What is defined by onset in the developmental period before the age of 22 years?

The concept of "onset in the developmental period before the age of 22 years" is particularly aligned with the definition of intellectual disability. Intellectual disability is characterized by limitations in both intellectual functioning and adaptive behavior, which originate during the developmental period. This means that the symptoms and challenges should be evident before the individual turns 22 and typically manifest before the age of 18.

In this case, the focus on onset during the developmental years emphasizes that conditions such as intellectual disability are identified early in life, which is critical for intervention and support. The criteria for identifying intellectual disabilities are rooted in assessments of cognitive abilities and day-to-day functioning, allowing for tailored interventions to improve the individual’s quality of life and adaptability.

Though other options may involve onset in early developmental stages, they do not adhere as strictly to the age cutoff of 22 years. For example, while autism spectrum disorder and language disorders may also present in early childhood, they encompass a broader range of symptoms and don't necessarily have the same emphasis on cognitive limitations as a defining component.