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Center for Autism and Developmental Disabilities Definitions and Signs & Symptoms

Definitions and Signs & Symptoms


What are Developmental Disabilities?
Developmental disabilities are a group of conditions that begin at birth or during childhood. These conditions are chronic and impact an individual throughout their lifetime. Often, these difficulties occur in several important life activities such as self-care, learning, physical movement, speaking and understanding language. The most common developmental disabilities are autism and intellectual disabilities.

What is Autism Spectrum Disorder?
Autism spectrum disorder is a developmental disorder that typically appears during the first two years of life. It affects brain function, specifically the areas of socialization, communication and repetitive behaviors. Autism is known as a spectrum disorder because it affects individuals in a variety of ways.

What are Intellectual Disabilities?
An intellectual disability is a developmental disorder that originates before the age of 18. Individuals have significant limitations in their intellectual functioning and adaptive behavior. Intellectual functioning is also known as intelligence and refers to how a person learns, reasons and problem solves. Adaptive behavior refers to skills learned and performed by people in their everyday lives such as self-care, following rules and being aware of safety risks.

Signs and Symptoms

A person with developmental disabilities such as autism or intellectual disabilities may show some or all of the following symptoms:

  • Delayed or no speech
  • Delays in meeting milestones
  • Poor eye contact
  • Limited facial expressions
  • Odd hand and body movements
  • Unusual reactions to noise, textures and smells
  • Becoming upset by changes or new things
  • Little or no pretending
  • Little or no pointing, clapping or waving
  • Limited imitation of others
  • Limited interest in others
  • Unusual tone of voice or noises
  • Repetitive behaviors and sounds