失憶型輕度認知障礙族群要旨與細節記憶衰退之差異性

Abstract

研究顯示，失憶型輕度認知障礙症患者比正常老化的高齡者有較高的風險發展出失智症，而及早辨識出高風險群，有助於延緩失智症發生。認知障礙症患者早期腦病灶多位於內側顳葉結構，這些腦區與記憶功能息息相關。研究顯示透過量測情節記憶表現，可以協助區辨失智症高風險群。雖然事件記憶又可分成細節記憶與要旨記憶，然而我們並不了解失憶型輕度認知障礙患者，是否在兩種記憶類型有同等程度的缺損。為此我們招募了失憶型輕度認知障礙症長者，並長時間追蹤其細節記憶與要旨記憶的記憶表現。我們也檢視在學習階段同步提供視覺訊息，是否能夠提升患者的記憶表現。結果顯示，失憶型輕度認知障礙長者在細節記憶與要旨記憶表現均低於正常老年人，然而相比於細節記憶，要旨記憶更能區分兩者間的記憶表現。此外，在學習過程同時提供聽覺與視覺訊息，能夠提升患者的記憶表現，且相比於單一聽覺訊息，同時呈現視聽覺訊息，與內側顳頁結構有更強的關聯性。總結來說，我們研究發現區分不同的記憶種類有助於辨識失智症高風險群，並且提供有效的記憶策略以增進患者記憶表現。

Amnestic mild cognitive impairment (aMCI) was a transitional state between normal aging and dementia and was regarded as a risk factor for dementia due to Alzheimer's disease. Medial temporal structures, critical for memory processing, are the earliest affected brain regions in patients with aMCI, and episodic memory performances have been a reliable way to discriminate patients with aMCI from normal adults. However, it remained unclear if memory for detailed and gist information decayed differently in patients with aMCI compared with cognitively normal older adults. This study examined the episodic memory performance in patients with aMCI over two weeks. Moreover, the effect of unisensory versus multisensory encoding on memory retention over time was investigated. The results revealed that compared with cognitively normal older adults, aMCI patients performed poorly in both detail and gist memory, and the performance gaps were long-lasting. Moreover, memory performances of patients with aMCI were enhanced by offering multisensory information, and the bimodal input was significantly associated with medial temporal structures. In conclusion, our findings indicated that fine-grand analysis of episodic memory was necessary for detecting individuals with a high risk of dementia. Multisensory materials may enhance memory performance in patients with aMCI.