Background: Using dual time F-18 FP-CIT, we evaluated cortical perfusion, striatal binding and neuropsychological performance simultaneously in Parkinson disease (PD) with and without mild cognitive impairment (MCI), to investigate neural correlates between caudate and frontal cortex.
Methods: According to the neuropsychological scores, subjects were classified into 26 healthy controls (HC), 38 PD-MCI (executive) (PE), 24 PD-MCI (non-executive) (PN) and 21 PD (motor) (PM). Scans were acquired at 10 minutes and 2 hours. Group differences of early perfusion and delayed binding were compared using SPM and volume of interest method. The relationships between neuropsychological variables and the striatal binding were investigated with correlation and regression analysis.
Results: Compared with PM, PE showed decreased prefrontal perfusion and binding of both caudates (right: P=0.0010, left: P=0.014), but not of both putamens. Compared with PN, PE showed decreased binding of both caudates (right: P=0.001, left: P=0.005), but not in both putamens. Binding of both caudates correlated with the Stroop z-score, but not of both putamens. Executive score was a contributing factor to binding of the caudate, and not the putamen.
Conclusions: PE showed decreased prefrontal perfusion and caudate binding, supporting neural correlates between the caudate and the prefrontal cortex. Dopaminergic binding of the caudate, but not of the putamen, was related to executive scores. Caudate hypofunction was specific to executive domain. This is the first study that elucidated the clinical use of dual time F-18 FP-CIT for integrative evaluation of cognitive and motor function in PD.