Affiliations: [a] Department of Neuropsychiatry, Seoul National University Bundang Hospital, Bundang-Gu, Seongnam, Gyeonggi, Republic of Korea | [b] Department of Neuropsychiatry, Kyunggi Provincial Hospital for the Elderly, Giheung-Gu, Yongin, Gyeonggi, Republic of Korea | [c] Department of Psychiatry, Dankook University Hospital, Cheonan, Chungcheongnam, Republic of Korea | [d] Department of Neuropsychiatry, Jeju National University Hospital, Jeju-si, Korea | [e] Department of Psychiatry, Kyungpook National University Hospital, Daegu, Korea | [f] Department of Psychiatry, Seoul National University College of Medicine, Jongno-Gu, Seoul, Republic of Korea
Correspondence:
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Correspondence to: Ki Woong Kim, M.D., Ph.D., Professor of Neuropsychiatry, Department of Neuropsychiatry, Seoul National University Bundang Hospital, 82 Gumi-Ro 173-Gil, Bundang-Gu, Seongnam, Gyeonggi 463-707, Republic of Korea. Tel.: +82 31 787 7432; Fax: +82 31 787 4058; E-mail: kwkimmd@snu.ac.kr.
Abstract: Decreased semantic memory has been suggested as an early sign in Alzheimer's disease (AD). This study aimed to investigate qualitative differences in semantic network between AD patients and healthy community-dwelling elderly controls. Category fluency test (animal) was administered to 416 AD patients and 339 controls. Mini-Mental State Examination was administered to evaluate global cognition. Patterns of semantic organization were compared between the two groups using hierarchical clustering (HC) and multidimensional scaling (MDS). In HC analysis, whereas a logically organized semantic structure was observed in the control group with an elaborate use of general knowledge, the semantic structure of the patient group was not interpretable. In MDS mapping, two dimensions of domesticity and size were identified in the control group. The MDS map of AD patients showed mixed features of perception and emotion. Knowledge-based semantic associations may be impaired in AD patients, which can add an extra dimension to cognitive impairments in AD patients regardless of quantitative facets of cognitive dysfunction.
