Autism spectrum disorder (ASD) refers to a range of conditions characterized by challenges with social skills, repetitive behaviors, speech and nonverbal communication. Autism affects an estimated 1 in 44 children in the United States today. With growing awareness and earlier screening, more people are being diagnosed with autism than ever before.
But autism manifests differently in each person it affects. It’s what is known as a “spectrum disorder”—a group of conditions with similar features. This means autistic people can have a wide range of skills and challenges. Some autistic people may have average to high intelligence and attend college, while others may have more significant learning challenges. No two people with autism are exactly alike.
Signs of autism in children
The most obvious signs of autism usually appear between 2 and 3 years of age. According to the CDC’s developmental milestones, some early signs that a toddler may be autistic include:
- Not responding to their name by 12 months
- Not pointing at objects to show interest (pointing at an airplane flying over) by 14 months
- Not playing “pretend” games (pretending to “feed” a doll) by 18 months
- Avoiding eye contact and wanting to be alone
- Having trouble understanding other people’s feelings or talking about their own feelings
- Delayed speech and language skills
- Repeating words or phrases over and over (echolalia)
- Giving unrelated answers to questions
- Getting upset by minor changes in routines
- Flapping their hands, rocking their body, or spinning in circles
- Having unusual reactions to the way things sound, smell, taste, look, or feel
In some cases, children show hints of future autism from 6 to 12 months of age such as reduced eye contact, lack of facial expressions, or lack of babbling. However, not all babies showing these signs go on to have ASD. Around the first birthday is when more distinct behaviors may emerge.
Signs of autism in older children
In older children who were not diagnosed as toddlers, signs of autism may include:
- Impaired ability to make friends with peers
- Delayed or lack of spoken language
- Excessive focus on certain topics
- Repetitive motions like rocking or spinning
- Lack of pretend or imaginative play
- Over- or under-sensitivity to sounds, textures, tastes
- Inflexibility about routines or schedules
- Difficulty with organizational skills
Older children with autism may have difficulty regulating their emotions and behavior. They may react intensely to noises, lights, clothing textures, and more. Self-injury such as head banging is also possible when overwhelmed or frustrated.
Signs of autism in adults
Some key signs an adult may be autistic include:
- Difficulty making friends and preferring to be alone
- Blunt, literal, or unusual conversational style
- Avoiding eye contact
- Difficulty understanding facial expressions, body language
- Reluctance to be touched
- Disliking any changes to routine
- Narrow, intense interests
- Repetitive behaviors or movements
- Unusual sensory reactions
- Need for strict order and routines
Many adults struggle with executive function and organizational skills, like planning, multitasking, remembering details from a conversation. Meltdowns can occur due to feeling overwhelmed when too much is happening at once.
When to see a doctor
Parents often first suspect autism when their child does not meet typical developmental milestones, such as pointing, pretend play, or speaking words. Some children with autism reach these milestones at the expected ages, but show other unusual behaviors.
The American Academy of Pediatrics recommends that all children be screened for autism at their 18-month and 24-month well child checkups. Tell your child’s doctor if any autism symptoms concern you in between scheduled appointments as well.
Adults wondering if they may have undiagnosed autism should consider an assessment if they’ve had social struggles that interfere with relationships or jobs. A diagnosis can help people better understand themselves and get support.
Diagnosing autism
There is no medical test, like a blood test or brain scan, that can diagnose autism. Trained specialists diagnose autism by observing behaviors and developmental patterns.
After a pediatrician screens for autism risk during well child visits, they may refer a child for autism testing if concerns arise. A developmental pediatrician, psychologist, speech therapist or other providers specializing in autism may further evaluate the child.
Testing is usually multi-disciplinary and aims to assess social skills, language and communication, intelligence, motor skills, behavior and more. Some examples of autism assessment tools include:
- Autism Diagnostic Observation Schedule (ADOS)
- Autism Diagnostic Interview
- Childhood Autism Rating Scale (CARS)
- Gilliam Autism Rating Scale
Parent interviews are also a key part of an autism evaluation for children. The doctor will ask about the child’s developmental history and behaviors observed at home.
Adults seeking an autism diagnosis may go through a similar multi-step assessment process with psychologists or neuropsychologists. Adults are often interviewed about their childhood as well as current behaviors.
Autism spectrum disorder criteria
To receive an autism diagnosis, a person must meet criteria outlined in the American Psychiatric Association’s Diagnostic and Statistical Manual, Fifth Edition (DSM-5). The criteria include:
- Ongoing deficits in social communication and interaction, such as difficulty having conversations and connecting with others.
- Restricted, repetitive patterns of behaviors, interests, or activities, such as repetitive speech or movements, strict adherence to routines, fixated interests.
- Symptoms present since early childhood (though may not fully manifest until social demands exceed limited capacities).
- Symptoms together limit and impair everyday functioning.
Autism occurs along a spectrum. People must exhibit enough of the criteria symptoms to be diagnosed, but the exact symptoms and their severity varies widely. Autism may be mild or more severe.
Levels of autism support needs
When diagnosing autism, the doctor may categorize the person as Level 1, 2 or 3 to indicate the degree of support needed. The DSM-5 uses these qualifiers:
- Level 1: Requiring support
- Level 2: Requiring substantial support
- Level 3: Requiring very substantial support
People with Level 1 autism typically have mild challenges with communication and social skills. They may manage well with support at school, work or home. Those on Level 2 struggle more significantly in social settings and need more support in daily activities. People with Level 3 autism usually have very limited speech and communication abilities, along with more restrictive repetitive behaviors.
Autism spectrum disorders
Autism spectrum disorder encompasses separate sub-types of autism that were previously diagnosed individually. These include:
- Asperger’s syndrome – Considered “high-functioning autism.” Average or high intelligence and milder symptoms.
- Pervasive developmental disorder-not otherwise specified (PDD-NOS) – Broader range of severity but reduced autism symptoms.
- Childhood disintegrative disorder – Significant loss of language and motor skills after two years of normal development.
Rett syndrome and childhood disintegrative disorder are very rare. PDD-NOS and Asperger’s used to be separate diagnoses, but now fit under the broader autism spectrum disorder diagnosis.
Is autism genetic?
Research indicates autism likely has a genetic component, based on patterns observed in twin studies and families. However, there is no single identified “autism gene.” Instead, researchers believe a combination of genetic mutations passed down from parents combine with environmental risk factors to influence development of autism in a child.
Parents who have one autistic child face an increased chance of having a second child with autism. Studies of identical twins show if one twin has autism, the other twin will also have it about 75-95% of the time. For fraternal twins, the concordance for ASD is lower at around 25-30%.
In about 10% of autism cases, autistic individuals have what’s known as copy number variation – sections of DNA that are deleted or duplicated, disrupting gene function. Methylation of genes has also been noted in some autistic people – an epigenetic change affecting gene expression.
Brain differences
Autistic individuals tend to have different brain structure and connectivity than non-autistic people. Some key neurological differences include:
- Fewer Purkinje cells in the cerebellum
- Enlarged brain size and volume (most notably in early childhood)
- Reduced functional connectivity between key brain regions
- Patches of abnormal laminar architecture and cortical organization
- Higher levels of growth-related proteins in early childhood
MRIs of children with autism commonly show increased white and grey matter volume until around age 2-4. Then their brain volumes tend to plateau while peers’ keep growing. This early overgrowth is followed by slowed growth in later childhood.
While these differences are seen across groups, brain characteristics vary significantly from person to person on the autism spectrum. There are few clear biomarkers that could diagnose someone based on brain scan patterns alone.
Neurotypes / The intense world theory
The intense world theory posits that autistic individuals may subjectively perceive the world more intensely due to greater connectivity in local neural networks. Autism researcher Dr. Henry Markram developed this theory to explain why autistic children seem overwhelmed by noisy environments they cannot tune out.
In this model, the world may appear overstimulating, chaotic, and even threatening due to hyper-awareness. Retreating and restricting stimuli provides relief. Repetitive motions may calm the body. While speculative, this offers perspective on behaviors.
Possible risk factors
Researchers continue investigating what factors might increase risk for autism, though many questions remain unanswered. Some potential autism risk factors include:
- Advanced parental age: Children born to older parents are at higher risk, likely due to increased occurrence of genetic mutations.
- Prenatal/perinatal complications: Metabolic conditions in mom during pregnancy, premature birth, low birth weight, fetal distress, etc.
- SSRI antidepressants: Some studies link prenatal SSRI exposure to increased ASD risk, but findings are mixed.
- Air pollution: Environmental exposure to air pollution including fine particulate matter and ozone may increase autism risk to a small degree.
Other speculative risk factors like vitamin D deficiency, induced or augmented labor, ultrasounds, and more require further study to determine if any true correlation exists.
Is there a cure for autism?
There is currently no medical “cure” for autism spectrum disorder. However, early intervention can greatly improve outcomes. Prescription medications and therapy can also help manage associated symptoms that often accompany ASD.
Applied behavior analysis (ABA therapy) is the most effective researched autism intervention. This involves using positive reinforcement to teach communication, social, motor and cognitive skills – essentially rewiring the brain’s developmental trajectory.
Treatment strategies depend on the person’s needs and may include speech therapy, physical therapy, social skills training, sensory integration therapy and more. Medications like antipsychotics can help manage affiliated behavioral challenges when necessary.
Outlook and long-term development
Autism is a lifelong condition that manifests differently across a spectrum. Early developmental intervention offers the best chance for positive long-term outcomes.
Some children can catch up to peers enough to attend mainstream classrooms and blend in socially. Others have more support needs or intellectual disability requiring specialized education and care. It’s impossible to predict long-term progress at the time of diagnosis.
Around 50% of autistic children gain some phrase speech by age 5. About 25% of children on the spectrum remain nonverbal. Over time, symptoms may lessen, intensify, vary by the year, or remain constant—it depends on the individual.
Autistic adults still face challenges with communication, social skills, and rigidity despite early intervention. But with accommodation, self-understanding, and treatment, adults can live independent, productive and fulfilling lives.
Takeaway
Here are some key takeaways:
- Autism manifests through restricted/repetitive behaviors and social/communication challenges.
- Symptoms appear by age 2-3 but may go unrecognized until later ages.
- Diagnosis is based on developmental patterns, not medical tests.
- ASD has genetic factors but how genes interact with environment is still unknown.
- Intervention at the earliest age possible benefits development.
- Support needs vary from minimal to extensive across the autism spectrum.
- There is no “cure” but early intensive therapy teaches new skills.
- Autistic individuals deserve acceptance, accommodations, and respect.
If concerned your child may have autism, trust instincts and seek an evaluation. If diagnosed with ASD, work closely with therapists to build critical skills during early childhood brain plasticity. Be patient with the process – small gains accumulate over time. Finally, connect with other autism parents for solidarity during challenges.
