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Autism (ASD): Levels, Symptoms, Causes, Treatment, & More

Autism Spectrum Disorder is a condition that affects individuals differently, with symptoms ranging from mild to severe. Approximately 1 in 54 children in the United States are diagnosed with autism spectrum disorder, highlighting its prevalence and significance as a developmental concern (1).

What is Autism Spectrum Disorder?

Autism Spectrum Disorder (ASD) is a condition that affects the neurological and developmental aspects of individuals, influencing their communication skills, interactions with others, learning abilities, and behavior patterns (2).

ASD is termed a “developmental disorder” because it typically becomes evident within the initial two years of life (3). It’s referred to as a “spectrum” disorder due to the wide array of symptoms and their varying degrees of severity among affected individuals (4).

Autism Spectrum Disorder may occur in people of any race, ethnicity, sex, or socioeconomic background. While it may persist throughout one’s life, interventions and support services might ease symptoms and enhance daily functioning (5).

Levels of Autism Spectrum Disorder

Autism Spectrum Disorder is categorized into three levels based on the severity of symptoms and the degree of support needed. Think of these levels as a spectrum, akin to the colors of a rainbow, illustrating the varying challenges individuals with ASD may encounter. Here’s an overview of the three levels:

  • Level 1: Requiring Support. At this level, individuals may exhibit noticeable communication difficulties, struggle with social interactions, and face challenges in adapting to changes in routine. They may find it challenging to plan and organize tasks systematically, which may impact various aspects of daily life, necessitating some level of support (6).
  • Level 2: Requiring Substantial Support. Individuals at this level often experience more pronounced impairments in verbal and nonverbal communication. They may have minimal social interaction and exhibit restricted, repetitive patterns of behavior. Coping with changes may be particularly challenging, and individuals may display an intense focus on specific interests or activities, requiring substantial support to navigate daily life (7).
  • Level 3: Requiring Very Substantial Support. This level is characterized by severe impairments in both verbal and nonverbal communication, along with minimal to no social interaction. Individuals may have limited speech and may become agitated or aggressive in response to changes in their environment or routine. They often engage in highly repetitive behaviors that significantly impact their ability to function independently, necessitating intensive support (8).

Symptoms of Autism Spectrum Disorder

Below are examples of common behaviors observed in individuals diagnosed with Autism Spectrum Disorder (ASD) (9). It’s important to note that not all individuals with ASD will exhibit all of these behaviors, but many will display several.

Social Communication and Interaction Behaviors

  • Limited or inconsistent eye contact
  • Delayed or minimal response to their name or verbal cues for attention
  • Challenges with conversational turn-taking
  • Seeming disengaged during conversations, not looking at or listening to others
  • Rarely sharing interests, emotions, or enjoyment in activities with others
  • Expressing mismatched facial expressions, movements, or gestures
  • Unusual tone of voice, sounding either sing-song or monotone
  • Engaging in monologues on favorite topics without noticing a lack of interest from others
  • Struggles adapting behavior to different social situations
  • Limited engagement in imaginative play or difficulty making friends
  • Difficulty understanding others’ perspectives or predicting their actions

Restrictive and Repetitive Behaviors

  • Intense and enduring interests in specific subjects like numbers, details, or facts
  • Hyperfocus on particular objects or parts of objects
  • Repetitive behaviors like repeating words or phrases (echolalia)
  • Sensory sensitivity, such being either more or less sensitive to stimuli like light, sound, or temperature
  • Distress or difficulty with changes in routine or transitions
  • Individuals with ASD may also experience sleep disturbances and irritability


  • Detailed learning and long-term information retention
  • Proficiency in areas like mathematics, science, music, or art
  • Strong visual and auditory learning abilities

While these symptoms provide insights into potential challenges individuals may face, it’s important to remember that each person’s experience with ASD is unique. Seeking support from qualified healthcare professionals and fostering an inclusive environment might significantly enhance the quality of life for individuals with ASD.

Causes of Autism Spectrum Disorder

Understanding the precise cause of Autism Spectrum Disorder (ASD) remains a complex puzzle for researchers. While genetic and environmental factors are believed to contribute, it’s important to note that ASD is multifaceted, with various factors potentially interacting to influence its development. Here’s what current research suggests:

  • Genetic Factors: ASD has been linked to several genes, indicating a genetic component to its development. In some cases, children with ASD may have associated genetic disorders like Rett syndrome or fragile X syndrome. Additionally, mutations in certain genes might increase the likelihood of ASD, affecting brain development and communication between brain cells. It’s worth noting that these genetic mutations might either be inherited or occur spontaneously (10).
  • Environmental Influences: Researchers are actively investigating environmental factors that may contribute to ASD. These factors could include viral infections, certain medications, complications during pregnancy, or exposure to air pollutants. While the exact mechanisms are still being studied, it’s believed that these environmental influences might play a role in triggering ASD in susceptible individuals (11).

By acknowledging the complexity of ASD and the ongoing research into its causes, we can better appreciate the nuances of this condition and work towards effective interventions and support for individuals and families affected by it.

Autism Spectrum Disorder Risk Factors

The prevalence of autism spectrum disorder (ASD) diagnosis in children is on the rise. It remains uncertain whether this increase is primarily due to improved detection and reporting, an actual surge in cases, or a combination of both. ASD can affect children of all ethnicities and backgrounds, but certain factors may elevate a child’s risk. These factors include:

  • Family History: Families with one child diagnosed with ASD have a heightened risk of having another child with the disorder. Additionally, it’s not uncommon for parents or relatives of a child with ASD to exhibit mild difficulties in social interaction or communication skills, or to display behaviors associated with the disorder (12).
  • Sex: Boys (assigned males at birth) appear to be approximately four times more likely to develop ASD compared to girls (assigned females at birth), although the reasons for this discrepancy are not fully understood (13).
  • Parental Age: Some studies suggest a potential link between advanced parental age and ASD risk, but further research is needed to confirm this association conclusively (14).
  • Premature Birth: Extremely premature infants, born before 26 weeks of gestation, may face a heightened risk of ASD (15).
  • Coexisting Disorders: Children with certain medical conditions are at an increased risk of ASD or ASD-like symptoms. Examples include fragile X syndrome, a genetic disorder characterized by intellectual impairment; tuberous sclerosis, a condition marked by the development of noncancerous tumors in the brain; and Rett syndrome, a genetic disorder predominantly affecting girls, resulting in slowed head growth, intellectual disability, and loss of hand function (16).

It’s essential to recognize that each child’s experience with ASD is unique, and outcomes may vary significantly. More research is necessary to fully understand the complexities of ASD and its associated risk factors.

Diagnosis of Autism Spectrum Disorder

Healthcare providers diagnose ASD by observing a person’s behavior and developmental patterns. Typically, ASD may be reliably diagnosed by the age of 2, stressing the importance of seeking evaluation promptly to initiate necessary treatments and services at an early stage.

Diagnosis in Young Children

Diagnosing ASD in young children typically involves a two-step process (18).

Step 1: General Developmental Screening During Routine Checkups

Routine well-child checkups, conducted by pediatricians or early childhood healthcare providers, play a crucial role. The American Academy of Pediatrics advises developmental screening for all children during their 9-, 18-, and 24- or 30-month checkups, with specific autism screenings at 18 and 24 months. Additional screenings may be recommended for children at higher risk of ASD or developmental issues (19).

Taking into account caregivers’ observations and concerns is integral during these screenings. Healthcare providers may inquire about the child’s behaviors, integrating this information with ASD screening tools and clinical observations. For more information on ASD screening tools, refer to the Centers for Disease Control and Prevention (CDC) website. If a child exhibits developmental disparities during this screening, further evaluation may be warranted.

Step 2: Additional Diagnostic Assessment

Early and accurate detection of ASD is crucial for understanding an individual’s unique strengths and difficulties. Timely diagnosis aids caregivers in identifying suitable services, educational programs, and behavioral therapies for the child (20).

A multidisciplinary team with expertise in ASD diagnosis typically conducts the evaluation. This team may comprise child neurologists, developmental-behavioral pediatricians, speech-language pathologists, child psychologists, psychiatrists, educational specialists, and occupational therapists.

The diagnostic evaluation typically requires:

  • Medical and neurological examinations
  • Assessment of speech and language skills
  • Behavioral observations
  • Evaluation of cognitive abilities
  • Evaluation of age-appropriate daily living skills, such as self-care tasks
  • Inquiry into the family history of the child
  • Discussions with caregivers about the child’s development and behavior
  • Given the complexity of ASD, which might co-occur with other conditions, comprehensive evaluations may involve blood tests and hearing assessments

Following this evaluation, a formal diagnosis and recommendations for treatment may be provided.

Diagnosing Older Children and Adolescents

Symptoms of ASD in older children and teenagers are often noticed first by caregivers and educators within the school environment. The school’s special education team might conduct an initial assessment and then suggest further evaluation by the child’s primary healthcare provider or a specialist in ASD (21).

Caregivers may discuss the child’s social struggles, which may involve difficulties in understanding subtle social cues like tone of voice, facial expressions, or body language. Older individuals with ASD might also encounter challenges comprehending figures of speech, humor, or sarcasm, as well as forming friendships with peers.(22)

Diagnosing Adults

Identifying ASD in adults poses particular challenges due to potential overlap with symptoms of other mental health conditions such as anxiety disorders or attention-deficit/hyperactivity disorder (ADHD) (23).

Adults who recognize signs of ASD are advised to consult a healthcare professional and request a referral for an evaluation. While diagnosing ASD in adults is still evolving, referrals may be made to neuropsychologists, psychologists, or psychiatrists experienced in ASD. These experts typically inquire about:

  • Social and communication difficulties
  • Repetitive behaviors
  • Specific interests
  • Sensory sensitivities

The evaluation process might involve gathering information from caregivers and family members regarding the individual’s developmental history to ensure an accurate diagnosis.

Receiving a proper ASD diagnosis may provide insight into past challenges, highlight personal strengths, and facilitate access to appropriate support. Ongoing research aims to identify effective services and interventions for enhancing the well-being and integration of autistic individuals in childhood, adolescence, and adulthood.

Treatment Options for Autism Spectrum Disorder

Commencing treatment for Autism Spectrum Disorder (ASD) promptly post-diagnosis is crucial. Early intervention is key as it might mitigate challenges individuals face and aid in acquiring new skills and enhancing existing ones (24).

ASD presents a spectrum of challenges, implying that there isn’t a one-size-fits-all solution. Collaborating closely with healthcare providers is essential in determining the most suitable blend of treatments and support services (24).


In certain cases, healthcare providers may recommend medication to address specific symptoms (25). Medication might potentially alleviate issues such as:

  • Aggression
  • Irritability
  • Hyperactivity
  • Repetitive behavior
  • Anxiety and depression
  • Attention Concerns

Behavioral, Psychological, and Educational Interventions

Individuals with ASD might be directed toward specialists offering behavioral, psychological, educational, or skill-building interventions. These interventions typically involve structured and intensive programs, often including involvement from caregivers, siblings, and other family members (26). These interventions aim to help individuals with ASD:

  • Diminish behaviors hindering daily functioning
  • Develop social, communication, and language skills
  • Acquire life skills conducive to independent living
  • Enhance existing strengths or acquire new ones

Additional Resources

Numerous services, programs, and resources are accessible to support individuals with ASD. Here are some suggestions for locating these additional resources:

  • Reach out to healthcare providers, local health departments, schools, or autism advocacy groups to explore specialized programs or local resources.
  • Engage with an autism support group. Sharing insights and experiences may be invaluable in discovering treatment options and ASD-related initiatives.
  • Maintain records of conversations and meetings with healthcare providers and educators.

Remember, what works for one person with ASD may not be as effective for another. Embracing the variability and individuality within the spectrum is fundamental to finding the most beneficial treatments.

By staying informed, actively engaging with healthcare providers, and tapping into available resources, individuals with ASD and their families might make empowered decisions tailored to their specific needs and goals.

Autism Spectrum Disorder and Co-existing Conditions

Individuals diagnosed with autism may experience various coexisting conditions, which could include:

  • Attention deficit/hyperactivity disorder (ADHD) in children: Characterized by symptoms such as restlessness, easy distractibility, difficulty maintaining focus on uninteresting tasks, heightened sensitivity to stimuli like color and light, and challenges with behavior regulation (27).
  • Behavioral challenges: These may encompass fixation on specific objects or toys, tendencies toward obsessive-compulsive behaviors, possessiveness over objects, and reactive aggression or irritability when disruptions occur in their areas of intense interest (28).
  • Anxiety: Individuals with autism often exhibit signs of anxiety, which may manifest as situational distress, irritability, anger, and physical symptoms like body aches, headaches, or disrupted sleep patterns (29).
  • Depression: Difficulty in communication and social interaction might predispose autistic individuals to experiences of stress, fluctuating weight, restlessness, and symptoms consistent with depression (30).
  • Sleep disorders: A prevalent issue affecting a significant portion (approximately 50–80%) of individuals with autism. These disturbances in sleep patterns may also influence daytime behaviors (31).
  • Seizures: There is an increased risk of seizures among children with autism. Management often necessitates ongoing medical intervention to effectively control seizures (32).
  • Intellectual disability: Around one-third of individuals diagnosed with autism may also experience global developmental delay or intellectual disabilities, impacting their learning abilities and necessitating substantial support in daily activities (33).

It’s crucial to approach each individual with autism holistically, recognizing the unique combination of challenges they may face. By understanding and addressing co-existing conditions alongside ASD, we can better support individuals in reaching their full potential and improving their quality of life.

Prevention of Autism Spectrum Disorder

While it’s not possible to definitively prevent autism spectrum disorder, there are steps individuals may take to potentially reduce the risk . Early detection and intervention play pivotal roles in managing symptoms and fostering improved behavior, skills, and language development. Lowering the risk of having a child with autism spectrum disorder involves various measures, including:

  • Maintaining a Healthy Lifestyle: Regular visits to healthcare providers, consumption of a balanced diet, and regular exercise are essential. Adequate prenatal care, as well as adhering to recommended vitamin and supplement regimens, are crucial during pregnancy (34).
  • Avoiding Alcohol Consumption: It’s imperative to stay away from consuming alcohol during pregnancy, as no amount is considered safe for fetal development (35).
  • Medication Management: Consult with healthcare providers about the safety of medications during pregnancy, and follow their guidance regarding usage (36)

By adhering to these guidelines, individuals might potentially mitigate the risk factors associated with autism spectrum disorder. However, it’s essential to recognize the complexity of this condition and the variability in individual experiences. It’s recommended to consult with healthcare professionals for personalized guidance and support.


It’s essential to recognize that individuals with autism have unique strengths and abilities that should be celebrated (37). While autism may present challenges, it’s crucial to approach it with understanding and acceptance. By fostering a supportive and inclusive environment, individuals with autism can thrive and lead fulfilling lives.