Study Goal:

Impulse control is the ability to think before we act on our urges. It allows us to withhold actions that are inappropriate and consider the consequences of a decision before modifying the decision as needed. People with Parkinson's can have impaired impulse control. In addition to this, some medications (dopamine agonists) used to help alleviate the symptoms of Parkinson's can increase the risk of developing impulse control disorders. Behaviours associated with impulse control disorders include pathological gambling, binge eating, compulsive shopping and hyper-sexuality. Currently, there is no objective (unbiased) way to identify people who are at risk of developing impulse control disorders. This project aims to identify unbiased markers of impulse control in people with Parkinson's. Identifying these markers would help to identify people with Parkinson's who are at risk of developing impulse control disorders. It would also help to develop a tool to predict, and interventions to prevent, these disorders in the future.

What's Involved:

Participants will undergo screening tests to check their eligibility. The researchers will measure muscle, an area of the brain called the motor cortex, and an area of the brain called the prefrontal cortex. The participants will then complete a simple computer task. The computer task involves the participant holding their two index fingers on sensors. On a screen, there are two bars that “fill up” towards a target level. On Go Trials, the participant needs to remove their fingers from the sensors as the bars fill to the target level. On Stop Trials, the bar will stop filling up before getting to the target level. Here, the participant must keep their fingers on the sensors. This means they must cancel their lifting response. The ability to cancel this response is an index of their impulse control. 

The computer task is completed in two separate sessions with different brain recordings being taken. One session includes Non-Invasive Brain Stimulation (TMS) and the second session includes recording electrical brain activity (EEG). Each session lasts 3 hours and takes place at the University of Birmingham. Participants will also be asked to complete a questionnaire to explore how impulse control problems manifest in real life. Travel and accommodation can be provided, and participants will be reimbursed for their time (£10/hour). 

Who Can Take Part?

• Older adults without Parkinson's (recruitment now completed)

• People with Parkinson's who haven't started on medication (de novo) 

• People with Parkinson's on dopamine agonist medication (Ropinirole)

Other criteria includes:

• 40-80 years old

• No other neurological diseases other than Parkinson's

• Normal or corrected to normal vision 

• No contraindications to brain stimulation (e.g. history of seizures, severe head trauma)