The United Nations General Assembly unanimously declared 2 April as World Autism Awareness Day (A/RES/62/139) to highlight the need to help improve the quality of life of those with autism so they can lead full and meaningful lives as an integral part of society.
Autism, or autism spectrum disorder (ASD), refers to a broad range of conditions characterized by challenges with social skills, repetitive behaviours, speech and nonverbal communication. According to the Centers for Disease Control, autism affects an estimated 1 in 54 children in the United States today.
We know that there is not one autism but many subtypes, most influenced by a combination of genetic and environmental factors. Because autism is a spectrum disorder, each person with autism has a distinct set of strengths and challenges. The ways in which people with autism learn, think and problem-solve can range from highly skilled to severely challenged. Some people with ASD may require significant support in their daily lives, while others may need less support and, in some cases, live entirely independently.
Several factors may influence the development of autism, and it is often accompanied by sensory sensitivities and medical issues such as gastrointestinal (GI) disorders, seizures or sleep disorders, as well as mental health challenges such as anxiety, depression and attention issues.
Indicators of autism usually appear by age 2 or 3. Some associated development delays can appear even earlier, and often, it can be diagnosed as early as 18 months. Research shows that early intervention leads to positive outcomes later in life for people with autism.
Signs of autism in adults and teens
Do you suspect that your feelings and behaviors involve autism? Many people who have milder forms of autism go undiagnosed until adulthood. Find out more in this guide: “Is it Autism and If So, What Next?”
What Are the Symptoms of Autism?
Autism’s core symptoms are:
- social communication challenges and
- restricted, repetitive behaviors.
Symptoms of autism may:
- begin in early childhood (though they may go unrecognized)
- persist and
- interfere with daily living.
Specialized healthcare providers diagnose autism using a checklist of criteria in the two categories above. They also assess autism symptom severity. Autism’s severity scale reflects how much support a person needs for daily function.
Many people with autism have sensory issues. These typically involve over- or under-sensitivities to sounds, lights, touch, tastes, smells, pain and other stimuli.
Autism is also associated with high rates of certain physical and mental health conditions.
Social communication challenges
Children and adults with autism have difficulty with verbal and non-verbal communication. For example, they may not understand or appropriately use:
- Spoken language (around a third of people with autism are nonverbal)
- Eye contact
- Facial expressions
- Tone of voice
- Expressions not meant to be taken literally
Additional social challenges can include difficulty with:
- Recognizing emotions and intentions in others
- Recognizing one’s own emotions
- Expressing emotions
- Seeking emotional comfort from others
- Feeling overwhelmed in social situations
- Taking turns in conversation
- Gauging personal space (appropriate distance between people)
Restricted and repetitive behaviours
Restricted and repetitive behaviours vary greatly across the autism spectrum. They can include:
- Repetitive body movements (e.g. rocking, flapping, spinning, running back and forth)
- Repetitive motions with objects (e.g. spinning wheels, shaking sticks, flipping levers)
- Staring at lights or spinning objects
- Ritualistic behaviours (e.g. lining up objects, repeatedly touching objects in a set order)
- Narrow or extreme interests in specific topics
- Need for unvarying routine/resistance to change (e.g. same daily schedule, meal menu, clothes, route to school)
What Causes Autism?
The information below is not meant to diagnose or treat. It should not take the place of consultation with a qualified healthcare professional.
A common question after an autism diagnosis is what is the cause of autism.
We know that there’s no one cause of autism. Research suggests that autism develops from a combination of genetic and nongenetic, or environmental, influences.
These influences appear to increase the risk that a child will develop autism. However, it’s important to keep in mind that increased risk is not the same as cause. For example, some gene changes associated with autism can also be found in people who don’t have the disorder. Similarly, not everyone exposed to an environmental risk factor for autism will develop the disorder. In fact, most will not.
Autism’s genetic risk factors
Research tells us that autism tends to run in families. Changes in certain genes increase the risk that a child will develop autism. If a parent carries one or more of these gene changes, they may get passed to a child (even if the parent does not have autism). Other times, these genetic changes arise spontaneously in an early embryo or the sperm and/or egg that combine to create the embryo. Again, the majority of these gene changes do not cause autism by themselves. They simply increase risk for the disorder
Autism’s environmental risk factors
Research also shows that certain environmental influences may further increase – or reduce – autism risk in people who are genetically predisposed to the disorder. Importantly, the increase or decrease in risk appears to be small for any one of these risk factors:
- Advanced parent age (either parent)
- Pregnancy and birth complications (e.g. extreme prematurity [before 26 weeks], low birth weight, multiple pregnancies [twin, triplet, etc.])
- Pregnancies spaced less than one year apart
- Prenatal vitamins containing folic acid, before and at conception and through pregnancy
No effect on risk
- Vaccines. Each family has a unique experience with an autism diagnosis, and for some it corresponds with the timing of their child’s vaccinations. At the same time, scientists have conducted extensive research over the last two decades to determine whether there is any link between childhood vaccinations and autism. The results of this research is clear: Vaccines do not cause autism. The American Academy of Pediatrics has compiled a comprehensive list of this research.
Differences in brain biology
How do these genetic and nongenetic influences give rise to autism? Most appear to affect crucial aspects of early brain development. Some appear to affect how brain nerve cells, or neurons, communicate with each other. Others appear to affect how entire regions of the brain communicate with each other. Research continues to explore these differences with an eye to developing treatments and supports that can improve quality of life.