Context Emerging data suggest that psychological and experiential factors are associated with risk of Alzheimer disease (AD), but the association of purpose in life with incident AD is unknown.

As far as researchers can tell, humans are the only animals subject to specific brain maladies such as Alzheimer's disease, which in the United States afflicts nearly 50% of people over the age of 85.

Conceivably, such delay could result in increased incidence of Alzheimer disease incidence in late old age.