Hyposmia and Executive Dysfunction as Predictors of Future Parkinson's Disease: A Prospective Study

Olfactory deficits and executive dysfunction are early and common symptoms in Parkinson's disease (PD). Previous studies have shown that hyposmia can be a first sign of PD. The aim of the present study was to determine which of three olfactory tests and two selected tests of executive function would be the best predictor of future PD over,1 5 year period. In a cohort of 361 non-parkinsonian. non-demented first-degree relatives of PD patients, in whom alternative causes of olfactory dysfunction were excluded, we measured baseline performance oil three olfactory and two executive function tasks. Five years front baseline, clinical neurological evaluation and/or a screening questionnaire, sensitive to the presence of Parkinsonism were used to detect individuals developing clinical PD. Our results show that in first degree relatives of PD patients worse performance oil each of three olfactory processing tasks was associated with an increased risk of developing PD within 5 years, whereas performance on selected test,, of executive dysfunction was not associated with an increased risk of developing PD. Interestingly, impaired odor discrimination was the best predictor for future PD. 9 2009 Movement