Objective: Aim of the study was to assess prevalence and severity of ICBs in PD patients with GBA mutations.

Background: Parkinson disease (PD) is a complex disorder for which both rare and common genetic variants contribute to the pathogenesis. Genetic forms of PD may have different phenotype compared to idiopathic patients. Mutations of the GBA gene have been recognized as the major genetic risk factor for PD. PD patients with GBA mutation may show early disease onset and higher prevalence of non-motor features. While the cognitive profile of GBA carriers has been widely described, less is known regarding their psychiatric symptoms. Impulse control behaviours (ICBs) are among the most disabling psychiatric conditions related to PD medical therapy, in particular to dopamine agonists.

Method: From the in-house PD genetic registry, 21 carriers of mutations in GBA gene, 20 in PARK2 gene and 32 patients without mutations in genes associated to PD were recruited. No patients had dementia. ICBs were diagnosed using a semi-structured interview with patient and caregiver based on current criteria for gambling, hypersexuality, compulsive shopping, compulsive eating, hobbyism/punding and compulsive medication use. The severity of ICB symptoms was assessed by the Questionnaire for impulsive-compulsive disorders in PD–rating scale (QUIP-RS). Furthermore, data on motor features, antiparkinsonian medications, executive functions and psychiatric symptoms were collected. Between-group comparisons and logistic regression analysis were carried out.

Results: The three groups were comparable for most of the characteristics, including antiparkinsonian medications and severity of motor signs. PARK2 patients showed younger age at disease onset, longer disease duration and a better performance on executive functions tests. GBA patients had higher prevalence of ICB (62%) compared to PARK2 (30%) and idiopathic (25%) patients; the QUIP-RS total score was higher in the GBA group. The logistic regression analysis showed that harboring GBA mutations as well as the dopamine agonists’ daily dose increased the odd-ratio for ICB occurrence.

Conclusion: This study enriches the clinical phenotype associated to GBA mutations, showing higher prevalence and severity of ICB symptoms. Although this finding has to be confirmed in large cohort studies, it may stand as advice in clinical management of PD patients with GBA mutations.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/impulsive-control-behaviours-in-patients-with-gba-park2-and-without-mutations-in-genes-associated-to-parkinsons-disease/