Behavioral economics calls into question the central assumption of classical economics: that individuals are rational actors who seek to maximize their self-interest.

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The big remaining question for the scientists is whether these behavioral differences are detectable in an fMRI machine.

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"It is likely to play an important role in learning both how to diagnose and treat the disease, but it's still an open question at this point for asymptomatic people, " said Dr. Park, a behavioral and brain-sciences professor who uses Amyvid in her research on aging of healthy older adults.

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