High and low functioning autism are terms used to describe different ends of the autism spectrum based on the level of support an individual requires. While these are not formal medical diagnoses, they align with the DSM-5 severity levels for Autism Spectrum Disorder (ASD).

Low functioning autism, also referred to as level 3 or severe autism, represents the most significant challenges. Individuals in this category typically exhibit:

• Limited or no verbal communication skills, often relying on nonverbal gestures or assistive devices.
• A requirement for very substantial assistance with daily living tasks, such as eating, dressing, and self-care.
• Significant impairments in social interaction, often showing minimal engagement with others.
• Intense repetitive behaviors and extreme sensory sensitivities that can disrupt daily routines.

In contrast, high functioning autism (often associated with level 1) describes individuals who:

• Are usually verbal and may have advanced language skills, though they may struggle with social nuances.
• Can manage personal care and daily routines with minimal support.
• Desire social connections but face challenges in understanding social cues.

The primary distinction between the two is the intensity of support needed to navigate everyday life. While those with high functioning autism can often achieve a high degree of independence, individuals with low functioning autism require intensive, ongoing support and evidence-based interventions like Applied Behavior Analysis (ABA) to manage core deficits.