Abstract: An easily administered, non-invasive, sensitive and specific system and method for screening persons for dementia, particularly dementia of the Alzheimer's type, is provided. The system and method include means for irradiating the eye of a person with light, preferably light solely within the infrared spectrum, and means for generating a signal responsive to the amount of light reflected from the eye over a period of time. This signal is indicative of changes in the pupil's size over time. The system and method further include means for performing a Fourier transform upon this signal to provide a value indicative of the strength of this signal's frequency components. This value then is compared against a predetermined threshold value and, if this threshold value is exceeded, a higher probability is assigned to the person having dementia, particularly dementia of the Alzheimer's type.