Early diagnosis in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder clinically characterised by motor symptoms, and these manifestations arise after an extensive loss of dopaminergic neurons in the substantia nigra. In the last decades evidence has emerged to show that the onset of neurodegeneration in PD probably begins many years before the onset of motor symptoms. Additionally non-motor manifestations, such as olfactory dysfunction, REM behavioural disorder, depression and constipation, also arise earlier than motor manifestations in the course of the disease. Neuroimages are useful in identifying subjects at risk of developing PD, as the result of early non-motor manifestations, or carriers of genetic mutations associated with familial PD. In this article we review the available evidence in diagnosing PD in the early non-motor stage and how this approach could help us to improve the treatment of PD patients.