Prognostic significance of weight changes in Parkinson's disease: the Park-weight phenotype.

Neurodegenerative Parkinson's disease (PD) is associated with a changing profile of weight as the disease advances. Whilst some patients gain weight, a significant proportion of patients lose weight. PD patients have a lower body weight as compared with non-PD controls. Weight loss is not a benign phenomenon. Patients with lower initial body weight and weight losers have a higher risk of developing dyskinesia. There is a relationship between body weight and levodopa dose, patients with higher levodopa dose per kilogram are at a higher risk of dyskinesia, the risk escalates above 6 mg per kilogram. Lower weight patients have risk of undernutrition and the associated disease pathology due to frailty. Weight losers are at risk of higher mortality and poor quality of life. PD patients should be assessed for body weight and the dose of levodopa be adjusted according to periodic weight changes, supplemented by other dopaminergic medications. Patients at risk of weight loss may be identified by their severe loss of olfaction since there seems to exist the olfaction-weight-dyskinesia phenotype. Measures should be taken to prevent weight loss in at-risk patients to prevent low-weight-related adverse outcomes in PD patients. These measures may protect PD patients from motor and non-motor adverse effects as the disease advances.