Final answer:
Alzheimer's disease accounts for 70% of all dementia cases.
Step-by-step explanation:
Alzheimer's disease accounts for 70% of all cases of dementia. It is the most common cause of dementia in the elderly population. In 2012, an estimated 5.4 million Americans suffered from Alzheimer's disease, which is projected to increase to 13 million by the year 2050.