Impulse control disorders in Parkinson’s disease: a national Swedish registry study on high-risk treatments and vulnerable patient groups

Background Impulse control disorders (ICDs) are known psychiatric conditions in Parkinson’s disease (PD), especially as a side effect of antiparkinsonian therapy. Screening for vulnerable patients and avoiding high-risk treatments can be an effective approach to reduce the ICD burden in patients with PD. Thus, our goal was to identify risk factors for ICDs in PD in the Swedish total population. Methods Our longitudinal study was based on records of all patients with PD in the Swedish National Patient Registries and the Prescribed Drug Register (n=55 235). Patients with incident gambling disorder and other ICDs were compared with a control group on demographic factors, psychiatric comorbidity, antiparkinsonian dopaminergic treatment and therapies for advanced disease. Potential risk factors were analysed using logistic regressions and relative frequency comparisons (Fisher’s exact test). Results Main predictors for incident gambling disorder were treatment with dopamine agonists (Frequency ratio 1.4, p=0.058), monoamine oxidase B (MAO-B) inhibitors (Frequency ratio 1.8, p=0.006) and a prescription for drugs used in addictive disorders (OR 5.85, 95% CI 2.00 to 17.10). Main predictors for other ICDs were dopamine agonist treatment (frequency ratio 1.6, p=0.003), anxiety disorders (OR 7.04, 95% CI 2.96 to 16.71) and substance use disorders other than alcohol (OR 5.66, 95% CI 1.75 to 18.23). Conclusions Our results support possible risk factors for incident ICDs that had previously been identified, like dopamine agonist treatment and raise additional attention for risk factors like MAO-B inhibitor treatment and specific psychiatric comorbidities. These findings enable tailoring antiparkinsonian therapy to individual patient-specific risk profiles.