Impulse control behavior in GBA-mutated parkinsonian patients

Objective: To assess the prevalence and phenomenology of Impulse control behavior (ICB) in Parkinson's disease (PD) patients carrying mutations in the β-glucocerebrosidase (GBA) gene. Background: GBA mutations are a common genetic factor predisposing to PD. ICB is among the most disabling non-motor complications of PD. The occurrence of ICB in PD patients carrying GBA gene mutations (GBA-PD) has not been yet established. Methods: Forty-six patients with clinically definite PD (23 GBA-PD and 23 non-mutated patients, NM-PD) were screened for ICB. Diagnosis was clinically and rating based on a specific questionnaire (QUIP-RS). Other demographic and clinical variables did not differ between groups. Results: ICB occurred more frequently in GBA-PD patients (52.2%) compared to NM-PD (13%) and the total QUIP-RS score was higher in the GBA-PD group. Hypersexuality and compulsive shopping were the most prevalent ICB types occurring in GBA patients. ICB occurred only in one GBA-PD patient on levodopa monotherapy and in 11 patients taking dopamine agonists, either monotherapy or combined with levodopa (the corresponding figures in NM-PD patients were 0 and 3). Most GBA-PD patients were heterozygous for two common genetic variants, without appreciable difference in their ICB profile. Conclusion: ICB is more common in GBA-PD patients compared to NM-PD. Dopamine agonist therapy may be synergic to GBA carrier status for ICB occurrence.