Alzheimer's Disease Research Today is a free monthly online journal that collates and summarizes the latest research about Alzheimer's Disease, including details on diagnosis, memory loss, heredity, treatment, medication.

Fast decay of iconic memory in observers with mild cognitive impairments.

Lu ZL, Neuse J, Madigan S, Dosher BA

Laboratory of Brain Processes, Department of Psychology, University of Southern California, Los Angeles, CA 90089-1061, USA. zhonglin@usc.edu

In a previous clinical report, unusually fast decay of iconic memory was obtained from a subject who later developed Alzheimer's disease. By using the partial-report paradigm, iconic memory (a form of visual sensory memory) in a group of observers with mild cognitive impairments (MCI) was characterized and compared with that of young college-age adults and older controls. Relatively long stimulus exposures were used for all three groups to ensure that older observers could perceive the stimuli. A set of conventional neuropsychological tests assessed cognitive functions of the MCI and older control groups. We found that iconic memory decayed much faster for observers with MCI than for normal controls, old or young, although the two groups of older observers performed at equivalent levels in precue tests (assay of visibility) and tests cued at long delays (assay of short-term memory). The result suggests that fast decay of iconic memory might be a general characteristic of observers with MCI who are at much higher than average risk of developing Alzheimer's disease later in life.

Published 2 February 2005 in Proc Natl Acad Sci U S A, 102(5): 1797-802.
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