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-β.