Olfaction, dyskinesia and profile of weight change in Parkinson's disease: Identifying neurodegenerative phenotypes

ObjectivesTo study the relationship between olfaction and body weight profile in Parkinson's disease.MethodsProspective assessment of 99 PD patients for clinical parameters, olfaction using UPSIT and current and previous body weight. Patients were categorised as weight losers (WL) and non-weight losers (NWL) depending on change of weight from previous years. Olfaction was categorised into two groups at the cut-off of the median level of UPSIT scores. Data was analysed to study the relationship of olfaction on weight change.ResultsThirty-nine were weight losers (WL) and 60 non-weight losers (NWL). WL were significantly older (p = 0.02), females (p = 0.03) and had more severe impairment of olfaction, UPSIT 15 ± 4 vs 19 ± 5; p < 0.004. Patients with more severe olfaction (anosmic) impairment were older (p = 0.001) and had significantly lower weight, 75 vs 83 kg, p = 0.01. There was no difference in the proportion of smokers, medication usage, difficult swallowing or calorie consumption in any group. Weight losers and severe olfaction loss were associated with more severe H&Y stage. Patients below the median-UPSIT (anosmic) had lost weight during the previous years whereas those above the median (hyposmic) had gained weight. Regression analysis revealed UPSIT at the median level to be the most significant variable (p < 0.001) for weight loss. There was continuous loss of olfaction with increasing disease severity. Higher olfactory loss was associated with higher risk of dyskinesia.ConclusionEarly assessment of olfaction may identify patients of different phenotypes for weight change and risk of dyskinesia during the course of the disease.