What is not included in the definition of developmental disability?

The definition of developmental disability generally encompasses a range of conditions that affect an individual's development and functioning over a sustained period. These disabilities typically manifest during the developmental period and may include conditions like cerebral palsy, autism spectrum disorders, and intellectual disabilities, all of which occur in childhood and can result in substantial limitations in daily life activities.

Dementia, particularly when it arises from a degenerative brain disorder, is characterized more as a cognitive decline that typically occurs later in life rather than during the developmental stages. It does not fall under the category of developmental disabilities since it usually occurs after the critical developmental period and is primarily viewed as a result of aging or disease processes that affect the brain. Thus, it does not align with the developmental disabilities category, which is why it is accurately identified as not being included in the definition.