Alzheimer's disease (AD) is a common, devastating form of
dementia. With the advent of promising symptomatic treatment, the
importance of recognizing AD at its very earliest stages has increased. We
review the extant neuropsychological and neuroimaging literature on
preclinical AD, focusing on longitudinal studies of initially nondemented
individuals and cross-sectional investigations comparing at-risk with
normal individuals. We systematically reviewed 91 studies of
neuropsychological functioning, structural neuroimaging, or functional
neuroimaging in preclinical AD. The neuropsychological studies indicated
that preclinical AD might be characterized by subtle deficits in a broad
range of neuropsychological domains, particularly in attention, learning
and memory, executive functioning, processing speed, and language. Recent
findings from neuroimaging research suggest that volume loss and cerebral
blood flow or metabolic changes, particularly in the temporal lobe, may be
detected before the onset of dementia. There exist several markers of a
preclinical period of AD, in which specific cognitive and biochemical
changes precede the clinical manifestations. The preclinical indicators of
AD reflect early compromise of generalized brain integrity and temporal
lobe functioning in particular. (JINS, 2006, 12,
707–735.)