A recent study led by Johns Hopkins Medicine researchers suggests that dopamine, a neurotransmitter associated with pleasure and motivation, plays a crucial role in determining how physically demanding activities feel to individuals. The study focused on people with Parkinson’s disease, a condition characterized by the loss of dopamine-producing cells in the brain.
The researchers found that dopamine availability in the brain is a key factor in people’s perception of effort during physical tasks. Individuals with higher dopamine levels tend to perceive physical effort as easier compared to those with lower dopamine levels. The study’s findings could potentially lead to improved methods for encouraging individuals to adopt and maintain exercise routines, as well as new treatments for fatigue associated with depression and other conditions. Furthermore, it may enhance our understanding of Parkinson’s disease.
The study involved 19 adults diagnosed with Parkinson’s disease who were asked to perform a physical task—squeezing a hand grip—on two different occasions. On one occasion, they took their regular dopamine medication, while on the other, they abstained from taking the medication. The researchers found that when the participants took their medication, their self-assessment of effort expended was more accurate, and they had less variability in their efforts. In contrast, when they didn’t take the medication, they consistently over-reported their efforts and had more variability in their performance.
The study also examined the participants’ willingness to take risks involving physical effort-based decision-making. The researchers observed that when the participants took their medication, they were more willing to take a chance on tasks requiring higher effort levels compared to when they didn’t take their medication. This suggests that dopamine’s influence on risk-taking preferences specifically applies to physical effort-based decisions.
Overall, the study highlights the critical role of dopamine in accurately assessing the effort required for physical tasks, which can significantly impact individuals’ motivation and willingness to engage in future tasks. Understanding the biology and chemistry of motivation, particularly the role of dopamine, could have implications for promoting exercise and physical therapy regimens, as well as addressing fatigue in conditions such as depression, long COVID, and during cancer treatments. The researchers are further investigating dopamine’s involvement in clinical fatigue.