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What is Autism Spectrum Disorder?


Definition from DSM-5


According to DSM-5, Autism Spectrum Disorder (ASD) is a lifelong neurodevelopmental disability that characterized by challenges in social communication and restricted, repetitive behaviours that presented in early childhood which cause significant impairment in daily functioning. It is a spectrum disorder that each individual with ASD has distinct set of strengths and weaknesses. Their abilities can vary from highly skilled to severely challenged. Some may require substantial support in daily lives, while others may need less support or live independently.

Early signs of ASD can be noticed by parent or caretakers during the first year and symptoms become more salient at the age of 2 or 3. In some cases, impairment may be mild or not apparent until the child starts school and shows deficit when comparing to their peers.


Examples of social communication and social interaction characteristics related to ASD: 

  • Deficit in having normal back-and-forth conversation

  • Limited sharing of interests, emotions or affect

  • Failed to start social interactions

  • Lack of eye contact and body language

  • Difficulties in understanding nonverbal gestures

  • Difficulties in making friends


Examples of restricted interests and repetitive behaviours related to ASD: 

  • Stereotyped or repetitive motor movements, use of objects, or speech such as lining up toys, hand flipping and echolalia

  • Extreme difficulty tolerating changes in routine

  • Highly restricted, fixated interests that are abnormal in intensity or focus

  • Sensory hyper-or hyposensitivity such as apparent indifference to pain or temperature, and aversion to loud noises




The causes of ASD remain unknown, studies suggested that ASD may influenced by a combination of genetic and environmental factors. In addition, ASD is suggested to be related to genetic factors as research showed that identical twins have a higher rate of having ASD than the fraternal twins. Moreover, recent research found a relationship between ASD and neurological differences in brain.



According to the survey conducted by the Center for Diseases Prevention and Control in the US during 2018, 1 in 44 children has been identified with Autism Spectrum Disorder (ASD) among children aged 8 years, and ASD affects more boys than girls and the gender ratio is 4.2 to 1. In Hong Kong, the prevalence rate of children with ASD aged below 15 is estimated at around 1.4% according to the General Household Survey conducted during 2019 and 2020 by the Census and Statistics Department.


While there is no treatment to “cure” ASD, current interventions focus on symptoms reduction that interfere with everyday functioning and quality of life.


Interventions can be categorized into the following domains: 


  • Behavioral e.g., Applied Behavior Analysis (ABA)

  • Developmental e.g., Speech therapy, Occupational Therapy

  • Social-Relational e.g., social skills training

  • Pharmacological e.g., Medication

  • Psychological e.g., Cognitive-Behavioral Therapy (CBT)


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