title: Altered categorization of semantic knowledge in Korean patients with Alzheimer's disease.
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.
authors.affiliation: Department of Neuropsychiatry, Seoul National University Bundang Hospital, Bundang-Gu, Seongnam, Gyeonggi, Republic of Korea.
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Chang
authors.forename: Yeon Kyung
authors.initials: YK
authors.lastname: Chi
authors.forename: Ji Won
authors.initials: JW
authors.lastname: Han
authors.forename: Tae Hui
authors.initials: TH
authors.lastname: Kim
authors.forename: Jong Chul
authors.initials: JC
authors.lastname: Youn
authors.forename: Seok Bum
authors.initials: SB
authors.lastname: Lee
authors.forename: Joon Hyuk
authors.initials: JH
authors.lastname: Park
authors.forename: Jung Jae
authors.initials: JJ
authors.lastname: Lee
authors.forename: Kyooseob
authors.initials: K
authors.lastname: Ha
authors.forename: Ki Woong
authors.initials: KW
authors.lastname: Kim
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000523:psychology*; D016022:Case-Control Studies; D003071:Cognition; D003210:Concept Formation; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D056910:Republic of Korea; D012660:Semantics