Parkinson’s patients work their brains harder to stay motivated

A new study from the University’s School of Medicine found that patients with Parkinson’s can create a back channel within their brain that they may use to prevent them from becoming apathetic – one of the first and most prevalent symptoms of the illness.

Using an MRI scanner to study Parkinson’s patients while completing a specially created task, the Dundee team noted increased activity in an area of the brain, effectively reprogramming it to ensure that a person maintains their levels of motivation.

This discovery, published in the prestigious journal Brain, could lead to new treatments that significantly improve the quality of life of people living with Parkinson’s disease.

“People with Parkinson’s who develop apathy have a much poorer quality of life,” said Dr Tom Gilbertson, Senior Clinical Lecturer & Honorary Consultant Neurologist at the University’s School of Medicine.

“That includes an increased likelihood of developing dementia and being less likely to respond to treatments that are normally highly effective, including surgery.

“They are less incentivised by decisions and actions that could lead to rewarding outcomes, which in the real world could see a person being less likely to seek social interaction or pursue a hobby they have enjoyed. That is because their brain does not embed information about what is valuable and loses its ability to remind a person of what is worth doing to achieve a goal.

“This is the first study to show that the brain can, even in a diseased state like it is with Parkinson’s, override the loss of this function. Understanding the mechanisms behind this compensation could help us develop new treatments aimed at treating or preventing apathy to transform the quality of life for patients.”

Apathy can often be mistaken for depression, however, while people with depression can feel pessimistic about their future, those considered apathetic feel indifferent and unmotivated.

Study participants were challenged to play a computer game where they had to obtain as many points as possible when asked to choose between four options. In a similar way to the fluctuations of the stock market, the value of the four options changed throughout the game so they had to decide whether to stay or switch their option depending upon feedback. This was conducted while the individuals were within an MRI scanner, allowing the Dundee team to study their brain activity throughout the challenge.

Those who were apathetic were able to identify the best option but tended to give up on this option prematurely, moving on to a different one despite it being potentially worse. However, those who did not display apathy were able to track the best option as well as healthy participants.

“The thalamus sits very deep within the brain and this node that we discovered connects between the thalamus and an area of the frontal lobe called the prefrontal cortex,” continued Dr Gilbertson.

“The non-apathetic Parkinson’s patients were able to activate this loop more than the healthy participants. We think this is likely to maintain their levels of motivation. The circuit we have identified could represent a biomarker which could be used to identify treatments which preserve motivation and potentially delay apathy from arising in the future.”

Dr Gilbertson and colleagues recruited 75 volunteers for their study, 53 of which had been diagnosed with Parkinson’s disease, with and without clinical apathy, and a further 22 as age-matched, healthy controls.

In analysing the results and noting the change in behaviours, Dr Gilbertson believes that apathetic tendencies could be a result of the brain’s inability to accurately represent the value of options presented to some Parkinson’s patients.

He added, “It is possible that what is happening here is that when we lose one neuromodulatory system like dopamine, which is predominantly lost in Parkinson’s, another, like serotonin or noradrenaline takes over. The potential for the brain to demonstrate capacity to get around one system being lost – like with stroke patients – needs to be proven, and that is where we will look to expand on this research. If we can prove that then we can identify new therapies.”