Autism

Neurodevelopmental Disorders & Learning Differences

Low Functioning Autism (ASD Level 3): Symptoms, Support Needs, and Communication Challenges

Authored by: The DrSensory Editorial Team

Reviewed by: 🛡️ DrSensory Clinical Review Board

Last updated: June 2025

All medical content on this page has been reviewed and approved by licensed Doctors on the DrSensory Clinical Review Board. Our reviewers follow strict editorial standards and ensure alignment with current APTA guidelines, evidence-based practice, and orthopedic rehabilitation protocols.

What is Low Functioning Autism and how is it classified today?

Low Functioning Autism is an informal term once used to describe individuals on the autism spectrum who have significant challenges with communication, daily living, and adaptive behavior. Today, this group is more accurately described as having Autism Spectrum Disorder (ASD) Level 3, which means they require very substantial support across multiple areas of life.

This includes:

  • Severe speech or nonverbal communication delays
  • Difficulty with social interaction and transitions
  • Intense repetitive behaviors or sensory sensitivities
  • Limited independence in daily tasks

What are the symptoms of Low Functioning Autism in children and adults?

Individuals labeled as having Low Functioning Autism often display symptoms such as:

  • Minimal or no verbal communication
  • Little awareness of social cues or emotions
  • Strong reliance on routines and resistance to change
  • Self-injurious or aggressive behaviors in some cases
  • Extreme sensory sensitivities, such as to sound or touch
  • Cognitive or intellectual disabilities in many cases

These symptoms typically appear in early childhood and persist into adulthood, requiring lifelong support in many areas.

How is Low Functioning Autism diagnosed and what does “ASD Level 3” mean?

Low Functioning Autism is no longer an official diagnosis. Instead, the DSM-5 classifies individuals based on levels of support needed.
ASD Level 3 is the most intensive category and indicates:

  • Very limited verbal communication or social initiation
  • Extreme difficulty coping with change
  • Constant supervision or assistance with daily activities

Diagnosis is made by a developmental pediatrician, neurologist, or psychologist, using tools like the ADOS-2 and adaptive functioning assessments. Early diagnosis allows families to begin intensive support as soon as possible.

What treatments and support options help with Low Functioning Autism?

While there is no cure for autism, children and adults with ASD Level 3 benefit from structured, individualized support programs, including:

  • Applied Behavior Analysis (ABA) for behavioral improvement
  • Speech and language therapy (including AAC devices for nonverbal individuals)
  • Occupational therapy for sensory and motor skill development
  • Special education programs and life skills training
  • Parent and caregiver support or respite care

These interventions can greatly improve communication, reduce distressing behaviors, and enhance quality of life.

Is Low Functioning Autism the same as Nonverbal Autism?

Not exactly. While many individuals once described as having Low Functioning Autism are also nonverbal, the two terms are not interchangeable. Nonverbal Autism refers specifically to people on the spectrum who have little to no spoken language but may still communicate through gestures, devices, or AAC (Augmentative and Alternative Communication).

Low Functioning Autism, now typically diagnosed as ASD Level 3, includes broader challenges beyond speech—such as difficulties with daily living skills, social behaviors, and adaptive functioning.

How does sensory processing affect people with Low Functioning Autism?

Sensory processing challenges are extremely common in individuals with ASD Level 3. Many people experience hypersensitivity (overreacting to stimuli) or hyposensitivity (underreacting). This can affect how they respond to:

  • Sounds (e.g., covering ears at loud noises)
  • Lights or textures
  • Food textures or smells
  • Movement or balance

Visit our page on Sensory Processing and Autism to learn more about how vestibular, proprioceptive, and other sensory systems impact behavior and learning—and what tools can help.

What is the difference between Autism Levels 1, 2, and 3?

Autism is now diagnosed using a three-level system to describe the amount of support an individual needs:

  • Level 1 Autism: Requires support (formerly known as “high-functioning autism”)
  • Level 2 Autism: Requires substantial support
  • Level 3 Autism: Requires very substantial support (previously called Low Functioning Autism)

This classification helps guide intervention planning based on how a person communicates, behaves, and functions in daily life.

How do you support communication in someone with nonverbal or low verbal autism?

For individuals with Low Functioning Autism who are nonverbal, alternative communication tools can open up meaningful interaction. These may include:

  • Picture Exchange Communication Systems (PECS)
  • Speech-generating devices
  • AAC apps on tablets
  • Sign language or gestures

Visit our Nonverbal Autism page for a deeper look at communication options and how therapists use them in speech-language therapy.

Are sensory-friendly environments important for individuals with ASD Level 3?

Yes. Creating sensory-friendly spaces is crucial for individuals with ASD Level 3. These environments help reduce overstimulation and support emotional regulation.

Ideal features include:

  • Soft lighting and minimal background noise
  • Weighted blankets or compression vests
  • Fidget tools or chewable items
  • Calm-down corners

Explore more tools and strategies on our Sensory Processing and Autism page.

Why is the term “Low Functioning Autism” being replaced in clinical use?

The term Low Functioning Autism is being phased out because it oversimplifies a complex condition and may carry stigmatizing or misleading connotations. Many experts now prefer describing individuals based on their support needsusing the DSM-5’s model:

  • Autism Level 3 for those who require very substantial support
  • Functional labels like “low” or “high” can mask the person’s strengths or challenges in different areas (e.g., someone may be nonverbal but highly intelligent)

Clinically accurate and respectful language helps promote better understanding and care.

This page provides general educational content and is not a substitute for professional medical advice. Always consult a licensed provider for diagnosis and treatment.

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