Background Functional imaging of striatal dopamine transporters (DaT) is abnormal at presentation in Parkinson's disease (PD). While there is a cross-sectional relationship between the severity of bradykinesia and rigidity, and the degree of DaT loss, prospective studies have not been conducted.

Aim To assess for correlation between dopaminergic deficiency on FP-CIT SPECT and motor symptoms and complications after 3 years.

Methods Patients with PD, abnormal baseline FP-CIT SPECT and at least 3 years clinical follow-up were classified as: akinetic-rigid, tremor-dominant, or mixed. UPDRS-III motor scores at baseline and 3 years, and time-to-onset of motor complications were recorded.

Results 42 patients, 63% male, median age at onset 61.6 years (IQR 52.5–69.1) were included. Motor complications were seen in 54.7% (21.4% motor fluctuations, 11.9% dyskinesias, 21.4% combination). Clinical subtypes: seven tremor-dominant, 17 akinetic-rigid and 18 mixed. FP-CIT uptake was inversely correlated with 3 year UPDRS-III only for akinetic-rigid patients (r= −0.51, p=0.04). Time-to-onset of motor complications was inversely correlated with UPDRS-III subscores for bradykinesia and rigidity at baseline (r= −0.52, p=0.02) and at 3 years (r= −0.54, p=0.01).

Conclusion The degree of dopaminergic deficiency on FP-CIT SPECT correlates with worse motor status, and the development and severity of complications, after 3 years in akinetic-rigid PD patients.