Human bodies naturally become slower in their movement as they age. Some potential explanations might include slow metabolism, loss of muscle mass and becoming less active over time.
Scientists believe this new research recently published in the journal The Journal of Neuroscience may help lead to new diagnostic tools for diseases such as Parkinson’s disease and multiple sclerosis. For this study, researchers recruited 84 healthy participants, including younger adults ages 18 to 35 and older adults ages 66 to 87.
During the study, participants were asked to reach for a target on a screen holding a robotic arm in their right hand. The robotic arm operated similarly to a computer mouse. Through analyzing the patterns of how study participants performed their reaches, scientists found that older adults modified their movements at certain times to help conserve their more limited amounts of energy, compared to younger adults.
Doctors say that as people age their muscle cells become less efficient in transforming energy into muscle force and movement. Humans also become less efficient in their movement strategies, possibly to compensate for lower strength. Therefore, they recruit more muscles, which costs more energy, to perform the same tasks.
Researchers in this study wanted to see how ageing might affect the reward circuitry within the brain since the body produces less dopamine as people age. Participants in this study were asked to use the robotic arm to operate a cursor on a computer screen and this objective was to reach a particular target on that screen. The objective is to reach a particular target on the screen and if they hit the target, participants were rewarded with a ‘bing sound’. Researchers found both young and older adults arrived at the targets quicker when they knew they would hear the “bing.”
However, scientists say they achieved this differently younger adults just moved their arms faster while older adults improved their reaction times, starting their reach with the robotic arm about 17 milliseconds sooner on average.
Researchers believe that their findings might help lead to a new diagnostic tool for movement-related disorders. Movement slowing as people age can significantly impact the quality of life since it can restrict not only physical but also social activities. It’s important to understand the underlying causes and determine if there are potential interventions that can help slow or eliminate the decline. Additionally, slowing of movement not only occurs with age but is a symptom of several neurological disorders.
This study on why older adults move slower offers an intriguing hypothesis linking slower movements to energy conservation and reward processing. However, the conceptual leap from observed behavior to underlying neural mechanisms requires cautious interpretation. Without direct neurological evidence correlating movement patterns with brain function changes due to ageing, the conclusions remain speculative.
