Adult ADHD and Autism: Understanding the Nuances and Overlap of the Two

ADHD and autism often co-occur and share overlapping traits, but are still widely misunderstood in adults. Many adults are misdiagnosed or dismissed, especially if they don’t fit the outdated stereotypes of either condition. At NeuroSpark Health, we specialize in adult ADHD and autism assessments that are affirming, inclusive, and grounded in lived experience.

What is Attention-Deficit/Hyperactivity Disorder (ADHD)?

Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental condition often diagnosed in childhood—but many adults remain undiagnosed well into their 30s, 40s, or later. ADHD affects focus, self-regulation, and executive functioning. Recent years have brought increased awareness, and more adults are now seeking ADHD evaluations to better understand their challenges and strengths.

Common Signs of Adult ADHD

• Difficulty starting or finishing tasks
• Daydreaming or mental “wandering”
• Forgetfulness or losing things often
• Fidgeting or restlessness
• Talking excessively or interrupting
• Hyperfocus on specific interests or tasks
• Risk-taking or impulsivity
• Difficulty maintaining relationships
• Executive functioning challenges

Types of ADHD (According to DSM-5-TR)

• Predominantly Inattentive Type – Trouble staying organized, following instructions, or completing tasks.
• Predominantly Hyperactive-Impulsive Type – Restlessness, excessive talking, impulsivity.
• Combined Type – A mix of inattentive and hyperactive-impulsive traits.

→ Read more about our ADHD assessment process 

Gender Bias in ADHD Diagnosis

ADHD is more frequently diagnosed and treated in people assigned male at birth (AMAB) than in people assigned female at birth (AFAB). AFAB individuals are consistently underidentified and underdiagnosed, and age at diagnosis tends to be later. This disparity is likely due to a combination of gender bias, differences in symptom presentation, and outdated stereotypes.

What is Autism?

Autism is another neurotype, marked by sensory, social, and information-processing differences. While often diagnosed in childhood, many autistic adults, especially women, BIPOC individuals, and high-masking professionals, go unrecognized for years.

Common Signs of Autism in Adults

• Stimming
• Sensory sensitivities (light, sound, texture)
• Difficulty with eye contact or nonverbal cues
• Intense interests (aka special interests)
• Insistence on routine or sameness
• Difficulty expressing emotions (alexithymia)
• Exhaustion from socializing or masking

→ More women are getting autism diagnoses—here’s why

Late-Diagnosed or Misdiagnosed Autistic Adults

Adults may go undiagnosed due to masking, outdated diagnostic criteria, or co-occurring conditions. Traits might have been misinterpreted as anxiety, OCD, or personality disorders.

At NeuroSpark Health, we use lived experience as a valid source of diagnostic insight, offering affirming assessments for autistic adults.

What is AuDHD?

AuDHD refers to individuals who are both autistic and ADHD. These dual diagnoses are common, yet frequently overlooked or misunderstood in adult evaluations. 

Shared Traits Between ADHD and Autism

• Executive functioning challenges
• Sensory sensitivities
• Emotional dysregulation
• Difficulty with social nuance
• Hyperfocus or intense interests
• Masking or camouflaging behaviors

These overlapping traits can complicate diagnosis. A comprehensive, neurodiversity-affirming evaluation is essential for clarity.

Why Adult ADHD and Autism Are Often Missed

• Diagnostic criteria were developed for children, not adults
• Gender and racial biases in research and assessment tools
• High-masking individuals may appear “high functioning”
• Symptoms are often internalized, not disruptive
• Clinicians may lack training in affirming, adult-focused evaluations

How to Get an ADHD and Autism Evaluation as an Adult

If you suspect you may be autistic, ADHD, or both (AuDHD), you’re not alone, and you deserve support that understands the full picture.

At NeuroSpark Health, we offer virtual adult autism and ADHD assessments nationwide. Our approach is affirming, personalized, and grounded in real-world experience. We specialize in high-masking, late-identified, and multiply neurodivergent adults.

→ Learn more about our dual ADHD and autism assessments
→ Book a free 15-minute consultation