レヴィ小体型認知症—鑑別診断を中心に

Differential Diagnosis of Dementia with Lewy Bodies

レヴィ小体型認知症とアルツハイマー病との鑑別点は，前者は記憶障害が軽度で，認知機能の変動，注意・遂行機能障害，視空間認知機能障害，幻視，うつ症状が強く，レム期睡眠行動異常症，パーキンソニズム，自律神経症状がみられることである。画像検査では，頭部MRIで内側側頭葉の萎縮が軽度で，脳血流シンチグラフィで後頭葉の血流低下が，MIBG心筋シンチグラフィでMIBG集積低下が，ドパミントランスポーター（DAT）シンチグラフィで線条体のDAT機能低下が認められることである。

Abstract

Kosaka and colleagues first reported dementia with Lewy bodies (DLB) in 1976. They have also established the concept of DLB. It is important to differentiate DLB from other dementia, especially Alzheimer disease (AD), because the medical treatment, management, and prognosis of DLB and AD are different. We have used several clinical features and imaging tools to differentiate between DLB and AD. With regard to clinical features, patients with DLB have relatively mild memory disturbances and fluctuating cognition. However, compared to patients with AD they have more severe disturbances of attention and executive, visuospatial functions, visual hallucination, depression, autonomic symptoms. In addition, they show the presence of REM sleep behavior disorder and idiopathic parkinsonism. On performing imaging analysis, patients with DLB showed milder atrophy in the medial temporal lobe on brain MRI, reduced occipital activity on SPECT or PET, reduced MIBG uptake on MIBG cardiac scintigraphy, and low dopamine transporter activity in the basal ganglia on SPECT or PET.