Relationship between I123-Ioflupane binding in striatal dopamine transporters and depression in Parkinson’s disease: A SPECT study

Abstract

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Objectives: To investigate the relationship between depression and asymmetry of striatal dopamine transporter (DAT) density in vivo by mean of I123-Ioflupane brain SPECT in patients with Parkinson’s disease (PD) with or without concomitant depression. Methods: SPECT brain studies were obtained in PD patients 3 hours after administration of I123-Ioflupane (130 MBq) by mean of a dedicated gammacamera (Prism 3000, Philips). I123-Ioflupane specific striatal uptake (ISSU) and asymmetry index [AI:(ISSU right - ISSU left)/(ISSU right + ISSU left)] were calculated, after iterative section reconstruction (OS-EM algorithm)and filtering and reorientation of SPECT sections, in a 2.56 cm section including striatal structures and occipital cortex, as aspecific reference. 10 PD patients with AI values <5% (sPD; 5 males; age 68±5 yrs; duration <3 yrs; H&Y stage I-II; UPDRS-III 18±15) and 10 PD patients with AI >15% (aPD: age 65±4 yrs; duration <3 years; H&Y stage I-II; UPDRS-III 19±10)were included. No PD patient was demented (MMSE score>25). The Beck Depression Inventory (BDI) was used to quantify the severity of depression. We further compared ISSU values of patients with a BDI score under 5 (ndPD; 9 patients; age 65±4 yrs; UPDRS-III 17±11; BDI mean score 3±1) and patients with a score over 10 (dPD; 6 patients; age 67±6 yrs; UPDRS-III 20±19SD; BDI score 15±7). Results: No difference was found for BDI score between sPD and aPD. No difference was also found between ndPD and dPD mean ISSU values. However, we found more symmetric and bilateral DAT decrement in dPD (AI striatum, p<0.05; AI caudate nucleus, p<0.01; AI putamen, p=0.05). DBI score also correlated with AI of caudate nuclei (Pearson test, p<0.05) and left caudate nucleus ISSU value (Pearson test, p<0.05). Conclusions: Depression in PD might be associated with a more symmetric and bilateral pre-synaptic striatal damage, as assessed by I123-Ioflupane SPECT, and related to DAT impairment in caudate nucleus.