All the following are the major categories of psychological...

Autism spectrum disorder, Attention Deficit Hyperactivity Disorder, and Intellectual disability are classified primarily as neurodevelopmental disorders, which are a major category of psychological disorders according to standard diagnostic manuals like the DSM-5.

Alzheimer's disease, however, is fundamentally categorized as a neurocognitive disorder, primarily involving progressive neurodegeneration and loss of cognitive functioning, usually affecting older adults.

While it has profound psychological impacts, it is fundamentally a degenerative disease of the brain rather than a primary psychological disorder.

Answer: Alzheimer's disease.