| Summary: | 碩士 === 國立成功大學 === 行為醫學研究所 === 99 === Alzheimer’s disease (AD) is a common degenerative disease among elders. According to previous researches, about half of the population of AD patients suffered from topographical disorientation, and often experienced a loss of direction in familiar environments. Previous behavioral research have found that most early AD patients could recognize landmarks in their familiar surroundings, and some AD patients could construct maps of the areas where they had gotten lost, indicating that AD patients might experience getting lost despite their ability to preserve memories of landmarks and maps.
Mental rotation is the ability to mentally rotate spatial representations in different perspectives. Normally, people can imagine themselves moving on a surfaced map and determine which way to turn through their ability of mental rotation. Previous studies showed that AD patients could not perceive themselves to walk on a surfaced map, indicating that their inability to determine the correct direction would be due to the degeneration of mental rotation ability, and this would be the reason why AD patients got lost despite their preserved memories of landmarks and maps.
The present study included forty early AD patients and twenty-two normal controls. This study further divided the AD patients into two groups according to the experiences of directional confusion in their daily life. Eighteen of the AD patients had not experienced directional confusion (AD-noDC) and twenty-two of them had (AD-DC). Right-left Orientation Test (RLOT), Figure Rotation Test (FRT), Money Road-map Test (MRMT) were used to assess their mental rotation ability. Virtual City Pointing Task (VC) was used to assess their ability to mentally rotate a map and make directional judgment.
The results showed that the early AD patients performed as well as the normal controls in all tests. Comparing AD-noDC with AD-DC, the AD-noDC participants performed as well as the AD-DC participants in RLOT, FRT and VC but worse than AD-DC in MRMT. The present study showed that the early AD patients still preserved the mental rotation ability, and the degeneration of mental rotation ability would not be a main reason for early AD patients to experience getting lost.
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