Awareness around autism spectrum disorder is growing around the world, and scientists are learning more about it every day.

According to a 2022 study published in Autism Research, about 100 in 10,000 (or one in 100) children around the world are diagnosed with autism spectrum disorder.

This is an increase from a 212 global prevalence report, which found that 62 in 10,000 children were autistic. Scientists say that the increase in autism prevalence “reflects the impact of public health efforts to raise global awareness of autism spectrum disorder”.

Autism is neither an illness nor a medical condition with treatments or a “cure” but autism is a spectrum, which means everybody with autism is different and has different needs.

So what is autism spectrum disorder and how common is it? Here’s everything you need to know:

Autism spectrum disorders (ASD) are a diverse group of conditions. They are characterized by some degree of difficulty with social interaction and communication. Other characteristics are atypical patterns of activities and behaviors, such as difficulty with transition from one activity to another, a focus on details and unusual reactions to sensations. According to the Centers for Disease Control and Prevention (CDC), ASD is diagnosed more often in boys than in girls.


It is estimated that worldwide about one in 100 children has autism. 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 autism in many low and middle income countries is unknown.


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

Available epidemiological data conclude that there is no evidence of a causal association between measles, mumps and rubella vaccine, and autism. 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 autism. Evidence reviews of the potential association between the preservative thiomersal and aluminium adjuvants contained in inactivated vaccines and the risk of autism strongly concluded that vaccines do not increase the risk of autism.

The exact cause of ASD is unknown. The most current research demonstrates there’s no single cause.

Some suspected risk factors for ASD include:

  • Having an immediate family member who’s autistic
  • Certain genetic mutations
  • Fragile X syndrome and other genetic disorders
  • Being born to older parents
  • Low birth weight
  • Metabolic imbalances
  • Exposure to heavy metals and environmental toxins
  • A maternal history of viral infections
  • Fetal exposure to the medications valproic acid or thalidomide (Thalomid)

What are the symptoms of autism?

Symptoms of ASD typically become clearly evident during early childhood, between ages 12 and 24 months. However, symptoms may also appear earlier or later.

Early symptoms may include a marked delay in language or social development.

The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) divides symptoms of ASD into two categories:

1) Problems with communication and social interaction

2) Restricted or repetitive patterns of behavior or activities

To be diagnosed with autism, a person must experience symptoms in both of these categories.

  • Problems with communication and social interaction

ASD can involve a range of issues with communication, many of which appear before age 5.

Here’s a general timeline of what this might look like:

  • From birth: trouble maintaining eye contact
  • By 9 months: not responding to their name
  • By 9 months: not displaying facial expressions reflective of their emotions (like surprise or anger)
  • By 12 months: not engaging in basic interactive games, like peek-a-boo or pat-a-cake
  • By 12 months: not using (or only using a few) hand gestures, like hand-waving
  • By 15 months: not sharing their interests with others (by showing someone a favorite toy, for example)
  • By 18 months: not pointing or looking where others point
  • By 24 months: not noticing when others appear sad or hurt
  • By 30 months: not engaging in “pretend play,” like caring for a baby doll or playing with figurines
  • By 60 months of age: not playing turn taking games, like duck duck goose
  • Restricted or repetitive patterns of behavior or activities

In addition to the communication and social issues mentioned above, autism also includes symptoms related to body movements and behaviors.

These can include:

  • Repetitive movements, like rocking, flapping their arms, spinning, or running back and forth
  • Lining objects, like toys, up in strict order and getting upset when that order is disturbed
  • Attachment to strict routines, like those around bedtime or getting to school
  • Repeating words or phrases they hear someone say over and over again
  • Getting upset over minor changes
  • Focusing intently on parts of objects, like the wheel of a toy truck or the hair of a doll
  • Unusual reactions to sensory input, like sounds, smells, and tastes
  • Obsessive interests
  • Exceptional abilities, like musical talent or memory capabilities

Other characteristics

Some autistic people might experience additional symptoms, including:

  • Delayed movement, language, or cognitive skills
  • Seizures
  • Gastrointestinal symptoms, like constipation or diarrhea
  • Excessive worry or stress
  • Unusual levels of fear (either higher or lower than expected)
  • Hyperactive, inattentive, or impulsive behaviors
  • Unexpected emotional reactions
  • Unusual eating habits or preferences
  • Unusual sleep patterns

When to see a doctor

Babies develop at their own pace, and many don't follow exact timelines found in some parenting books. But children with autism spectrum disorder usually show some signs of delayed development before age 2 years.

If you're concerned about your child's development or you suspect that your child may have autism spectrum disorder, discuss your concerns with your doctor. The symptoms associated with the disorder can also be linked with other developmental disorders.

Signs of autism spectrum disorder often appear early in development when there are obvious delays in language skills and social interactions. Your doctor may recommend developmental tests to identify if your child has delays in cognitive, language and social skills, if your child:

  • Doesn't respond with a smile or happy expression by 6 months
  • Doesn't mimic sounds or facial expressions by 9 months
  • Doesn't babble or coo by 12 months
  • Doesn't gesture  such as point or wave by 14 months
  • Doesn't say single words by 16 months
  • Doesn't play "make believe" or pretend by 18 months
  • Doesn't say two word phrases by 24 months
  • Loses language skills or social skills at any age


Problems with social interactions, communication and behavior can lead to:

  • Problems in school and with successful learning
  • Employment problems
  • Inability to live independently
  • Social isolation
  • Stress within the family
  • Victimization and being bullied


There's no way to prevent autism spectrum disorder, but there are treatment options. Early diagnosis and intervention is most helpful and can improve behavior, skills and language development. However, intervention is helpful at any age. Though children usually don't outgrow autism spectrum disorder symptoms, they may learn to function well.


Autism also referred to as autism spectrum disorder constitutes a diverse group of conditions related to development of the brain. About one in 100 children has autism. Characteristics may be detected in early childhood, but autism is often not diagnosed until much later. The abilities and needs of autistic people vary and can evolve over time. While some people with autism can live independently, others have severe disabilities and require life long care and support. Evidence based psychosocial interventions can improve communication and social skills, with a positive impact on the well being and quality of life of both autistic people and their caregivers. Care for people with autism needs to be accompanied by actions at community and societal levels for greater accessibility, inclusivity and support.


(1) Global prevalence of autism: A systematic review update. Zeidan J et al. Autism Research 2022 March.

(2) Wakefield's affair: 12 years of uncertainty whereas no link between autism and MMR vaccine has been proved. Maisonneuve H, Floret D. Presse Med. 2012 Sep; French (

(3) Lancet retracts Wakefield’s MMR paper. Dyer C. BMJ 2010;340:c696. 2 February 2010 (

(4) American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Washington, DC: American Psychiatric Association Publishing.

(5) Dietert, R.R, Dietert, J. C., Dewitt, J. C (2011). Environmental Risk Factors for Autism, Emerg. Heath Threats J., 2011, 4:10:3402/ehtj.v4i0.7111

(6) CDC. (2021, April 29). Autism Spectrum Disorder (ASD). Retrieved August 19, 2021, from:




Abdulhakim Bashir Tijjani is a graduate of Human Anatomy from ABU Zaria and currently a 500 level medical student of Bayero University Kano. A Mental Health Advocate and mental health content creator. Values include honesty, respect, love and trust. Have particular interest in Neuropsychiatry. Hobbies are reading, research and traveling.

He can be reach via:

WhatsApp +2348035692189


Twitter/Instagram/Facebook: @abtddm

Latest Comments:

  • 2022-08-13
    Adebiyi Bisola Deborah says:

    Though was a little bit lengthy,yet was worth reading through. Thanks for the enlightenment.

  • 2022-08-13
    Adebiyi Bisola Deborah says:

    Though was a little bit lengthy,yet was worth reading through. Thanks for the enlightenment.

  • 2022-08-13
    Adebiyi Bisola Deborah says:

    Nice write-up.

  • 2022-08-13
    Adebiyi Bisola Deborah says:

    Nice write-up.

  • 2022-08-13
    Adebiyi Bisola Deborah says:

    Nice write-up.

To write a comment, You must be logged in

Login Here SIGN IN