ADHD vs Autism: Key Differences & Similarities

In this overview, we will define ADHD and autism, break down diagnostic criteria, highlight key contrasts and parallels, and outline effective strategies for diagnosis and treatment. Gaining a better understanding of both disorders is crucial for parents, teachers, clinicians, and anyone else looking to support individuals living with ADHD, autism, or both.

What Is ADHD?

ADHD is a neurodevelopmental condition characterized by ongoing struggles in multiple domains including problems with attention, excessive activity levels, and problems controlling impulses.

According to the diagnostic criteria outlined in the DSM-5, individuals with ADHD exhibit persistent difficulties with inattention such as trouble following conversations or completing tasks, as well as hyperactive behavior such as excessive fidgeting, difficulty remaining seated and impulsive behavior such as frequently interrupting others.

To receive a diagnosis, six or more specific symptoms must be present before age 12 and lead to impairment in daily functioning. Stimulant medications and behavioral therapies are commonly used to help manage ADHD symptoms.

What Is Autism?

Autism refers to a group of complex neurodevelopmental conditions characterized by challenges with social communication and restrictive or repetitive behaviors. Individuals on the autism spectrum have difficulties relating socially, reading subtle nonverbal cues, expressing themselves verbally and nonverbally, and adjusting to change.

The term "spectrum" indicates that autism encompasses a wide range of symptoms and abilities—some individuals may be nonverbal while others have only mild challenges with language. Early behavioral therapies, speech-language services, social skills training, and classroom accommodations are often used to address needs. Treatment is tailored to the individual, as autism varies greatly from person to person. Medications are primarily used to target aggressive or self injurious behavior and do not directly treat the core symptoms of Autism.

Key Differences Between ADHD and Autism

While ADHD and autism spectrum disorder may share some common behavioral manifestations and executive dysfunction, there are notable distinctions between the two conditions. In addition to the differences in diagnostic criteria, there are differences in the typical age of onset, and the nature of social interaction and communication challenges are different in the two groups of individuals. Gaining clarity on these core differences is crucial for accurate diagnosis and treatment.

Diagnostic Criteria

In contrast to ADHD, autism spectrum disorder is diagnosed based on the presence and severity of social communication deficits and restrictive, repetitive behaviors. The DSM-5 diagnostic criteria for autism center on social-emotional reciprocity, verbal and nonverbal communication, developing relationships, as well as ritualized interests and repetitive movements.

Age of Onset

The typical age of onset and developmental window also differs between ADHD and autism. ADHD symptoms generally emerge between the ages of 3-6 years old, as executive functioning skills and self-regulation capacities are developing and being observed in a preschool to early elementary school setting. However, autism spectrum disorder usually becomes apparent a bit earlier between 12-18 months of age, as communication and language skills typically begin to emerge in neurotypical children.

Early subtle symptoms of autism are sometimes detectable in infancy through reduced eye contact, diminished facial recognition abilities, and lack of back-and-forth gesturing. Catching the early red flags can facilitate prompt diagnosis and treatment.

Social Interaction and Communication

One of the starkest contrasts between ADHD and autism involves social interaction and communication challenges. People with autism tend to have far more pronounced difficulties with social skills, reading social cues, reciprocal conversation, making eye contact, and using nonverbal communication appropriately.In adulthood, ADHD can make some aspects of social interaction more challenging due to impulsivity and distractibility, but the core social deficits experienced by those with autism spectrum disorder are typically far more pervasive and impairing. Understanding this distinction is key in determining the accurate diagnosis and right interventions.

Shared Traits and Overlapping Symptoms

While ADHD and autism spectrum disorder have distinct diagnostic criteria and typical age of onset, there are some shared traits between the two conditions in terms of executive functioning problems, sensory sensitivities, and co-morbid diagnoses. In addition, in both diagnoses, it is not uncommon for children to exhibit disruptive behavior. However what underlies this disruptive behavior is different in both groups.

Executive Functioning Deficits

Both individuals with ADHD and autism often struggle with executive functioning skills including organization, time management, planning, prioritizing tasks, and remembering details. These cognitive difficulties can make it hard to stay focused, control impulses, regulate behavior, and complete tasks from start to finish.

Sensory Sensitivities

Many people with ADHD and autism spectrum disorder experience sensory processing issues in the form of hypersensitivities or hyposensitivities to certain sounds, textures, tastes, smells, colors, or other sensory stimuli. For example, loud noises may be painful or distracting while certain clothing fabrics cause extreme discomfort. Although sensory sensitivities are more commonly seen in individuals with Autism Spectrum Disorder, these may also be reported by individuals with ADHD.

These sensory sensitivities can lead to feelings of agitation, anxiety, confusion, or withdrawal in overstimulating environments. Finding ways to manage and accommodate individual sensory needs is an important treatment goal for individuals with both ADHD and autism.

Co-Occurring Diagnoses

Research indicates that many individuals meet diagnostic criteria for both ADHD and autism spectrum disorder. Comorbidity rates are substantial, with 50 to 70% of autistic individuals also exhibiting ADHD traits.

As awareness and assessment practices continue improving, clinicians are identifying more instances of co-occurring neurodevelopmental disorders such as ADHD and autism that require an integrated treatment approach.

Diagnosis and Treatment Strategies

Obtaining an accurate and comprehensive diagnosis is the crucial first step to accessing evidence-based treatments and services for ADHD and autism spectrum disorder. Early screening and diagnosis are highly beneficial for both conditions. Identifying ADHD and autism early on and beginning appropriate interventions during key developmental windows can improve long-term outcomes.

Comprehensive Diagnostic Process

Thorough evaluation by a trained clinician is vital. Assessment often involves psychiatric examination, psychological testing, completion of rating scales, speech-language screening, occupational therapy evaluation, and gathering insights from parents, teachers, and other caregivers. Screening for co-occurring conditions is also important.

ADHD Treatment

Treatment for ADHD typically consists of behavioral therapy to start as well as the possible addition of adrenergic medications such as Catapres and Tenex, non stimulant ADHD specific medications such as Strattera or Qelbree or stimulant medications such as Adderall or Ritalin to improve focus, memory, and impulse control by normalizing neurotransmitter levels in the brain. Behavioral therapies are recommended to teach organizational skills, emotional regulation techniques, social skills training, and coping mechanisms.

Autism Treatment

Treatment for autism spectrum disorder emphasizes early implementation of behavioral therapies such as Applied Behavior Analysis to build communication, social, academic, and life skills. Speech therapy, occupational therapy, and making classroom accommodations are also often beneficial.

There are 2 medications (Risperdal and Abilify) that are FDA approved to treat Autism related irritability that manifests as aggressive behavior, self injurious behavior and/or tantrums. Other medications are sometimes used off-label to address specific symptoms like anxiety or compulsiveness, there are currently no FDA-approved pharmacological treatments for the core symptoms of autism. An integrated treatment approach with various therapies and accommodations tailored to the individual is ideal.

The Bottom Line

ADHD and autism are complex conditions that may share some overlapping traits but differ in the specific diagnostic criteria, age of onset, and degree of social communication deficits present. Gaining an understanding of the key differences—as well as similarities—will allow parents, educators, and professionals to make informed choices about diagnosis and treatment options.

With appropriate support, people with ADHD, autism, or both conditions can thrive. While these disorders create challenges, they also confer unique strengths. Focusing on identifying and cultivating individual gifts allows people with neurodevelopmental differences to live full and meaningful lives.

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