Two articles in previous, recent issues of this journal, reported the impact of biomarkers on the differential diagnosis of early Parkinson's disease (PD) by using two complementary tools. Kupsch et al1 reported that DaTscan single photon emission computed tomographhy imaging resulted in a change of diagnosis of clinically uncertain parkinsonian syndromes at 4 weeks in 45% of the patients versus 9% of the controls who did not receive the DaTscan, resulting in an increase in confidence of the diagnosis. This study adds credence to similar conclusions from previous studies2 ,3 by using an excellent design with prospective follow-up and inclusion of randomised control subjects who did not receive the DaTscan. However, there are several caveats in using this diagnostic test in routine …