Impulse control disorders and dopamine receptor agonism in Parkinson's disease patients: Clinical implications

The association between impulse control disorders (ICDs) and dopamine agonist (DA) treatment in Parkinson's disease (PD) has been well known and extensively researched since the early 2000s. The most common behaviors included in ICDs are compulsive shopping, pathological gambling and hypersexuality which confer substantial burdens to patients and families. DAs show a more stable effect on motor control and confer lower risk of dyskinesia than levodopa, however due to the burden of ICDs, DAs in PD treatment are approached with increasing caution. Mechanisms and risk factors for ICD development in PD patients treated with DAs have been linked to D3 receptor agonism, premorbid traits and genetic predispositions. In this review we sought to examine the relevance of the degree of dopamine receptor subtype selectivity and risk of ICD, and implications for clinical practice. In line with current views, we found D3 receptor agonism to be more consistently associated with increased ICD risk compared to agents with wider receptor agonism profiles. However, this may also be explained by the difference in extended release (ER) and immediate release (IR) formulations. These findings provide the possibility that both ER formulations and agonists with wider dopamine receptor profiles may be preferred in order to reduce ICD risk in DA therapy. However, DAs confer significantly increased risk nonetheless, and as such it may be advisable to limit the use of these DAs to clinical contexts in which their administration is strongly indicated.