| Summary: | 碩士 === 國立成功大學 === 行為醫學研究所 === 98 === Objective Many community-residing patients with Alzheimer disease (AD) have way-finding problems, particularly in the twilight, foggy or rainy days. In this study, we invited very mild AD patients and normal controls (NC) to test their recognition ability.
Methods The experimental samples included eight personally familiar and eight novel street scenes which were divided to Low Spatial Frequency (LSF) and Low Luminance (LL) conditions simulating nighttime, foggy or rainy days. Each was presented from the level 10 to level 1, representing the most difficult to the easiest. The participants were to judge whether the scene was familiar, and described how they did it. The accuracy was measured by number of scenes identified and the ability by the level needed.
Results Twenty AD and 20 NC subjects completed the study and their basic visual acuity was equal. The AD patients had poorer accuracy and ability to recognize familiar scenes in either LL or LSF condition. In familiar scenes section, AD patients tended to use global cues, a strategy often used by NC to judge novel scenes. This pattern indicates that these AD patients might treat their familiar scenes as novel. As the street scenes were becoming clearer or brighter, NC tended to use more cues as the accumulation rates were higher than those in AD, suggesting their possible impaired visual exploration skills and ineffective cue utilization.
Conclusion This study demonstrates that very mild AD patients have a poorer ability to recognize familiar environmental landmarks in LSF and LL conditions and probably due to impaired visual exploration skills and ineffective cue utilization.
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