Objective: To evaluate whether the ¹²³I-FP-CIT striatal uptake differs in Parkinson’s disease (PD) drug-naïve patients with and without sexual dysfunction.

Background: Sexual dysfunction is one of the most disabling yet poorly investigated non-motor symptoms in PD [1]. Even though dopaminergic mechanisms have been involved in the pathogenesis, evidence from dopaminergic imaging studies is still lacking.

Method: 20 drug-naïve newly diagnosed patients (9 females and 11 males, aged 66.4±7.8 years) underwent ¹²³I-FP-CIT SPECT and complete motor and non-motor symptoms evaluation through UPDRS-III score, H&Y staging, Mini-Mental State Examination (MMSE), Addenbrooke’s Cognitive Examination (ACE), Beck Depression Inventory (BDI)-II, Zung’s Anxiety Scale, and Non-Motor Symptoms Scale (NMSS). During regular follow-up visits, a diagnosis of idiopathic PD was established for all patients according to current criteria. Based on NMSS sexual function scores, we identified patients with (WSC, score ≥1 ) and without (NoSC, score=0) sexual concerns. The ratios of striatal to occipital binding for the entire striatum (tSBR), putamina, and caudate were calculated using BasGan software [2].

Results: 8 WSC and 12 NoSC were identified. No statistically significant differences were found among groups regarding gender, age, H&Y, UPDRS-III, disease duration, scores in MMSE, ACE, Zung, BDI-II, and use of antidepressants. DATSCAN analysis revealed that WSC display significantly lower uptake values in the entire striatum (p=0.035) and in both putamina (p=0.029, p=0.023), whereas no differences were found in the caudate uptake [table1]. An exploratory logistic regression analysis with the backward stepwise method was conducted using significant DATSCAN variables. We found that the highest likelihood of sexual dysfunction occurrence was associated with decreasing uptake values in the least affected putamen (Odds Ratio=0.062, 95% CI 0.004-0.923, p=0.044).

Conclusion: To the best of our knowledge, this is the first study exploring striatal DAT binding in relation to sexual symptoms in PD. These findings further suggest that nigrostriatal system denervation (especially involving the putamina) is a key feature of PD altered sexual behavior, probably by disrupting the connections to the medial preoptic area, the paraventricular nucleus, and the nucleus accumbens.

References: [1] Meco G, Rubino A, Caravona N, Valente M. Sexual dysfunction in Parkinson’s disease. Parkinsonism Relat Disord. 2008 Aug;14(6):451-6. doi: 10.1016/j.parkreldis.2007.10.008. Epub 2008 Mar 3. PMID: 18316235. [2] Calvini P, Rodriguez G, Inguglia F, Mignone A, Guerra UP, Nobili F. The basal ganglia matching tools package for striatal uptake semi-quantification: description and validation. Eur J Nucl Med Mol Imaging. 2007 Aug;34(8):1240-53. doi: 10.1007/s00259-006-0357-2.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/striatal-dopamine-transporter-imaging-in-parkinsons-disease-drug-naive-patients-focus-on-sexual-dysfunction/