Biology

Alzheimer's is primarily a neurodegenerative disorder that affects memory, thinking, and behavior. While it may eventually lead to some motor symptoms as the disease progresses, its main characteristics are cognitive decline such as memory loss, confusion, and problems with language and judgment.

The other options are incorrect:

Huntington's is a genetic neurodegenerative disorder that causes involuntary movements (chorea), cognitive decline, and psychiatric problems. While it does cause cognitive decline, it is not the most common cause of dementia among older adults. It is caused by an inherited mutation in the HTT gene.