the growing investment in autism research, education, and best care practices is directed at problems faced by adults. The reality is that the majority of children on the spectrum grow up to become adults who are left with significantly fewer resources and options. Because the nature of supports changes considerably as people with autism age, a greater variety of services and programs geared toward adults are needed to ensure a higher quality of life for people with autism as they age.

As individuals on the spectrum transition out of high school, there are a number of post-school options that must be considered, such as postsecondary education, vocational training, supported employment, independent living, and community participation. As individuals with autism and their parents or caregivers get older, the issue of long-term life planning becomes more acute. Primary caregivers are preoccupied and worried about what will happen once they are gone. Addressing this deep concern can be a complex process as decisions must be made regarding the medical care, living arrangements, daily activities, community participation, employment, religious involvement, guardianship, and long-term financial support. As novel communication devices and strategies become available, individuals on the spectrum will be able to communicate what their hopes are for their later lives and take a more active role in planning how to achieve them.

It is important to challenge the usual assumptions about how adults on the spectrum view and think about the world. The assumption, for example, that autistic persons do not wish to socialize, based on observed behaviors in social settings, has profound effects on the way they are treated (Jaswal and Akhtar, 2018). Uncovering alternative explanations for these behaviors and challenging the assumption that autistic people are not interested in socializing is as important as basic biomedical research in guaranteeing healthy and productive lives for those with autism.


Jaswal, V., & Akhtar, N. (2018). Being vs. Appearing Socially Uninterested: Challenging Assumptions about Social Motivation in Autism. Behavioral and Brain Sciences, 1-84.

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Arlington, VA: American Psychiatric Association, 2013.

Baio J, Wiggins L, Christensen DL, et al. Prevalence of Autism Spectrum Disorder Among Children Aged 8 Years — Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2014. MMWR Surveill Summ 2018;67(No. SS-6):1–23. DOI:

Hyman, S.L. (2013). New DSM-5 includes changes to autism criteria. AAP News, June 2013.

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