id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-262281-56tbrl8a	Hawkes, C. H.	Parkinson's disease: a dual‐hit hypothesis	2007-10-24		.txt	text/plain	8191	387	41	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. Additional studies not only have corroborated the initial involvement of anterior olfactory structures, but also have pointed to an early involvement of the enteric nerve cell plexuses as well as of the dorsal motor nucleus of the vagus and the intermediate reticular zone in the lower brainstem [21] [22] [23] [24] [25] . The next sizeable investigations using the University of Pennsylvania Smell Identification Test (UPSIT) showed that age-matched olfactory dysfunction did not relate to odour type, was independent of disease duration, and did not correspond with motor function, tremor or cognition [31, 32] . Daniel and Hawkes [102] examined olfactory bulbs and tracts in eight controls as well as eight patients with a clinical and pathological diagnosis of PD taken from the United Kingdom Parkinson's Disease Brain Bank.	./cache/cord-262281-56tbrl8a.txt	./txt/cord-262281-56tbrl8a.txt