Alzheimer's disease is the most common form of dementing illness, affecting nearly 4.5 million Americans according to current estimates. The disease exhibits a strong association with old age, and is not commonly observed in individuals <65 years of age. Among individuals >65 years of age, the prevalence of Alzheimer's disease is ∼10%, and nearly half of all persons >85 years of age are affected by this condition. Given the apparent link between Alzheimer's risk and increasing age, as well as expected changes in the demographic structure of the United States population, it has been projected that the number of Americans with Alzheimer's disease will reach unprecedented levels in the coming years. In fact, it has been predicted that, barring the development of novel preventive therapies, the number of US residents with Alzheimer's will increase to 11–16 million by the year 2050.
The expected rise in the number of Alzheimer's disease cases represents a daunting challenge, due to the far-reaching negative impact of the disease. Alzheimer's disease is a condition that not only has profound effects on the affected patient but also takes a dramatic toll on the patient's primary caregiver, who is in many cases the spouse or an adult child of the patient. Patients with Alzheimer's experience cognitive and functional declines, often in association with behavioral disturbances, while caregivers frequently suffer reductions in quality of life attributable to the immense emotional, physical, and financial burdens associated with the task of providing care.