The Effects of Normal Aging, Subjective Cognitive Decline, Mild Cognitive Impairment, or Alzheimer's Disease on...

Alzheimer's disease (AD) has been confirmed as an influencing factor of visual impairment, but potential concomitant effects on visual and cognitive performance are not well understood.

To provide a new method for early screening of Alzheimer's disease and further explore the theoretical mechanism of the decline of whole visual and cognitive performance in AD.

We studied 60 individuals without dementia as normal control (NC), 74 individuals with subjective cognitive decline (SCD), 60 individuals with amnesia mild cognitive impairment (aMCI), and 75 patients with AD on a battery of tests designed to measure multiple aspects of basic and higher-order visual perception and cognition. All subjects performed on same visual and cognitive test batteries.

The results showed both of four groups, with the stimulus-presentation time being longer, the visual-search performance improved, and both the eye interest-area first fixation duration and the interest-area-fixation count increased. Particularly under the noise-masking condition, the AD group performed the worst at stimulus-presentation times between 300 and 900 ms. The aMCI group, but not the SCD group, performed worse than the NC group at the stimulus-presentation time of either 300 or 500 ms. The interest-area-fixation count was higher in all the patient groups than that in the NC group, and distinguishable between participants with AD and those with SCD or aMCI.

The visual-search performance combined with eye-movement tracking under the noise-masking condition can be used for distinguishing AD from normal aging, SCD, and aMCI.