Implications of Impulse Control Disorder in Parkinson Disease

Parkinson disease (PD) is a progressive neurodegenerative illness that is recognized clinically by its cardinal motor features: tremor, rigidity, and bradykinesia. However, it is increasingly clear that much of the suffering and disability associated with PD is caused by psychiatric disorders. Some of these seem to be intrinsic to PD and likely emerge from the same pathogenic process that gives rise to the motor symptoms. For example, depression, anxiety disorders, and dementia are all common in PD and likely occur because the same process that damages motor circuits can also affect brain regions that subserve mood and cognition. Other psychiatric problems are associated with PD because they are caused—at least in part—by the dopaminergic medications prescribed for motor symptoms. These include delirium, psychosis, and impulse control disorders.