Final answer:
The most common cause of dementia is Alzheimer's disease, a neurodegenerative disorder that leads to memory loss, cognitive decline, and changes in behavior, affecting millions of Americans.
Step-by-step explanation:
The most common cause of dementia is C) Alzheimer's disease. Alzheimer's disease, initially studied by medical researcher Solomon Carter Fuller, is a neurodegenerative condition that affects memory, cognitive function, and behavior. It is characterized by the presence of amyloid plaques, neurofibrillary tangles, and a reduction in brain volume, specifically in the hippocampus which is severely affected in advanced cases. The symptoms of Alzheimer's include disruptive memory loss, confusion about time or place, and difficulty planning or executing tasks. According to estimates from 2012, approximately 5.4 million Americans suffered from Alzheimer's disease, and this number is projected to increase due to the aging of the baby-boomer generation.