Impulse control and related behavioral disorders in Parkinson's disease. Risk factors, diagnosis, and management. Is there a possible role for non-invasive brain stimulation?

Parkinson's disease (PD) is a neurodegenerative disease characterized by motor and non-motor symptoms. Among the non-motor symptoms, Impulse Control Disorders (ICDs) and related behaviors (ICBs), severely affect patient's global health. Despite their psychosocial consequences, ICDs are underrecognized in PD because routine screening is still not common. The main risk factor for ICDs is the use of dopamine agonists (DAs). Therefore, the latest guidelines on ICDs management emphasize pharmacological adjustments. However, these approaches are not always feasible due to the recurrence or worsening of motor and/or non-motor symptoms. As a result, there is an urgent need to find alternative solutions for the management of PD-ICDs. Cognitive Behavioral Therapy (CBT) has shown promising results, improving not only patients' ICDs but also caregivers' well-being. Deep Brain Stimulation (DBS) seems instead effective for the motor symptoms of PD but is not indicated for ICDs. Finally, Non-Invasive Brain Stimulation (NIBS - namely, repetitive Transcranial Magnetic Stimulation and transcranial Direct Current Stimulation), has shown the potential to improve motor and cognitive symptoms in PD by targeting the supplementary motor area (SMA) and the dorsolateral prefrontal cortex. Preventative strategies considering demographic, clinical, genetic, and cognitive risk factors could help identify individuals at very high vs. low risk of developing ICDs. These strategies may assist clinicians in making informed drug choices in PD patients, prioritizing L-dopa for motor symptoms management and evaluating additional approaches such as NIBS to prevent ICDs. However high-quality studies remain lacking, and further controlled trials are necessary to validate the effectiveness of these approaches.