August 14, 2020

Autism Spectrum Disorders (ASD)

Autism is a lifelong developmental disability that affects how people perceive the world and interact with others. Autistic people see, hear and feel the world differently to other people. If you are autistic, you are autistic for life; autism is not an illness or disease and cannot be 'cured'.

In this article:
Definition
Key facts
Epidemiology
Causes
Signs and Symptoms
Assessment and management
Social and economic impact
WHO Resolution on autism spectrum disorders (WHA67.8)

Definition

Autism spectrum disorder (ASD) refers to a range of conditions characterised by some degree of impaired social behaviour, communication and language, and a narrow range of interests and activities that are both unique to the individual and carried out repetitively.

A diagnosis of ASD now includes several conditions that used to be diagnosed separately, including: autistic disorder, pervasive developmental disorder not otherwise specified (PDD-NOS), and Asperger syndrome. These conditions are now all called autism spectrum disorder.

ASDs begin in childhood and tend to persist into adolescence and adulthood. In most cases the conditions are apparent during the first 5 years of life.

Individuals with ASD often present with other co-occurring conditions, including epilepsy, depression, anxiety and attention deficit hyperactivity disorder (ADHD). The level of intellectual functioning in individuals with ASDs is extremely variable, extending from profound impairment to superior levels.

Key facts

The following is a summary of the key facts to note about ASD:
  • One in 160 children has an autism spectrum disorder (ASD).
  • ASDs begin in childhood and tend to persist into adolescence and adulthood.
  • While some people with ASD can live independently, others have severe disabilities and require life-long care and support.
  • Evidence-based psychosocial interventions, such as behavioural treatment and parent skills training programmes, can reduce difficulties in communication and social behaviour, with a positive impact on well-being and quality of life for persons with ASD and their caregivers.
  • Interventions for people with ASD need to be accompanied by broader actions for making physical, social and attitudinal environments more accessible, inclusive and supportive.
  • Worldwide, people with ASD are often subject to stigma, discrimination and human rights violations. Globally, access to services and support for people with ASD is inadequate.

Epidemiology

It is estimated that worldwide one in 160 children has an ASD. This estimate represents an average figure, and reported prevalence varies substantially across studies. Some well-controlled studies have, however, reported figures that are substantially higher. The prevalence of ASD in many low- and middle-income countries is so far unknown.

Based on epidemiological studies conducted over the past 50 years, the prevalence of ASD appears to be increasing globally. There are many possible explanations for this apparent increase, including improved awareness, expansion of diagnostic criteria, better diagnostic tools and improved reporting.

Causes

Available scientific evidence suggests that there are probably many factors that make a child more likely to have an ASD, including environmental and genetic factors.

Available epidemiological data are conclusive that there is no evidence of a causal association between measles, mumps and rubella vaccine, and ASD. Previous studies suggesting a causal link were found to be filled with methodological flaws.

There is also no evidence to suggest that any other childhood vaccine may increase the risk of ASD. Evidence reviews of the potential association between the preservative thiomersal and aluminium adjuvants contained in inactivated vaccines and the risk of ASD strongly concluded that vaccines do not increase the risk of ASDs.

Signs and Symptoms

ASD begins before the age of 3 and last throughout a person’s life, although symptoms may improve over time. Some children with ASD show hints of future problems within the first few months of life. In others, symptoms may not show up until 24 months or later. Some children with an ASD seem to develop normally until around 18 to 24 months of age and then they stop gaining new skills, or they lose the skills they once had. Studies have shown that one third to half of parents of children with an ASD noticed a problem before their child’s first birthday, and nearly 80%–90% saw problems by 24 months of age.

It is important to note that some people without ASD might also have some of these symptoms. But for people with ASD, the impairments make life very challenging.

Possible “Red Flags”

A person with ASD might:
  • Not respond to their name by 12 months of age
  • Not point at objects to show interest (point at an airplane flying over) by 14 months
  • Not play “pretend” games (pretend to “feed” a doll) by 18 months
  • Avoid eye contact and want to be alone
  • Have trouble understanding other people’s feelings or talking about their own feelings
  • Have delayed speech and language skills
  • Repeat words or phrases over and over (echolalia)
  • Give unrelated answers to questions
  • Get upset by minor changes
  • Have obsessive interests
  • Flap their hands, rock their body, or spin in circles
  • Have unusual reactions to the way things sound, smell, taste, look, or feel

Social Skills

Social issues are one of the most common symptoms in all of the types of ASD. People with an ASD do not have just social “difficulties” like shyness. The social issues they have cause serious problems in everyday life.

Examples of social issues related to ASD:
  • Does not respond to name by 12 months of age
  • Avoids eye-contact
  • Prefers to play alone
  • Does not share interests with others
  • Only interacts to achieve a desired goal
  • Has flat or inappropriate facial expressions
  • Does not understand personal space boundaries
  • Avoids or resists physical contact
  • Is not comforted by others during distress
  • Has trouble understanding other people’s feelings or talking about own feelings
Typical infants are very interested in the world and people around them. By the first birthday, a typical toddler interacts with others by looking people in the eye, copying words and actions, and using simple gestures such as clapping and waving “bye bye”. Typical toddlers also show interests in social games like peek-a-boo and pat-a-cake. But a young child with an ASD might have a very hard time learning to interact with other people.

Some people with an ASD might not be interested in other people at all. Others might want friends, but not understand how to develop friendships. Many children with an ASD have a very hard time learning to take turns and share—much more so than other children. This can make other children not want to play with them.

People with an ASD might have problems with showing or talking about their feelings. They might also have trouble understanding other people’s feelings. Many people with an ASD are very sensitive to being touched and might not want to be held or cuddled. Self-stimulatory behaviors (e.g., flapping arms over and over) are common among people with an ASD. Anxiety and depression also affect some people with an ASD. All of these symptoms can make other social problems even harder to manage.

Communication

Each person with ASD has different communication skills. Some people can speak well. Others can’t speak at all or only very little. About 40% of children with an ASD do not talk at all. About 25%–30% of children with ASD have some words at 12 to 18 months of age and then lose them. Others might speak, but not until later in childhood.

Examples of communication issues related to ASD:
  • Delayed speech and language skills
  • Repeats words or phrases over and over (echolalia)
  • Reverses pronouns (e.g., says “you” instead of “I”)
  • Gives unrelated answers to questions
  • Does not point or respond to pointing
  • Uses few or no gestures (e.g., does not wave goodbye)
  • Talks in a flat, robot-like, or sing-song voice
  • Does not pretend in play (e.g., does not pretend to “feed” a doll)
  • Does not understand jokes, sarcasm, or teasing
People with ASD who do speak might use language in unusual ways. They might not be able to put words into real sentences. Some people with ASD say only one word at a time. Others repeat the same words or phrases over and over. Some children repeat what others say, a condition called echolalia. The repeated words might be said right away or at a later time. For example, if you ask someone with ASD, “Do you want some juice?” he or she might repeat “Do you want some juice?” instead of answering your question. Although many children without an ASD go through a stage where they repeat what they hear, it normally passes by three years of age. Some people with an ASD can speak well but might have a hard time listening to what other people say.

People with ASD might have a hard time using and understanding gestures, body language, or tone of voice. For example, people with ASD might not understand what it means to wave goodbye. Facial expressions, movements, and gestures may not match what they are saying. For instance, people with an ASD might smile while saying something sad.

People with ASD might say “I” when they mean “you,” or vice versa. Their voices might sound flat, robot-like, or high-pitched. People with an ASD might stand too close to the person they are talking to, or might stick with one topic of conversation for too long. They might talk a lot about something they really like, rather than have a back-and-forth conversation with someone. Some children with fairly good language skills speak like little adults, failing to pick up on the “kid-speak” that is common with other children.

Unusual Interests and Behaviors

Many people with ASD have unusual interest or behaviors.

Examples of unusual interests and behaviors related to ASD:
  • Lines up toys or other objects
  • Plays with toys the same way every time
  • Likes parts of objects (e.g., wheels)
  • Is very organized
  • Gets upset by minor changes
  • Has obsessive interests
  • Has to follow certain routines
  • Flaps hands, rocks body, or spins self in circles
Repetitive motions are actions repeated over and over again. They can involve one part of the body or the entire body or even an object or toy. For instance, people with an ASD might spend a lot of time repeatedly flapping their arms or rocking from side to side. They might repeatedly turn a light on and off or spin the wheels of a toy car. These types of activities are known as self-stimulation or “stimming.”

Autism Spectrum Disorders (ASD): Autistic boy obsessively stacking cans
Repetitively stacking or lining up objects is associated with autism spectrum.
This 18 month old boy with autism is obsessively stacking cans.
Credit: Andwhatsnext / CC BY-SA
People with ASD often thrive on routine. A change in the normal pattern of the day—like a stop on the way home from school—can be very upsetting to people with ASD. They might “lose control” and have a “melt down” or tantrum, especially if in a strange place.

Some people with ASD also may develop routines that might seem unusual or unnecessary. For example, a person might try to look in every window he or she walks by a building or might always want to watch a video from beginning to end, including the previews and the credits. Not being allowed to do these types of routines might cause severe frustration and tantrums.

Other Symptoms

Some people with ASD have other symptoms. These might include:
  • Hyperactivity (very active)
  • Impulsivity (acting without thinking)
  • Short attention span
  • Aggression
  • Causing self injury
  • Temper tantrums
  • Unusual eating and sleeping habits
  • Unusual mood or emotional reactions
  • Lack of fear or more fear than expected
  • Unusual reactions to the way things sound, smell, taste, look, or feel
People with ASD might have unusual responses to touch, smell, sounds, sights, and taste, and feel. For example, they might over- or under-react to pain or to a loud noise. They might have abnormal eating habits. For instance, some people with an ASD limit their diet to only a few foods. Others might eat nonfood items like dirt or rocks (this is called pica). They might also have issues like chronic constipation or diarrhea.

People with ASD might have odd sleeping habits. They also might have abnormal moods or emotional reactions. For instance, they might laugh or cry at unusual times or show no emotional response at times you would expect one. In addition, they might not be afraid of dangerous things, and they could be fearful of harmless objects or events.

Development

Children with ASD develop at different rates in different areas. They may have delays in language, social, and learning skills, while their ability to walk and move around are about the same as other children their age. They might be very good at putting puzzles together or solving computer problems, but they might have trouble with social activities like talking or making friends. Children with an ASD might also learn a hard skill before they learn an easy one. For example, a child might be able to read long words but not be able to tell you what sound a “b” makes.

Children develop at their own pace, so it can be difficult to tell exactly when a child will learn a particular skill. But, there are age-specific developmental milestones used to measure a child’s social and emotional progress in the first few years of life. To learn more about developmental milestones, visit “Learn the Signs. Act Early,” a campaign designed by CDC and a coalition of partners to teach parents, health care professionals, and child care providers about early childhood development, including possible “red flags” for autism spectrum disorders.

Assessment and management

Intervention during early childhood is important to promote the optimal development and well-being of people with an ASD. Monitoring of child development as part of routine maternal and child health care is recommended.

It is important that, once identified, children with an ASD and their families are offered relevant information, services, referrals, and practical support according to their individual needs. There is no known cure for ASD. Evidence-based psychosocial interventions, however, such as behavioural treatment and skills training programmes for parents and other caregivers, can reduce difficulties in communication and social behaviour, with a positive impact on the person’s well-being and quality of life.

The health-care needs of people with ASD are complex and require a range of integrated services, including health promotion, care, rehabilitation services, and collaboration with other sectors such as education, employment and social care.

Interventions for people with ASD and other developmental disorders need to be accompanied by broader actions for making their physical, social, and attitudinal environments more accessible, inclusive and supportive.

Social and economic impact

ASDs may significantly limit the capacity of an individual to conduct daily activities and participate in society. ASDs often negatively influence the person’s educational and social attainments as well as employment opportunities.

While some individuals with ASD are able to live independently, others have severe disabilities and require life-long care and support.

ASDs often impose significant emotional and economic burden on people with these disorders and their families. Caring for children with a severe form of the condition may be demanding, especially where access to services and support are inadequate. Therefore the empowerment of caregivers is increasingly being recognized as a critical component of care for children with ASD.

Human rights

People with ASD are often subject to stigma and discrimination, including unjust deprivation of health care, education and opportunities to engage and participate in their communities.

People with ASD have the same health problems that affect the general population. Furthermore, they may have specific health-care needs related to ASD or other co-occurring conditions. They may be more vulnerable to developing chronic noncommunicable conditions because of behavioural risk factors such as physical inactivity and poor dietary preferences, and are at greater risk of violence, injury and abuse.

People with ASD require accessible health services for general health-care needs like the rest of the population, including promotive and preventive services and treatment of acute and chronic illness. Nevertheless, people with ASD have higher rates of unmet health-care needs compared with the general population. They are also more vulnerable during humanitarian emergencies. A common barrier is created by health-care providers’ inadequate knowledge of ASD and misconceptions.

WHO Resolution on autism spectrum disorders (WHA67.8)

In May 2014, the Sixty-seventh World Health Assembly adopted a resolution entitled "Comprehensive and coordinated efforts for the management of autism spectrum disorders (ASD)," which was supported by more than 60 countries.

The resolution urges WHO to collaborate with Member States and partner agencies to strengthen national capacities to address ASD and other developmental disorders.

Please see the World Health Assembly resolution WHA67.8: Comprehensive and coordinated efforts for the management of autism spectrum disorders.

In addition, WHO in consultation with experts, parents’ association and civil society organizations, has developed a parent skills training programme which is currently undergoing field-testing.

Please see the WHO Parent Skills Training Package for caregivers of children with developmental disorders.

Reference(s)
1). World Health Organization: Autism spectrum disorders - WHO Fact Sheets. Available online: https://www.who.int/news-room/fact-sheets/detail/autism-spectrum-disorders
2). Centers for Disease Control: Signs and Symptoms of Autism Spectrum Disorders. Available online: https://www.cdc.gov/ncbddd/autism/signs.html

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