Is pre-motor diagnosis possible? The European experience

The increasing knowledge about an ongoing neurodegenerative process long before the diagnosis of Parkinson's disease (PD) can be made according to the current diagnostic criteria urges the need for an earlier diagnosis with the final aim of neuromodulatory and neuroprotective therapies. A number of risk, pre-motor and early motor markers are being discussed as potential markers to identify individuals who will develop the full picture of clinical PD. In Europe, studies like the PRIPS study (Prospective validation of Risk factors for the development of Parkinson Syndromes) are performed to determine the sensitivity and predictive value of markers. In enriched risk cohorts like cohorts of individuals with RBD (Rem sleep Behaviour Disorder) or the TREND study (Tübinger evaluation of Risk factors for Early detection of NeuroDegeneration) specificity of markers is determined and further markers are evaluated. Moreover, progression of markers in the pre-motor period is being evaluated in these studies; for example, in the PMPP study (Progression Markers in the suspected Pre-motor Phase) assessments are performed at shorter time intervals. Establishing sensitivity, specificity, predictive value and progression of markers in yet healthy individuals are hoped to lay the basis for future interventional trials before the onset of motor-PD.