Definition: Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
Input: It is well known that autonomic failure is severer in patients with dementia with Lewy bodies (DLB) compared with patients with Parkinson's disease (PD). According to the Braak's hypothesis, Lewy bodies first appear in the olfactory bulb or peripheral autonomic nervous system. Lewy bodies in the peripheral autonomic nervous system ascend to dorsal motor nuclei of vagus nerve, while those in the olfactory bulb expand to the limbic system. Lewy bodies later attain the substantia nigra. However, it seems that Braak staging can not explain difference in severity of autonomic failure between DLB and PD. As a possibility, in DLB patients with significant autonomic failure, Lewy bodies may have been localized to the peripheral autonomic nervous system in a long time before onset of dementia or parkinsonism, and propagation of Lewy bodies into the central nervous system may be initiated by apparition of certain promotion factor, such as ageing and amyloid-.
