Which of the following is classified as a disorder of the nervous system?

Alzheimer's disease is classified as a disorder of the nervous system because it primarily affects the brain and involves the degeneration and death of brain cells. This progressive neurological condition leads to issues with memory, thinking, and behavior, distinctly impacting cognitive functions. It is characterized by the buildup of amyloid plaques and tau tangles in the brain, which interfere with neuronal communication and lead to the symptoms associated with dementia.

In contrast, heart disease primarily affects the cardiovascular system, diabetes is an endocrine disorder related to insulin deficiency or resistance, and arthritis primarily involves the joints and is classified as a musculoskeletal disorder. Thus, Alzheimer's disease stands out as a specific neurological disorder, emphasizing its classification within the nervous system.