Early diagnosis of autism spectrum disorder is key, as it allows for timely intervention. Early interventions, such as behavior, speech, and occupational therapies, can address delayed communication, social skills, and behavior. With a proper diagnosis, families can access appropriate resources and support, reducing their stress and improving their quality of life.

What Is Autism Spectrum Disorder?
Autism spectrum disorder (ASD) is a lifelong developmental condition that affects communication, behavior, and social interactions [1]. People with ASD may exhibit unusual behaviors, such as focusing on small details, having trouble switching tasks, or unusual reactions to sensations.
The word “spectrum” means there is a wide range of how autism can affect people. Every person with autism has their own strengths and challenges. Some may have severe intellectual disability, others average intelligence, or others above-average intelligence. Many people with autism also have special skills, such as remembering things well, paying close attention to detail, or noticing patterns.
In 2010, researchers estimated that 1 in 132 people worldwide had autism. By 2016, about 1 in 54 children in the United States were diagnosed with ASD. According to the CDC, in 2020, about 1 in 36 children at age 8 years old were identified with ASD. [2] Autism is more commonly diagnosed in boys than girls, with a ratio of about four boys for every girl.
People with autism may struggle with starting or responding to social communication cues, such as facial expressions, tone and volume, and eye contact. [1]. They may require assistance in understanding some implicit rules of social interactions, such as the appropriate distance one should maintain with someone, taking turns in a conversation, or even knowing when the other is not paying attention or is agitated.
When they have an ASD diagnosis, people may also exhibit restrictive and/or repetitive patterns of behavior. They may get upset if their schedule or environment changes. Autistic people may also exhibit hand-flapping, rocking, or echolalia, in which certain phrases or words may be presented over and over again. Some have reported diminished or heightened responses to sensory inputs, including lights, sounds, textures, or even smells. While a few people who have ASD might develop a strong liking or fascination with certain topics, others may focus on certain subjects and attain the most expert status on quite a few of them.
Early Signs of Autism
Two of the most important things you can do as a caregiver or parent are to become aware of the developmental milestones that your child should attain and to learn the early signs of autism. There are several common signs prevalent in children who have ASD. Not all children with autism have these behaviors, and others without autism might display only some of these behaviors. This is why it’s essential to get a professional evaluation.
Here are some signs you’ll see:
By 6 months
- Limited or no eye contact
- Few or no big smiles and little or no use of facial expressions
- Little or no babbling
By 9 months
- May not show interest in shared experiences
- May not engage with caregivers
By 12 months
- Limited or absent verbal communication
- Little or no response to their name
- Limited or no back-and-forth gestures, such as waving, pointing, or reaching
By 2 years
- May exhibit delayed language development or may not speak at all
- Some may repeat words or phrases they’ve heard or speak in a monotone voice
- Lack of engagement in simple, social games and may prefer to play alone
- May have delays in motor skills or may exhibit clumsy or awkward movements
Autism Screening Process
The earlier a child is diagnosed with autism, the sooner they can begin to benefit from available treatment and intervention. The American Academy of Pediatrics (AAP) recommends a developmental and behavioral assessment for all children at ages 9, 18, and 30 months by a pediatrician or a family medicine physician who is competent in pediatric care [3]. They further recommend ASD-specific assessment at 18 and 24 months.
Healthcare professionals may use standardized developmental screening tools to check for developmental delays or signs of autism. Examples include:
- Ages and Stages Questionnaire (ASQ): A general screening tool for assessing developmental milestones
- Modified Checklist for Autism in Toddlers (M-CHAT): A parent-completed questionnaire for children ages 16–30 months
Often, researchers ask parents and caregivers to complete questionnaires or surveys about the child’s behavioral and developmental history. These include questions about social behavior, language development, and routine behavior. If the initial assessment indicates the possibility of autism or developmental disorders, the pediatrician or primary care provider will usually refer the child to a specialist for further evaluation.
Comprehensive Diagnosis of ASD
Making an appropriate diagnosis of ASD requires a comprehensive process that includes many components to assess a person’s behavior, development, communication, and social interactions. The aim of the assessment is to determine if a person meets the criteria for ASD. The analysis also helps rule out other conditions that may have similar features. An ASD assessment should include the following components.
Developmental and Medical History
As part of the assessment, the clinician gathers extensive details regarding the child’s life in the prenatal, natal, and early years, including whether there were any speech, social, or motor delays and any related concerns. A family history of ASD or any other developmental issue may also be important. Similarly, they obtain the child’s overall health, record of illness and immunization, and anything that would interfere with development (such as hearing problems or seizures).
Direct Observation of the Child
The clinician observes the child in the testing environment, during classroom activities, and at home. The practitioner gathers first-hand information about the child’s symptoms to help make the diagnosis. Some structured and semi-structured observations have been developed to help practitioners. The most dependable means of diagnosing ASD is the ADOS-2. It is a play-based evaluation in which the clinician attentively watches the child’s interactions, communications, and play behaviors.
Cognitive and Language Assessments
Cognitive testing and language assessments are used to capture a person’s cognitive abilities and language levels. The assessment looks at language, motor skills, flexible functioning milestones, and any developmental delays or developmental abnormalities in these areas. Doctors use tools such as the Wechsler Intelligence Scale for Children (WISC-V) or the Bayley Scale of Infant and Child Development (Bayley-4).
Social-Emotional and Behavioural Assessments
In addition to these specific checks for autism, behavioral testing may be used to detect other disorders that may overlap with autism symptoms, such as anxiety, depression, or attention deficit disorder/attention deficit-hyperactivity disorder (ADD/ADHD). To address the behavioral, emotional, and social issues that may be presented, the evaluation might use tools such as the Behaviour Assessment System for Children, Second Edition (BASC-3) or Conners Rating Scales.
Diagnostic Criteria for Autism Spectrum Disorders
The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) is the
handbook that healthcare professionals use in the diagnosis of ASD. It describes characteristic features of the disorder and sets out the criteria for making the diagnosis.
A person must meet the following criteria in order to be said to be on the spectrum. The first requirement is that the person must have persistent deficits in social communication and social interaction across multiple contexts, as manifested by the following characteristics, either currently or historically:
- Observations of restricted, repetitive patterns of behavior, interests, or activities
- Symptoms must be present in the early developmental period
- Symptoms cause clinically significant impairment in social, occupational, or other important areas of current functioning
- These disturbances cannot be better explained by intellectual disability (intellectual developmental disorder) or global developmental delay
In addition to the listed criteria, the DSM-5 also includes a severity scale for ASD based on the level of support required:
- Level 1: Requiring support
- Level 2: Requiring substantial support
- Level 3: Requiring very substantial support
This severity rating helps to describe the individual’s level of impairment and the degree of support needed for daily functioning.
Challenges in Diagnosing Autism
A diagnosis of ASD can be a complex and multifaceted process, affected by a variety of challenges and potential barriers. Potential challenges and obstacles include:
Age at Diagnosis
ASD is more manageable when detected early. However, the symptoms of ASD are often not fully apparent until later in childhood, usually around 2–3 years of age. In some cases, children are misdiagnosed with other conditions, such as ADHD, anxiety, and developmental delays, before an accurate diagnosis of ASD is made.
Cultural and Societal Factors
Cultural norms determine how individuals behave and interact socially. Due to differences in social norms, communication styles, and behavioral expectations, people may view ASD differently across cultures. For example, in some cultures, children may be expected to be more introverted or submissive, which can be mistaken for social withdrawal or a lack of communication skills—characteristics that may overlap with ASD.
In many countries, there is a stigma attached to ASD and other developmental disorders. As a result, parents are reluctant to consult a doctor for a diagnosis because of fear for their child.
Gender Differences
Research has shown that ASD manifests differently in females compared to males [4]. Although males tend to display overt, stereotypical behaviors associated with ASD (such as having fewer repetitive activities and interests), females may be more adept at disguising those behaviors or revealing subtle social challenges. Consequently, girls with ASD may be either undiagnosed or misdiagnosed later than boys.
Because girls with ASD may not have rigid symptoms, they are often misdiagnosed with other conditions, such as anxiety, ADHD, or even personality disorders. Undiagnosed ASD in women can lead to unmet needs.
Variability in Symptoms
Since ASD is a spectrum disorder, it manifests in symptoms of varying nature and severity. Individuals who have autism may exhibit symptoms related to communication, association, and behavior. However, these can vary from person to person, making it difficult to adopt a single diagnostic approach.
Diagnostic Tools and Criteria
ASD can’t be diagnosed with specific objective measures, like blood tests or imaging; instead, ASD is noted by subjective means, like behavioral observations and developmental history. Although diagnostic tools, such as the DSM-5 and the ADOS-2, are widely used, they’re dependent on the expertise of the clinicians and might not capture the various types of ASD. Additionally, tools are limited in how to differentiate ASD from other developmental and psychological conditions that share similar symptoms.
Some of the conditions that present similarly to ASD are these:
- Anxiety Disorders: Children with both ASD and anxiety disorders may be socially withdrawn, be cut off from social contact, or have a problem adapting. Anxiety disorders are primarily caused by fear, worry, and stress reactions. In contrast, deficits in social communication and the presence of restricted, repetitive patterns of behavior in ASD are not present from only the influence of fear; instead, they result from the influences of several factors.
- Attention-Deficit/Hyperactivity Disorder (ADHD): Attention, impulsiveness, and culturally accepted social norms may be a problem in either ADHD or ASD. The major difference between the two diagnoses is that in ADHD, the deficits are more centered on paying attention and regulating emotions instead of speech concerns and social deficits. Also, people with attention-deficit hyperactivity disorder (ADHD) have core symptoms of hyperactivity and lack of focus, as opposed to having restrictive modes of behavior and interests.
- Intellectual Disability (ID): Children suffering from ID, including autistic children, may present with language difficulties, language impairment, lack of socialization, and the inability to develop age-appropriate skills. However, it should be pointed out that an individual with autism does not have to be intellectually disabled, as average and even above-average intelligence quotients are reported among those who have autism.
What Happens After An Autism Diagnosis?
Establishing an early diagnosis of ASD is essential for enrollment in ASD-specific interventions [5]. After the assessment, there are specific measures that can be taken to ensure that the child gets the care, attention, education, and therapy needed.
- Understanding the Diagnosis: After an ASD diagnosis has been made, parents or caregivers may attend a meeting with the healthcare provider about the implications of the diagnosis for their child, as well as where on the spectrum of ASD the testing indicates.
- Early Intervention: Early intervention is essential for children with autism, as it can lead to positive long-term outcomes in terms of social interaction and language skills.
- Individualized Education Plan (IEP) or 504 Plan: When a child reaches school age, early intervention programs generally transition to educational settings. A child may be eligible for services under an Individualized Education Plan (IEP) or 504 plan if they attend a public school. Both programs are designed to ensure that the child receives appropriate support within their educational environment.
- Family Support and Counseling: Parent training and support groups can help parents learn how to best support their children’s development.
- Hodges, H., Fealko, C., & Soares, N. (2020, February). Autism spectrum disorder: definition, epidemiology, causes, and clinical evaluation. Translational pediatrics, 9(Suppl 1), S55–S65. https://pmc.ncbi.nlm.nih.gov/articles/PMC7082249/
- Centers for Disease Control and Prevention. (2023, March 24). Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 8 Years — Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2020. https://www.cdc.gov/mmwr/volumes/72/ss/ss7202a1.htm
- Centers for Disease Control and Prevention. (2024, November 26). Screening for Autism Spectrum Disorder. https://www.cdc.gov/autism/diagnosis/index.html
- Tsirgiotis J. M., Young R. L., Weber N. (2023, August 22). A Comparison of the Presentations of Males and Females with Autism Spectrum Disorder and those Narrowly Below the Diagnostic Threshold. https://journals.sagepub.com/doi/10.1177/13623613231190682
- Suma K., Adamson L. B., Bakeman R., Robins D. L., Abrams D. N. (2017, August 1). After Early Autism Diagnosis: Changes in Intervention and Parent-Child Interaction. https://pmc.ncbi.nlm.nih.gov/articles/PMC5108300/
Our Medical Affairs Team is a dedicated group of medical professionals with diverse and extensive clinical experience who actively contribute to the development of our content, products, and services. They meticulously evaluate and review all medical content before publication to ensure it is medically accurate and aligned with current discussions and research developments in mental health. For more information, visit our Editorial Policy.
MentalHealth.com is a health technology company guiding people towards self-understanding and connection. The platform provides reliable resources, accessible services, and nurturing communities. Its purpose is to educate, support, and empower people in their pursuit of well-being.

Michael Quinn is a writer with five years of experience unpacking everything from technology and politics to medicine and telecommunications.
Jennie Stanford is a dual-board certified physician in both family medicine and obesity medicine, holding an MD, FAAFP, and DipABOM. She has experience in both clinical practice and peer-quality reviews.
Our Medical Affairs Team is a dedicated group of medical professionals with diverse and extensive clinical experience who actively contribute to the development of our content, products, and services. They meticulously evaluate and review all medical content before publication to ensure it is medically accurate and aligned with current discussions and research developments in mental health. For more information, visit our Editorial Policy.
MentalHealth.com is a health technology company guiding people towards self-understanding and connection. The platform provides reliable resources, accessible services, and nurturing communities. Its purpose is to educate, support, and empower people in their pursuit of well-being.