AUTHOR=Kobayashi Ryota , Hayashi Hiroshi , Kawakatsu Shinobu , Okamura Nobuyuki , Yoshioka Masanori , Otani Koichi 

TITLE=Assessment of Amyloid Deposition in Patients With Probable REM Sleep Behavior Disorder as a Prodromal Symptom of Dementia With Lewy Bodies Using PiB-PET

JOURNAL=Frontiers in Neurology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2019.00671

DOI=10.3389/fneur.2019.00671

ISSN=1664-2295

ABSTRACT=<p><bold>Introduction:</bold> Dementia with Lewy bodies (DLB) often exhibits REM sleep behavior disorder (RBD) at its prodromal stage. Meanwhile, DLB is often comorbid with Alzheimer's disease (AD)-type pathology. In typical AD, amyloid-β deposition begins considerably before the onset of dementia and has already reached a plateau at the stage of mild cognitive impairment. However, it is not known when amyloid accumulation starts in DLB with AD-type pathology. In the present study, we examined amyloid deposition in patients with RBD as a prodromal symptom of DLB using [11C]-Pittsburgh compound B positron emission tomography (PiB-PET).</p><p><bold>Methods:</bold> The subjects were 12 patients with probable RBD as diagnosed by the Japanese RBD screening questionnaire. They also showed abnormality in 123I-metaiodobenzylguanidine myocardial scintigraphy, a biomarker for DLB. For comparison, 11 patients with probable DLB were included. Applying PMOD software to the PiB-PET images, the global cortical distribution volume ratio was calculated and a ratio &gt;1.3 was regarded as PiB-positive.</p><p><bold>Results:</bold> Two of the RBD patients (16.7%) and eight of the DLB patients (72.7%) were PiB-positive. The amyloid-positive rate was significantly lower in the RBD group than in the DLB group (<italic>P</italic> = 0.012).</p><p><bold>Conclusion:</bold> The prevalence of amyloid deposition in RBD as a prodromal symptom of DLB was significantly lower than that in DLB, suggesting that amyloid accumulation does not always begin at the early stage of DLB.</p>