巴金森失智症與路易氏體失智症

Parkinson's Disease with Dementia and Dementia with Lewy Bodies

巴金森失智症和路易氏體失智症臨床特徵非常相似，包括認知功能障礙、行為異常、自律神經症狀和巴金森症候群。這2種疾病最大的差異在於臨床症狀出現的時間不同，現在以1年來區分；即認知障礙出現於錐體外徑症狀1年以後，則屬巴金森失智症，相反的如果認知障礙出現於錐體外徑症狀1年內或認知障礙出現早於錐體外徑症狀則為路易氏體失智症。病理學上兩者相同都有路易氏體積聚於皮質、邊緣系統、新皮質地區和腦幹。路易氏體失智症臨床診斷包括三大核心特徵如巴金森氏症、認知功能波動和視幻覺，以及三項建議特點，如（1）快速動眼期睡眠行為障礙、（2）嚴重的抗精神藥物敏感、（3）基底核之多巴胺載體影像吸收降低等。巴金森失智症雖然尚缺統一之共識基準，但最近已有建議之診斷標準。由於神經影像學和分子生物學的進步，對路易氏體失智症和巴金森失智症的致病機轉更加瞭解。病理變化上這兩種疾病也可伴隨著阿茲海默的病理變化如老人性斑塊，此現象使臨床症狀更具多樣性。此二種疾病的藥物治療與一般巴金森氏病和阿茲海默氏病的治療有很大的不同，需要臨床醫師更小心的鑑別診斷和使用藥物。

Patients with Parkinson's disease with dementia (PDD) or dementia with Lewy bodies (DLB) have similar clinical manifestations including cognitive impairment, behavior disorders, autonomic dysfunction, and parkinsonian features. The difference between these two disorders is based on the one year rule: PDD is diagnosed while the onset of dementia occurs 12 months or more after the onset of parkinsonism and DLB is diagnosed if cognitive impairment precedes or follows the parkinsonian features within 12 months. Both share the same pathological features including Lewy bodies in the cortex, limbic system, neocortical area and brainstem. The diagnostic criteria of DLB include three core features of parkinsonism, fluctuation of cognition, and visual hallucination. Three additional suggestive features include REM sleep behavior disorder, neuroleptic sensitivity, and an abnormal dopamine transporter scan. Although there is no formal consensus criteria for diagnosing PDD, a new clinical diagnostic criteria has been proposed by the Movement Disorder Society. With recent advances in neuroimaging and molecular biological studies, understanding of the pathogenetic mechanisms has become possible. In addition to the Lewy bodies in these two disorders, senile plaques with amyloid appear in both. With the combination of Lewy bodies and senile plaques deposition, the clinical features of PDD and DLB prove more complex, which leads to diagnostic challenges between these two disorders. Finally, the therapeutic approaches to PDD and DLB are different from the treatments for Alzheimer's disease and Parkinson's disease.