Amyloid-beta may contribute to the clinical presentation of dementia with Lewy bodies synergistically in the brain.

1072 Objectives: Comorbid beta-amyloid (A-beta) pathology is common in patients with dementia with Lewy body (DLB), which may indicate a synergistic interaction with Apha-synucleopathy (AS). The purpose of this study was to investigate possible association of A-beta with scintigraphic findings of cardiac sympathetic function in DLB patients. Methods: The study population included 21 patients with “probable DLB” based on the 4th consensus report of DLB Consortium. All underwent F-18 flutemtetamol (FMM) PET, to investigate cerebral A-beta positivity, which was correlated with scintigraphic biomarker of cardiac sympathetic function of I-123 metaiodobenzylguanidine (MIBG). Both visual and semi-quantitative results (early H/M: early phase heart to mediastinal ratio) were correlated with the FMM results. Results: Study population consisted with 17 women and 4 men, 78 ± 5 ranging from 68 to 89 years old. Median MMSE was 22 ranging from 12 to 27. FMM revealed positive A-beta in 10/21 patients. Positive A-beta did not associate with cognitive performance with MMSE (Positive: 21.5(18 - 27), Negative 24.05 (12 - 27), p = 0.56), nor with Age ( Positive: 77 (69 - 89) , Negative: 78 (68 - 84), p = 0.75 ). In contrast, positive A-beta significantly correlated with visually normal MIBG (table, p < 0.05) and higher early H/M (Positive: 2.7 ± 0.6, Negative: 2.2 ± 0.5, p < 0.05, Figure). Discussion: Process of AS may show a hierarchical pattern of upward sequence form (Braak hypothesis) or other patterns of amygdala- or cortical- predominant form (cerebral forms). The former form explains the clinical utility of I-123 MIBG for differential diagnosis of DLB because cardiac involvement of AS occurs in its early phase, while the other forms may not associate with MIBG abnormality. The results of the present study showed high prevalence of comorbid beta-amyloid (A-beta) pathology in cerebral forms supporting a synergistic effect of AS and A-beta pathologies in the brain. Conclusions: Clinically diagnosed “Probable DLB” patients demonstrated comorbid A-beta pathology in 50%. In particular, DLB patients with normal MIBG showed high prevalence of positive FMM, indicating cerebral forms of AS was associated with positive A-beta pathology. A-beta pathologies may contribute to the clinical presentation of DLB particularly in cerebral forms of AS. References: Braak H, Del Tredici K, Rub U, De Vos RAI, Steur ENHJ, Braak E. Staging of brain pathology related to sporadic Parkinson’s disease. Neurobiol Aging. 2003;24: 197-211. Zaccai J, Brayne C, McKeith I, Matthews F, Ince PG, MRC Cognitive Function, Ageing Neuropathology Study. Patterns and stages of alpha-synucleinopathy: Relevance in a population-based cohort. Neurology. 2008;70: 1042-1048.