[Relationship between striatal ¹²³I-FP-CIT uptake and cognitive functions in Parkinson's disease]

We studied whether ¹²³I-FP-CIT uptake in the striatum correlates with cognitive performance in patients with Parkinson's disease (PD). Sixty-nine patients with PD (24 men and 45 women, average age = 71.3 years, disease duration = 5.2 years) underwent ¹²³I-FP-CIT SPECT and neuropsychiatric measurements. Cognitive performance was assessed using the MMSE (Mini-mental state examination), TMT (Trail making test), MoCA-J (Japanese version of Montreal cognitive assessment), FAB (Frontal assessment battery), ACE-R (Addenbrooke's cognitive examination revised), BDI-II (Beck depression inventory-II), and RBMT (Rivermead behavioural memory test) in the ON state. The average specific binding ratio (SBR) and AI (Asymmetry index) of striatal ¹²³I-FP-CIT uptake were semi-quantitatively measured using DaTView software. Clinical data and SBR were compared. In addition, participants were divided into four groups according to the visibility of the striatum on ¹²³I-FP-CIT SPECT images, and results of the Eagle Wing (EW) group and the Egg shape (ES) group were compared. SBR was negatively correlated with age (P < 0.001), disease duration (P < 0.001), H-Y stage (P < 0.001), levodopa equivalent dose (P = 0.004), TMT-A (P = 0.001), and TMT-B (P < 0.001), and positively correlated with MMSE (P = 0.021) and FAB (P = 0.029), MoCA-J (P = 0.012)，RBMT (P = 0.021). Multiple regression analysis confirmed that age (P = 0.016) and FAB (P = 0.035) were independent predictors for SBR. Furthermore, in the ES group, Movement Disorder Society - Unified Parkinson's disease rating scale part III scores were significantly higher (P = 0.013) and the AI was lower (P < 0.001) than those in the EW group. Conversely, there were no differences in the findings of neuropsychiatric measures between the two groups. Our study results demonstrate that imaging with ¹²³I-FP-CIT SPECT is sensitive for detecting dopaminergic deficits associated with frontal lobe functions in patients with PD.