Ferman, Tanis J.

AbstractIntroductionRapid eye movement sleep behavior disorder (RBD) is strongly associated with synucleinopathies. In 2012, we reported an increased risk of mild cognitive impairment (MCI) and Parkinson disease (PD) in cognitively normal Olmsted County, Minnesota, residents, aged 70 to 89 years with probable RBD. Here, we examine their progression to dementia and other neurodegenerative phenotypes.MethodsFifteen participants with RBD who were diagnosed with either MCI or PD were longitudinally followed, and their subsequent clinical courses were reviewed.ResultsOver 6.4 ± 2.9 years, six of the 14 participants with MCI developed additional neurodegenerative signs, five of whom had Lewy body disease features. Four of them progressed to dementia at a mean age 84.8 ± 4.9 years, three of whom met the criteria for probable dementia with Lewy bodies. One subject with PD developed MCI, but not dementia.DiscussionOur findings from the population‐based sample of Olmsted County, Minnesota, residents suggest that a substantial number of RBD patients tend to develop overt synucleinopathy features over time, and RBD patients who develop MCI and subsequent dementia have clinical features most consistent with dementia with Lewy bodies.

ObjectivePatients with probable dementia with Lewy bodies (DLB) often have Alzheimer's disease (AD)‐related pathology. Our objective was to determine the pattern of positron emission tomography (PET) tau tracer AV‐1451 uptake in patients with probable DLB, compared to AD, and its relationship to β‐amyloid deposition on PET.MethodsConsecutive patients with clinically probable DLB (n = 19) from the Mayo Clinic Alzheimer's Disease Research Center underwent magnetic resonance imaging, AV‐1451, and Pittsburgh compound‐B (PiB) PET examinations. Age‐ and sex‐matched groups of AD dementia (n = 19) patients and clinically normal controls (n = 95) from an epidemiological cohort served as a comparison groups. Atlas‐ and voxel‐based analyses were performed.ResultsThe AD dementia group had significantly higher AV‐1451 uptake than the probable DLB group, and medial temporal uptake completely distinguished AD dementia from probable DLB. Patients with probable DLB had greater AV‐1451 uptake in the posterior temporoparietal and occipital cortex compared to clinically normal controls, and in probable DLB, the uptake in these regions correlated with global cortical PiB uptake (Spearman rho = 0.63; p = 0.006).InterpretationMedial temporal lobe AV‐1451 uptake distinguishes AD dementia from probable DLB, which may be useful for differential diagnosis. Elevated posterior temporoparietal and occipital AV‐1451 uptake in probable DLB and its association with global cortical PiB uptake suggest an atypical pattern of tau deposition in DLB. ANN NEUROL 2017;81:58–67