Olfactory function in Parkinson's Disease - effects of training.

BACKGROUND: Up to 90% of patients with Parkinson's disease (PD) exhibit olfactory dysfunction, but little is known about the effects of olfactory training. The study aim was to investigate whether the ability to identify olfactory stimuli can be improved by means of a brief training session. Furthermore, the impact of hyposmia on quality of life in PD was investigated by means of a questionnaire. METHODS: Olfactory function was rated in 34 patients with PD and in 26 controls before and after a training session. An additional 20 patients with PD served as a control group and were tested twice without an intervening training session. Long-term effects were evaluated in a small subset of patients. Cognitive tests and DaT SPECT scans were performed. RESULTS: We demonstrated significant same-day and long-term training effects in trained PD patients compared with non-trained PD patients. A slightly significant correlation was seen between the training effect and DaT putamen values, but not with cognitive test scores. Furthermore, patients with PD reported that hyposmia significantly decreased their quality of life. CONCLUSIONS: Patients with PD improved the number of correctly identified odors in an olfactory test through a brief training session. Olfactory training may have potential in rehabilitation of patients with PD.

Clinical heterogeneity in Parkinson's disease revisited: a latent profile analysis.

OBJECTIVE: The heterogeneity of Parkinson's disease (PD) is increasingly recognized, and several attempts have been made to subclassify subjects on clinical or cognitive features. We explored the utility of latent profile analysis (LPA) as a means of classifying patients with PD on clinical features and test validity of these subclasses against neuropsychological data. METHODS: LPA utilizing clinical variables while controlling for age was applied to a cohort of 71 outpatients with PD. The resultant subgroups were validated via comparison to 30 control subjects on neuropsychological tests of executive, memory, and visuospatial functions. RESULTS: The LPA resulted in a three-class solution identifying a 'younger onset, mild motor impairment group', a 'moderate motor impairment group', and an 'old onset, fast progression group'. The groups were distinguishable on cognitive variables with the 'younger onset mild motor impairment subgroup' displaying deficits pertaining verbal acquisition, visuospatial construction, and set maintenance. The 'moderate motor impairment group' exhibited widespread cognitive impairment, and the 'old onset, fast disease progression group' had extensive cognitive impairment but outperformed the former group on verbal acquisition and visuospatial function. CONCLUSION: LPA holds promise in PD research as it uncovered three PD subtypes distinguished by motor symptoms and disease progression and validated by cognitive variables.