How is IDD diagnosed?

A diagnosis of Intellectual and Developmental Disabilities (IDD) is made through a combination of assessments.

To be diagnosed with an intellectual disability, a person must have:

• sub-average intellectual functioning
• significant limitations in adaptive behavior in one or more of the following areas: conceptual, social, or practical skills.
• onset of the condition before the age of 22.

Intellectual functioning is evaluated using IQ tests. Adaptive behavior is assessed through standardized tools like the Adaptive Behavior Assessment System (ABAS), which looks at an individual's ability to understand social cues, communicate clearly, manage basic self-care tasks or chores, and perform daily activities.

Feedback from parents, teachers, and others who regularly interact with the child is also often used to assess adaptive skills.

Early identification of IDD is essential. It opens the door to timely intervention, support, and skill-building strategies that can help individuals lead more independent and fulfilling lives.