Ask an Expert: Dr. Caroline Paquette Discusses Fatigue in People with Parkinson’s
Dr. Caroline Paquette is a kinesiologist specializing in motor control, with a focus on balance and locomotion, and is the director of the Human Brain Control of Locomotion laboratory at McGill University. Her work integrates biomechanics, non-invasive brain stimulation, and brain imaging to better understand how our brain controls balance and locomotion. Her work also aims to advance our understanding of walking to inform clinical therapeutic alternatives to improve or maintain mobility in people with Parkinson’s disease (PD).
The research team directly involved on this project described below includes PhD student Jordan Bedime, MSc student Sara Perfetto, and key co-investigators Alexandra Potvin-Desrochers and Audrey Parent. All these individuals have a strong research interest in Parkinson’s and are instrumental to this project.
Can you tell us about your research focusing on fatigue and gait in Parkinson’s disease?
Fatigue is frequently reported in patients with PD. It is a non-motor symptom that interferes with daily mobility and can reduce quality of life. Fatigue is not a simple symptom and includes physical, cognitive, and emotional symptoms. It is thought that in individuals with PD and fatigue, the limbic system (a group of brain structures that primarily control emotions, memories, and motivations) might send signals to the basal ganglia (a group of brain structures that help regulate movement, balance, and learning) that interfere with its function.
In fact, when imaging the brain while the person is at rest, areas involved in motor function, in addition to limbic and attentional networks, are associated with fatigue in people with PD. These findings suggest that movements that require coordination, attention, and continuous adjustments, such as walking, could be more challenging for individuals with fatigue.
While we know that difficulties with walking in PD have been associated with the perception of fatigue, we wanted to determine how fatigue is associated with how we walk (not just at rest!). By better understanding the factors at play, these findings might inform interventions to minimize the impact of fatigue on mobility in PD.
For this study titled ‘Influence of fatigue in Parkinson’s disease on gait performance and locomotor control mechanism’, we recruited two groups of individuals with PD: one group who reported experiencing fatigue, and one group who did not. All participants wore an activity tracker for five days during the day to measure their physical activity level, and at night to monitor sleep.
The participants underwent two sessions of a special type of scan called 18F-FDG PET to measure brain activity related to walking. The scans were taken during two tasks for both groups: walking in a straight line and making a complex turn. Motion sensors were used to evaluate how fatigue affects gait performance during simple and complex walking. Finally, we also conducted interviews with the individuals who reported fatigue to explore the complexity of fatigue symptoms.
Our preliminary findings suggest patterns of brain activity differ between people who did and did not report fatigue. These differences were noticeable during simple straight walking but became much more similar during a complex task that involved walking and steering around cones.
In fact, during simple straight walking, people with fatigue activated more areas of the brain associated with what is called the default mode network (a set of regions that are normally active when we are at rest and not engaged in a task) compared to the complex walking task. This might suggest that during a simple task, people with fatigue increase their internal focus.
What were the findings of your study? What was the most surprising finding for you?
Data collection for this project ended in June 2024 and we are still in the process of analysis. What we are observing is that the brains of individuals with PD who have fatigue seem to activate brain regions differently than those who do not experience fatigue. This suggests that fatigue affects our mobility directly by changing the way we recruit our brain circuits for walking.
These differences in brain activity patterns seem to indicate dysfunction in key brain regions, such as the frontoparietal, limbic, and temporal, potentially involving attention and emotional processes. Indeed, increased activity in key regions of the default mode network may suggest heightened internal thought processes and/or increased attention to oneself during straight walking, as opposed to a more external and goal-oriented attention to the task being performed.
We are currently analyzing physical activity and sleep data to determine whether there are specific patterns associated with fatigue and mobility in day-to-day living.
We will also be comparing interview results from people with fatigue to their brain activity during the walking tasks, as well as their physical activity and sleep data, to better understand whether specific aspects of fatigue relate to certain brain patterns. For example, is emotional fatigue associated with specific brain activations?
What role do you think technology, like activity trackers or motion sensors, plays in advancing research on PD symptoms?
We believe they play a very important role by allowing us to quantify individuals’ experiences in their day-to-day environment. People with PD tend to behave very differently in laboratory settings compared to their usual surroundings. For example, they may experience more symptoms at home compared to the lab. With motion monitors, we are now able to better understand movement and sleep in the home setting compared to when we conduct assessments in the lab.
The other advantage is that we can also monitor individuals over longer periods, providing a much more accurate picture of their symptoms. Finally, these tools can likely help monitor disease progression in the future and help adjust interventions.
What motivated you to focus on fatigue in Parkinson’s for this study?
We were interested in better understanding how fatigue manifests and impacts movement – especially mobility – and how the brain activates movement. One novel aspect of our study is analyzing individual interviews with participants experiencing fatigue and combining their perceptions with more objective measurements obtained from quantifying walking, brain activity, and sleep.
How can studies like yours improve quality of life for people with PD?
A strong advantage of our project is that we are using what we call a mixed-method design where we, as described in the questions above, use subjective/qualitative data (ie: interviews) from individuals who experience fatigue and analyze those with more traditional objective/quantitative data (ie: physical activity and sleep data). This allows us to document recurring themes and the breadth of experiences, while exploring whether any specific symptom might be more strongly associated with observable measures of fatigue. For a symptom such as fatigue that is quite broad and complex, this is a very relevant design that brings the patient experience front and center. Of course, these interviews on their own are very rich and are helping us identify the most commonly used or most helpful coping techniques, and may help people with PD identify triggers of fatigue.
Fatigue and its underlying causes in PD are still poorly understood. Why do you think that is?
Fatigue is a complex symptom that cuts across several domains. It can be physical, emotional, or cognitive. We are getting better at defining and describing fatigue in PD. As a result, we are also better at measuring and quantifying fatigue, yet more progress is needed, and likely coming.
In your experience, what misconceptions do people have about fatigue in Parkinson’s disease?
It sometimes seemed to be challenging for our participants to differentiate between fatigue versus general tiredness. Another general misconception could also be that fatigue prevents you from doing activities and enjoying life, but all of our participants are still very active, attend social events, do sports, etc. It seems that they may need to find strategies to better live with fatigue. In some cases, we heard that fatigue is present but is not exacerbated by physical activity, suggesting that it is possible to feel the benefits of physical activity without exacerbating fatigue.
Has your research helped reveal any strategies people with PD can use to reduce fatigue while moving and walking?
We found that there is a very wide range of strategies, and individuals with fatigue should really try different ones to find those that best suit them. The most frequent strategies we heard from participants with fatigue are:
- Take breaks, as needed, to recover from fatigue episodes. Nap, sit down, etc.
- Do physical activity and stay active!
- Plan your activities ahead based on the time you feel more energized (seems to be most often in the morning)
- Break down tasks into smaller components
- Adjust your diet by eating less added sugar, more fruits, veggies, and things that are easy to digest
- Tell people around you when you experience fatigue, and accept help if needed
- Do the activities you enjoy, or enjoy the activities you do
What advice would you give to people with PD and their caregivers for managing fatigue in daily life?
We would encourage individuals to take time to recognize fatigue triggers, times with the most fatigue, how long it takes to recover, etc. through journaling. Understanding their own triggers should help people with Parkinson’s better determine which strategies to use. Consider disclosing fatigue to people who live with you as it might help them understand how you are feeling.
This content was published in the Summer 2025 edition of our quarterly magazine, Viewpoints. The content was accurate as of this publication date.