Early diagnosis of Parkinson's disease

In idiopathic Parkinson's disease (IPD) approximately 60 % of the nigrostriatal neurons of the substantia nigra (SN) are degenerated before neurologists can establish the diagnosis according to the widely accepted clinical diagnostic criteria. It is conceivable that neuroprotective therapy starting at such an ‘advanced stage’ of the disease will fail to stop the degenerative process. Therefore, the identification of patients at risk and at earlier stages of the disease appears to be essential for any successful neuroprotection. The discovery of several genetic mutations associated with IPD raises the possibility that these, or other biomarkers, of the disease may help to identify persons at risk of IPD. Transcranial ultrasound have shown susceptibility factors for IPD related to an increased iron load of the substantia nigra. In the early clinical phase, a number of motor and particularly non-motor signs emerge, which can be identified by the patients and physicians years before the diagnosis is made, notably olfactory dysfunction, depression, or ‘soft’ motor signs such as changes in handwriting, speech or reduced ambulatory arm motion. These signs of the early, prediagnostic phase of IPD can be detected by inexpensive and easy-to-administer tests. As one single instrument will not be sensitive enough, a battery of tests has to be composed measuring independent parameters of the incipient disease. Subjects with abnormal findings in this test battery should than be submitted to nuclear medicine examinations to quantify the extent of dopaminergic injury and to reach the goal of a reliable, early diagnosis.