A prospective evaluation of taste in Parkinson's disease

It is well known that Parkinson's disease is characterized by a variety of non-motor symptoms. A gustatory deficit is hypothesized to be one of them although few and only cross-sectional studies are available. The aim of our pilot study was to prospectively investigate the taste function in Parkinson's disease patients after some years from the first evaluation (mean follow-up 4.35 +/- 0.49 years; time range 3.5-5.6 years). A group of 26 patients was re-examined (16 males and 10 females; mean age 70.9 +/- 8.4 years, range 54-88 years). Taste function was assessed in one session, by means of the Whole Mouth Test (WMT) and Taste Strips Test (TST). Olfaction was also evaluated with the Sniffin' Sticks Identification Test (SST). All these tests are commercially available (Burghart Company, Germany). All patients were able to understand and complete the procedure. Although scores decreased over time, no significant difference was found between global taste scores of first and second evaluation, neither comparing every single taste quality (WMT: p = 0.234, Mann-Whitney U test; TST: p = 0.747, Mann-Whitney U test; McNemar chi-square in the range of 0-1.455). These results confirm a persistent but slight and stable taste impairment, in patients with Parkinson's disease. Future studies on a much larger sample of patients are certainly required.