手段的日常生活活動（IADL）は認知機能に対し保護的に作用するのか—内側側頭葉の萎縮-認知機能-IADLの相互関連の検討

Is IADL a preventive factor in cognitive decline?: The interrelationships among medial temporal lobe atrophy, cognitive function and IADL

要旨：本研究は，アルツハイマー病，軽度認知障害，正常と診断された高齢者の合計107名を対象に，IADLが認知機能に対し保護因子となるか共分散構造分析にて検証した．その結果，年齢は認知機能に対し直接的な影響を認めず，年齢は内側側頭葉の萎縮を介して認知機能に影響を与えていた．また，内側側頭葉の萎縮は認知機能およびIADLの機能を低下させ，IADLの機能低下が認知機能の低下につながると解釈された．さらに，IADLの維持が認知機能の維持につながると解釈され，IADLが認知機能に対し保護因子になり得る可能性を示した．認知症予防や認知機能低下予防には，IADLに着目することが重要と考えられた．

　The purpose of this study was to assess the value of the Instrumental Activities of Daily Living (IADL) scale in preventing cognitive decline. The subjects were 107 patients. We developed a model in which the effects of medial temporal lobe atrophy on cognitive function are reflected indirectly through IADL. The model was evaluated using Structural Equation Modeling (SEM) analysis. The results indicated that age was not directly associated with cognitive function but rather indirectly based on medial temporal lobe atrophy. Moreover, medial temporal lobe atrophy was directly associated with both cognitive function and IADL, and influenced cognitive function indirectly through IADL. On the other hand, IADL was directly associated with cognitive function. This study illustrated the value of IADL as a measurement of cognitive dysfunction.