Bayesian diagnostic approaches have been proposed by the Movement Disorder Society to standardise the process of clinically separating Parkinson’s disease (PD) from Parkinson-related disorders. In addition the same approach has been suggested in the pre-diagnostic identification of future PD patients based on prior probabilities of known risk factors. The onset of PD can be years, maybe decades, before the cardinal signs of the disorder manifest. The challenge is to identify early features and factors that can be used to identify those at risk of developing PD in this prediagnostic stage of the disorder. An understanding of basal ganglia function and how malfunction may lead to the vast symptomatology in PD is of paramount importance in regard to management approaches. In PD the ability to automate becomes disrupted due to dopamine loss in the striatum and its associated and progressive denervation changes.