Your nose may warn about onset of Parkinson’s

March 21st, 2008 - 12:18 pm ICT by admin  

Washington, March 21 (IANS) An impaired sense of smell occurs in the earliest stages of Parkinson’s disease (PD) and there is mounting evidence that it may precede motor symptoms by several years, according to a study. The study, by researchers at the Pacific Health Research Institute in Hawaii, found that smell impairment can precede the development of PD in men by at least four years.

Findings of the study have been published in the latest edition of the Annals of Neurology, the official journal of the American Neurological Association.

Led by G. Webster Ross of the VA Pacific Islands Health Care System and the Pacific Health Research Institute in Honolulu, Hawaii, the study included 2,267 men who received an olfactory test and were followed for up to eight years to find out if they developed PD. During the course of follow-up, 35 men developed the disease.

The results showed that a smell identification deficit could predate the development of PD by at least four years, although it was not a strong predictor beyond this time period.

A decreased ability to identify odours was associated with older age, smoking, more coffee consumption, less frequent bowel movements, lower cognitive function and excessive daytime sleepiness, but even after adjusting for these factors, those with poor odour identification had a five times greater risk of developing PD.

The pathology of smell impairment in PD is not completely understood, but nerve loss and the formation of Lewy bodies, abnormal clumps of proteins inside nerves cells that are thought to be a marker of PD, are known to take place in the olfactory structures of patients with the disease.

The authors note that one study involving brain dissection of dead patients with neurological disease found that olfactory structures are the earliest brain regions affected by Lewy degeneration, which supports the idea that an impaired sense of smell could be one of the earliest signs of the disease.

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