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> the document you refer to is not attached it came on Raylin's message. here it is: Neuropathol Appl Neurobiol. 2007 Dec;33(6):599-614. Epub > 2007 Oct 24. > Parkinson's disease: a dual-hit hypothesis. > Hawkes CH, Del Tredici K, Braak H. > Essex Neuroscience Centre, Queen's Hospital, Romford, > Essex UK. > > Accumulating evidence suggests > that sporadic Parkinson's disease has a long prodromal period > during which several non-motor features develop, in particular, > impairment of olfaction, vagal dysfunction and sleep disorder. > Early sites of Lewy pathology are the olfactory bulb and enteric > plexus of the stomach. We propose that a neurotropic pathogen, > probably viral, enters the brain via two routes: (i) nasal, with > anterograde progression into the temporal lobe; and (ii) > gastric, secondary to swallowing of nasal secretions in saliva. > These secretions might contain a neurotropic pathogen that, > after penetration of the epithelial lining, could enter axons of > the Meissner's plexus and, via transsynaptic transmission, reach > the preganglionic parasympathetic motor neurones of the vagus > nerve. This would allow retrograde transport into the medulla > and, from here, into the pons and midbrain until the substantia > nigra is reached and typical aspects of disease commence. > Evidence for this theory from the perspective of olfactory and > autonomic dysfunction is reviewed, and the possible routes of > pathogenic invasion are considered. It is concluded that the > most parsimonious explanation for the initial events of sporadic > Parkinson's disease is pathogenic access to the brain through > the stomach and nose - hence the term 'dual-hit'. > maryse ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn